Downloads & Free Reading Options - Results

In the photograph, the contour lines indicate temperature at Mach 19 around a generic vehicle similar to the X-30. Because of high pressure and skin friction, the temperature is highest on the surface of the model. The vivid blue color indicates temperature 18 times hotter than the atmosphere, requiring active cooling from within the aircraft to control temperature on the planes surface. Pink color on the outer rings is much cooler than the blue near the body, but is still 2 times hotter than the environment in which the plane travels.

In the photograph, the contour lines indicate temperature at Mach 19 around a generic vehicle similar to the X-30. Because of high pressure and skin friction, the temperature is highest on the surface of the model. The vivid blue color indicates temperature 18 times hotter than the atmosphere, requiring active cooling from within the aircraft to control temperature on the planes surface. Pink color on the outer rings is much cooler than the blue near the body, but is still 2 times hotter than the environment in which the plane travels.

With the ever growing computational power available on the largest parallel machines, the ability to generate CFD simulation data is outpacing the ability to analyze and visualize it. This is due to the large disparity between the computational facilities (up to hundreds of thousands of cores) and the typical personal computer or visualization cluster. This project's goal was to begin the analysis and visualization of these large data sets on the parallel computers they are being run on. This reduces the file size and further computation required to fully analyze the results. In this report we detail the steps that were taken in order to enable ParaView and VTK to perform this coprocessing of simulation data and visualization and analysis information. The main highlights are GUI tools to easily specify what is to be outputted during the simulation run and a coprocessing library that gets connected to the simulation code that does the actual processing of the desired results. In addition, we demonstrate good parallel performance for the coprocessing library on an IBM

Introduction Large industrial factories often discharge significant quantities of low-pressure steam (dead steam) into the atmosphere, which causes energy losses. Retaining low-pressure steam content reduces boiler load, resulting in energy savings and lower costs for the fuel consumption (for example, gas consumption bill in a factory). The boosted-pressure steam is used in processes such as distillation, hot water production, space heating or vacuum generation. If the vapor pressure for the intended application is low, a thermo-compressor is able to increase the pressure and temperature to the required level. Thermo-compressors are a special type of gas compressor that uses an actuator to compress secondary fluid and does not have any blades or moving parts. The accurate prediction of the thermo-compressor performance improves the reliability of this process and increases its efficiency. Materials and Methods Two important characteristics for the current thermo-compressors are entrainment ratio (ER) and compression ratio (CR). The first is the dimensionless mass flow rate, and the second is the dimensionless pressure. The wet steam theory as a classic theory is used by Wolmer-Frankel-Zeldovich to calculate the amount of liquid particles. In order to select the best geometry for the thermo-compressor among all possible geometries, the performance of each model must be compared with other models. In following, the case that includes characteristic parameters associated with the target values has been selected. The commercial Ansys Fluent Versions 15, based on the finite volume method (FVM) was used to simulate and monitoring the flow behavior inside the thermo-compressor. The governing partial differential equations (PDE) were solved implicitly using a density-based solution. The convective heat transfer terms were discriminated based on the second-order upwind scheme. The non-linear governing equations were solved using the implicit coupling solver and the standard wall function was used near the wall. Given the three-dimensional flow for steam, the equations of mass conservation, momentum, and energy were written. The Realizable  model was used to simulate turbulences in the flow. Results and Discussion A summary of the results is presented in terms of the results of pressure, velocity magnitude, Mach number and temperature. A general understanding of this characteristic for a thermo-compressor is extremely important for recognizing the fluid flow inside it, and it is very useful for practical use. Pressure is the most important factor in the recharge section of a thermo-compressor. Increasing the recharge vapor pressure in a thermos-compressor revival the dead steam and increases the steam efficiency. The revival steam can be used in other parts because of their high thermal content. Another important factor in the study of flow behavior inside the thermocouple is velocity magnitude. This quantity, which is closely related to the concept of momentum inside the thermocouple, had high influences from high pressure inputs as well as the thermo-compressor geometry. The highest amount of velocity occurs after the initial nozzle and had a very high magnitude (1000 ms -1 ), which was also remarkably high in Monnet's terms. Another important characteristic of a flow is the temperature of the stream. The high input temperature associated with motive vapor at the outlet of the primary nozzle was sharply reduced, even in some section reached to 110 °Kelvin. Due to the very high flow momentum in this section, the fluid phase remained gas and it can be justified from the point of view of the fluid dynamics. Conclusion Considering the importance of thermodynamic properties of steam in conversion and industries, it would be extremely beneficial to fully understand the interactions inside the thermocouple compressor. The importance of the discussed characteristics is more specific when there is a close relationship between each of these factors and energy consumption in a factory or in any industrial production unit. It was observed that the designed thermos-compressor was able to increase the velocity and temperature in a desirable range for the conversion of non-consumable vapor to the pressure and temperature. It was concluded that the Realizable  model due to the prediction of the jet characteristics appearing in the flow regimes for axial symmetry had a high ability to simulate fluid flows inside the thermos-compressor.

Recent advances in achieving textbook multigrid efficiency for fluid simulations are presented. Textbook multigrid efficiency is defined as attaining the solution to the governing system of equations in a computational work which is a small multiple of the operation counts associated with discretizing the system. Strategies are reviewed to attain this efficiency by exploiting the factorizability properties inherent to a range of fluid simulations, including the compressible Navier-Stokes equations. factorizability is used to separate the elliptic and hyperbolic factors contributing to the target system; each of the factors can then be treated individually and optimally. Boundary regions and discontinuities are addressed with separate (local) treatments. New formulations and recent calculations demonstrating the attainment of textbook efficiency for aerodynamic simulations are shown.

The TLNS3DR code is applied to various advanced rotor blades to study tip vortex and to investigate the general capabilities of the code. For nonrotating flows, the solutions in terms of the tip vortex and surface pressure coefficients are obtained for realistic helicopter rotor-tip configurations to study effects of blade planforms on the tip vortex under incompressible flow condition. Calculated results are compared with experimentally obtained data at NASA-Langley's Basic Aerodynamic Research Wind Tunnel (BART). A Berp-type tip, a swept-type tip and its equivalent taper-type tip configurations are investigated. For both nonrotating and rotating flows, the Berp-type blade, the swept-type blade, and its equivalent taper-type and rectangle-type blades with zero twist are considered under compressible flow condition. Solutions are presented. (AN)

This report consists of brief technical descriptions and one or more pictures of charts depicting research conducted in-house during the past year. The briefs are designed to provide enough information to clearly define the task, but are short enough to hold the reader's interest. Where applicable, a reference for more detailed information is provided. The research covers a wide spectrum of work; from grid generation to flow solvers, to post-processors; and from incompressible to hypersonic speeds.

The effort has had several components since it was initiated in Oct of 1989; all of these had as their objective the assistance of Dr. Joseph Shang at WRDC in the redirection of his effort toward use of massively-parallel architectures. The major objective was to gain algorithm experience in conversion of two Air Force production CFD codes to a general format applicable to a variety of commercial message-passing architectures. Earlier, an explicit N-S 3D code from WRDC had been converted to the NCUBE. This was used as a model for parallelized production code developed at WRDC under DARPA sponsorship. This effort was completed with the conversion of a serial full 3D Navier-Stokes Beam- Warming CFD code to a 1024-node scalar NCUBE hypercube at SANDIA (Albuquerque).

The Air Force SEEK EAGLE Office (AFSEO), Eglin Air Force Base (AFB), FL, is the United States Air Force (USAF) authority for weapons certification efforts. AFSEO performs test and evaluation for aircraft/store compatibility certification and uses Computational Fluid Dynamics (CFD) to support this process. Determining the flow about an aircraft/store combination can be extremely difficult. Complicated geometry such as pylons, launchers, and internal weapons bays can create severe acoustic and aerothermodynamic environments, which are challenging to numerically simulate. The additional challenge of rapidly and accurately simulating the trajectory of a store separation in a high-volume simulation environment is beyond the capabilities of most CFD programs. The USAF requirement for numerous, simultaneous and quick-reaction solutions for a wide variety of stores and aircraft can only be accomplished through application of parallel high-performance computing resources that meet the significant computational and memory demands of the various cases.

In the spirit of the Air Force Office of Scientific Research's (AFOSR) initiative to promote University-Industry Collaborative Research, a collaborative project entitled, Hybrid Techniques in Computational Fluid Dynamics (CFD) has been executed by the National Science Foundation Engineering Research Center for Computational Field Simulation (NSF ERC) at Mississippi State University. The industrial participants include McDonnell Douglas Company, Boeing Company, and Teledyne Brown Engineering Company. The research and development activities of this effort are focused on the advancement of methodologies to increase the efficiency, quality, and productivity of an overall CFD simulation associated with geometrically complex configurations. The progress realized in the aforementioned development is presented in this final report. Progress concerning efforts designed to improve the efficiency and applicability of the CFD to geometrically complex configurations utilizing hybrid techniques is presented. This progress has been brought about through the developments and enhancements in hybrid grid generation methodology and solution algorithms for associated Euler and Navier-Stokes equations. In particular, the enhancement of the two and three dimensional hybrid grid system and CFD simulation solver is presented. The development of the three dimensional hybrid grid system and solution system allowing viscous effects with complex examples is presented to demonstrate the success of these methodologies.

The first and largest color Sun 3/160C in the CFD workstation network was purchased with funds made available through this grant. This workstation has been used as a server and general computational node, as well as a workstation. Research Projects: Development of Adaptive Grid Schemes based on Poisson Grid Generators; A Zonal Method for Extending the Applicability of the Parabolized Navier Stokes Equations; and Numerical Simulation of Helicopter Rotor Flowfields.

The divide-and-conquer paradigm of iterative domain decomposition, or substructuring, has become a practical tool in computational fluid dynamics applications because of its flexibility in accommodating adaptive refinement through locally uniform (or quasi-uniform) grids, its ability to exploit multiple discretizations of the operator equations, and the modular pathway it provides towards parallelism. We illustrate these features on the classic model problem of flow over a backstep using Newton's method as the nonlinear iteration. Multiple discretizations (second-order in the operator and first- order in the preconditioner) and locally uniform mesh refinement pay dividends separately, and they can be combined synergistically. We include sample performance results from an Intel iPSC/860 hypercube implementation.

We developed a novel approach to extend the particle level set method to the simulation of as many regions as desired. The various regions can be liquids or gases of any type with differing viscosities, densities, viscoelastic properties, etc. We also proposed techniques for simulating interactions between materials, whether it be simple surface tension forces or more complex chemical reactions with one material converting to another or two materials combining to form a third. When discretizing the underlying Navier-Stokes equations for multiphase flow, an additional difficulty occurs since discretization stencils cross region boundaries naively combining non-smooth or even discontinuous data. Recently, we developed a new coding paradigm that allows one to incorporate physical jump conditions in data on the fly, which is significantly more efficient for multiple regions, especially at triple points or near boundaries with solids. This removes the need for any algorithm changes that might reduce the accuracy of the scheme, and moreover even removes the need for changes to the code itself. Besides this work we have also addressed scalability including methods on octree and Run Length Encoded (RLE) data structure, as well parallel implementation such as MPI. Other work includes work on fracture.

The Unsteady Reynolds-Averaged Navier Stokes (URANS) approach applied in conjunction with the Eddy Interaction Model (EIM) is used here to conduct numerical simulations of aerosol particle deposition on the human form. Numerical simulation of a two-phase turbulent impinging jet flow is studied to validate the proposed methodology. The numerical deposition results are compared with some relevant experimental measurements. The results of this validation show that the standard EIM with turbulent tracking tends to over predict the deposition efficiency. Greatly improved results were achieved by using a near-wall correction with the EIM. After the validation of the methodology, a number of detailed numerical simulations of aerosol particle deposition on a human form were conducted. Simulations were conducted for 13 aerosol particle sizes ranging from 0.1 to 40 micrometers. For each of these particle sizes, three orientations of the human form relative to the incident wind direction were simulated (viz., with the human form oriented 0, 90 and 180 degrees with respect to the direction of the incident wind). High-resolution isopleths of the deposition probability on the surface of the human form are presented. To provide the quantitative information for future applications by researchers, extensive data files have been produced, providing information on the cell area for each triangle used in the tessellation of the surface of the human form, the associated body part associated with this triangular cell, and the computed deposition probability associated the triangular cell.

A systematic approach is presented for developing entropy stable (SS) formulations of any order for the Navier-Stokes equations. These SS formulations discretely conserve mass, momentum, energy and satisfy a mathematical entropy inequality. They are valid for smooth as well as discontinuous flows provided sufficient dissipation is added at shocks and discontinuities. Entropy stable formulations exist for all diagonal norm, summation-by-parts (SBP) operators, including all centered finite-difference operators, Legendre collocation finite-element operators, and certain finite-volume operators. Examples are presented using various entropy stable formulations that demonstrate the current state-of-the-art of these schemes.

Computational Fluid Dynamics Principles And Applications J. Blazek

Experimental techniques to measure rotorcraft aerodynamic performance are widely used. However, most of them are either unable to capture interference effects from bodies, or require an extremely large computational budget. The objective of the present research is to develop an XV-15 Tilt Rotor Research Aircraft rotor model for investigation of wind tunnel wall interference using a novel Computational Fluid Dynamics (CFD) solver for rotorcraft, RotCFD. In RotCFD, a mid-fidelity URANS solver is used with an incompressible flow model and a realizable k-e turbulence model. The rotor is, however, not modeled using a computationally expensive, unsteady viscous body-fitted grid, but is instead modeled using a blade element model with a momentum source approach. Various flight modes of the XV-15 isolated rotor, including hover, tilt and airplane mode, have been simulated and correlated to existing experimental and theoretical data. The rotor model is subsequently used for wind tunnel wall interference simulations in the National Full-Scale Aerodynamics Complex (NFAC) at NASA Ames Research Center in California. The results from the validation of the isolated rotor performance showed good correlation with experimental and theoretical data. The results were on par with known theoretical analyses. In RotCFD the setup, grid generation and running of cases is faster than many CFD codes, which makes it a useful engineering tool. Performance predictions need not be as accurate as high-fidelity CFD codes, as long as wall effects can be properly simulated. For both test sections of the NFAC wall interference was examined by simulating the XV-15 rotor in the test section of the wind tunnel and with an identical grid but extended boundaries in free field. Both cases were also examined with an isolated rotor or with the rotor mounted on the modeled geometry of the Tiltrotor Test Rig (TTR). A 'quasi linear trim' was used to trim the thrust for the rotor to compare the power as a unique variable. Power differences between free field and wind tunnel cases were found from -7 % to 0 % in the 80- by 120-Foot Wind Tunnel test section and -1.6 % to 4.8 % in the 40- by 80-Foot Wind Tunnel, depending on the TTR orientation, tunnel velocity and blade setting. The TTR will be used in 2016 to test the Bell 609 rotor in a similar fashion to the research in this report.

The research has focussed on a class of domain decomposition techniques for solution of problems in Computational Fluid Dynamics using advanced vector and parallel processors. In particular we consider finite element schemes and use the natural element schemes and use the natural element- partition of the domain to construct the decomposition algorithm. This then fits conveniently into the usual framework of finite element calculations in which the primary loop is the independent calculation and assembly of element matrix and vector contributions. By recasting the conjugate gradient method at this level, the system matrix need not be assembled and the intensive matrix-vector product step can be completely parallelized. These ideas constitute a major departure from traditional finite element schemes and we feel our efforts are a major new development that will strongly influence the technology. Parallel processing, Domain decomposition.

Some recent developments in acceleration of convergence methods for vector sequences are reviewed. The methods considered are the minimal polynomial extrapolation, the reduced rank extrapolation, and the modified minimal polynomial extrapolation. The vector sequences to be accelerated are those that are obtained from the iterative solution of linear or nonlinear systems of equations. The convergence and stability properties of these methods as well as different ways of numerical implementation are discussed in detail. Based on the convergence and stability results, strategies that are useful in practical applications are suggested. Two applications to computational fluid mechanics involving the three dimensional Euler equations for ducted and external flows are considered. The numerical results demonstrate the usefulness of the methods in accelerating the convergence of the time marching techniques in the solution of steady state problems.

The aerospace plane design challenge is presented in the form of the view-graphs. The following topics are included: the CFD design technology development; CFD validation vs. measurable fluid dynamics validation; and discussion of results.

A system of computer programs was developed to model general three dimensional surfaces. Surfaces are modeled as sets of parametric bicubic patches. There are also capabilities to transform coordinates, to compute mesh/surface intersection normals, and to format input data for a transonic potential flow analysis. A graphical display of surface models and intersection normals is available. There are additional capabilities to regulate point spacing on input curves and to compute surface/surface intersection curves. Input and output data formats are described; detailed suggestions are given for user input. Instructions for execution are given, and examples are shown.

Design and analysis of the inlet for a rocket based combined cycle engine is discussed. Computational fluid dynamics was used in both the design and subsequent analysis. Reynolds averaged Navier-Stokes simulations were performed using both perfect gas and real gas assumptions. An inlet design that operates over the required Mach number range from 0 to 12 was produced. Performance data for cycle analysis was post processed using a stream thrust averaging technique. A detailed performance database for cycle analysis is presented. The effect ot vehicle forebody compression on air capture is also examined.

This paper describes an experiment in which a large-scale scientific application development for tightly-coupled parallel machines is adapted to the distributed execution environment of the Information Power Grid (IPG). A brief overview of the IPG and a description of the computational fluid dynamics (CFD) algorithm are given. The Globus metacomputing toolkit is used as the enabling device for the geographically-distributed computation. Modifications related to latency hiding and Load balancing were required for an efficient implementation of the CFD application in the IPG environment. Performance results on a pair of SGI Origin 2000 machines indicate that real scientific applications can be effectively implemented on the IPG; however, a significant amount of continued effort is required to make such an environment useful and accessible to scientists and engineers.

This paper describes and discusses the textbook, Fundamentals of Computational Fluid Dynamics by Lomax, Pulliam, and Zingg, which is intended for a graduate level first course in computational fluid dynamics. This textbook emphasizes fundamental concepts in developing, analyzing, and understanding numerical methods for the partial differential equations governing the physics of fluid flow. Its underlying philosophy is that the theory of linear algebra and the attendant eigenanalysis of linear systems provides a mathematical framework to describe and unify most numerical methods in common use in the field of fluid dynamics. Two linear model equations, the linear convection and diffusion equations, are used to illustrate concepts throughout. Emphasis is on the semi-discrete approach, in which the governing partial differential equations (PDE's) are reduced to systems of ordinary differential equations (ODE's) through a discretization of the spatial derivatives. The ordinary differential equations are then reduced to ordinary difference equations (O(Delta)E's) using a time-marching method. This methodology, using the progression from PDE through ODE's to O(Delta)E's, together with the use of the eigensystems of tridiagonal matrices and the theory of O(Delta)E's, gives the book its distinctiveness and provides a sound basis for a deep understanding of fundamental concepts in computational fluid dynamics.

In this paper we describe the parallelization of the multi-zone code versions of the NAS Parallel Benchmarks employing multi-level OpenMP parallelism. For our study we use the NanosCompiler, which supports nesting of OpenMP directives and provides clauses to control the grouping of threads, load balancing, and synchronization. We report the benchmark results, compare the timings with those of different hybrid parallelization paradigms and discuss OpenMP implementation issues which effect the performance of multi-level parallel applications.

The Design Analysis Branch (NE-Ml) at the Kennedy Space Center has not had the ability to accurately couple Rigid Body Dynamics (RBD) and Computational Fluid Dynamics (CFD). OVERFLOW-D is a flow solver that has been developed by NASA to have the capability to analyze and simulate dynamic motions with up to six Degrees of Freedom (6-DOF). Two simulations were prepared over the course of the internship to demonstrate 6DOF motion of rigid bodies under aerodynamic loading. The geometries in the simulations were based on a conceptual Space Launch System (SLS). The first simulation that was prepared and computed was the motion of a Solid Rocket Booster (SRB) as it separates from its core stage. To reduce computational time during the development of the simulation, only half of the physical domain with respect to the symmetry plane was simulated. Then a full solution was prepared and computed. The second simulation was a model of the SLS as it departs from a launch pad under a 20 knot crosswind. This simulation was reduced to Two Dimensions (2D) to reduce both preparation and computation time. By allowing 2-DOF for translations and 1-DOF for rotation, the simulation predicted unrealistic rotation. The simulation was then constrained to only allow translations.

Spacecraft thermal protection systems are at risk of being damaged due to airflow produced from

The current compute environment that most researchers are using for the calculation of 3D unsteady Computational Fluid Dynamic (CFD) results is a super-computer class machine. The Massively Parallel Processors (MPP's) such as the 160 node IBM SP2 at NAS and clusters of workstations acting as a single MPP (like NAS's SGI Power-Challenge array and the J90 cluster) provide the required computation bandwidth for CFD calculations of transient problems. If we follow the traditional computational analysis steps for CFD (and we wish to construct an interactive visualizer) we need to be aware of the following: (1) Disk space requirements. A single snap-shot must contain at least the values (primitive variables) stored at the appropriate locations within the mesh. For most simple 3D Euler solvers that means 5 floating point words. Navier-Stokes solutions with turbulence models may contain 7 state-variables. (2) Disk speed vs. Computational speeds. The time required to read the complete solution of a saved time frame from disk is now longer than the compute time for a set number of iterations from an explicit solver. Depending, on the hardware and solver an iteration of an implicit code may also take less time than reading the solution from disk. If one examines the performance improvements in the last decade or two, it is easy to see that depending on disk performance (vs. CPU improvement) may not be the best method for enhancing interactivity. (3) Cluster and Parallel Machine I/O problems. Disk access time is much worse within current parallel machines and cluster of workstations that are acting in concert to solve a single problem. In this case we are not trying to read the volume of data, but are running the solver and the solver outputs the solution. These traditional network interfaces must be used for the file system. (4) Numerics of particle traces. Most visualization tools can work upon a single snap shot of the data but some visualization tools for transient problems require dealing with time.

-computational fluid dynamics; a computational fluid dynamics model of flow and settling in sedimentation tanks; advances in computational fluid dynamics applied to the greenhouse environment; fluid dynamics analysis of a space vehicle entering the mars atmosphere; air movement within enclosed road-objects with contra-traffica cdf-investigation; computational fluid dynamics and discrete element method applied to centrifuges; cfd and thermography techniques applied in cooling systems designs; computational fluid dynamics modelling of photochemical reactors; aerodynamic design of the vertical takeoff hopper concept of future launchers preparatory program; fluid-structure interaction of a radial turbine; industrial sprays-experimental characterization and numerical modeling; multidimensional design of hydraulic components and systems; study of an individual air-conditioning energy-saving equipment; unsteady differentiation of aerodynamic coefficients-methodology and applications; use of fluid dynamic simulation to improve the design of spouted beds-

Computational fluid dynamics (CFD) simulations were performed in the present study using ANSYS Fluent 18.0, a commercially available CFD package, to characterize the behaviour of the new HAWT. Static threedimensional CFD simulations were conducted. The static torque characteristics of the turbine and the simplicity of design highlight its suitability for the GE 1.5xle turbine. The major factor for generating the power through the HAWT is the velocity of air and the position of the blade angle in the HAWT blade assembly. The paper presents the effect of The blade is 43.2 m length and starts with a cylindrical shape at the root then transitions to the airfoils S818, S825 and S826 for the root, body and tip respectively. This blade also has pitch to vary as a function of radius, giving it a twist and the pitch angle at the blade tip is 4 degrees. This blade was created to be similar in size to a GE 1.5xle turbine by Cornell University. In addition, note that to represent the blade being connected to a hub, the blade root is offset from the axis of rotation by 1 meter. The hub is not included in our model. The experimental analysis of GE 1.5xle turbine, so that possible the result of CFD analysis can be compared with theoretical calculations. CFD workbench of ANSYS is used to carry out the virtue simulation and testing. The software generated test results are validated through the experimental readings. Through this obtainable result will be in the means of maximum constant power generation from HAWT.

Computational fluid dynamics (CFD) simulations were performed in the present study using ANSYS Fluent 18.0, a commercially available CFD package, to characterize the behaviour of the new HAWT. Static threedimensional CFD simulations were conducted. The static torque characteristics of the turbine and the simplicity of design highlight its suitability for the GE 1.5xle turbine. The major factor for generating the power through the HAWT is the velocity of air and the position of the blade angle in the HAWT blade assembly. The paper presents the effect of The blade is 43.2 m length and starts with a cylindrical shape at the root then transitions to the airfoils S818, S825 and S826 for the root, body and tip respectively. This blade also has pitch to vary as a function of radius, giving it a twist and the pitch angle at the blade tip is 4 degrees. This blade was created to be similar in size to a GE 1.5xle turbine by Cornell University. In addition, note that to represent the blade being connected to a hub, the blade root is offset from the axis of rotation by 1 meter. The hub is not included in our model. The experimental analysis of GE 1.5xle turbine, so that possible the result of CFD analysis can be compared with theoretical calculations. CFD workbench of ANSYS is used to carry out the virtue simulation and testing. The software generated test results are validated through the experimental readings. Through this obtainable result will be in the means of maximum constant power generation from HAWT.

An axisymmetric single engine Computational Fluid Dynamics calculation of the Saturn V/S 1-C vehicle base region and F1 engine plume is described. There were two objectives of this work, the first was to calculate an axisymmetric approximation of the nozzle, plume and base region flow fields of S1-C/F1, relate/scale this to flight data and apply this scaling factor to a NLS/STME axisymmetric calculations from a parallel effort. The second was to assess the differences in F1 and STME plume shear layer development and concentration of combustible gases. This second piece of information was to be input/supporting data for assumptions made in NLS2 base temperature scaling methodology from which the vehicle base thermal environments were being generated. The F1 calculations started at the main combustion chamber faceplate and incorporated the turbine exhaust dump/nozzle film coolant. The plume and base region calculations were made for ten thousand feet and 57 thousand feet altitude at vehicle flight velocity and in stagnant freestream. FDNS was implemented with a 14 species, 28 reaction finite rate chemistry model plus a soot burning model for the RP-1/LOX chemistry. Nozzle and plume flow fields are shown, the plume shear layer constituents are compared to a STME plume. Conclusions are made about the validity and status of the analysis and NLS2 vehicle base thermal environment definition methodology.

The Australian Challenge was a set of experiments chosen as a test case to establish how well computer calculations can model the blast overpressure around a complex set of structures. This paper presents the first three dImensional calculation on the Australian Challenge using CFD codes. These codes have been developed at AMRL and the Australian Challenge represents their first test in a real world' scenario. The calculations show good agreement with the experimental results. The program can now be used with a good degree of confidence in modelling other complex scenarios, reducing the need for expensive experimentation. The safety aspects of any changes in operational procedure can be evaluated quickly and efficiently. (AN)

NASA/Marshall Space Flight Center (MSFC) has an ongoing effort to transfer to industry the technologies developed at MSFC for rocket propulsion systems. The Technology Utilization (TU) Office at MSFC promotes these efforts and accepts requests for assistance from industry. One such solicitation involves a request from North American Marine Jet, Inc. (NAMJ) for assistance in the design of a water-jet-drive system to fill a gap in NAMJ's product line. NAMJ provided MSFC with a baseline axial flow impeller design as well as the relevant working parameters (rpm, flow rate, etc.). This baseline design was analyzed using CFD, and significant deficiencies identified. Four additional analyses were performed involving MSFC changes to the geometric and operational parameters of the baseline case. Subsequently, the impeller was redesigned by NAMJ and analyzed by MSFC. This new configuration performs significantly better than the baseline design. Similar cooperative activities are planned for the design of the jet-drive inlet.

A system and method for generating fluid flow parameter data for use in aerodynamic heating analysis. Computational fluid dynamics data is generated for a number of points in an area on a surface to be analyzed. Sub-areas corresponding to areas of the surface for which an aerodynamic heating analysis is to be performed are identified. A computer system automatically determines a sub-set of the number of points corresponding to each of the number of sub-areas and determines a value for each of the number of sub-areas using the data for the sub-set of points corresponding to each of the number of sub-areas. The value is determined as an average of the data for the sub-set of points corresponding to each of the number of sub-areas. The resulting parameter values then may be used to perform an aerodynamic heating analysis.

A system and method for generating fluid flow parameter data for use in aerodynamic heating analysis. Computational fluid dynamics data is generated for a number of points in an area on a surface to be analyzed. Sub-areas corresponding to areas of the surface for which an aerodynamic heating analysis is to be performed are identified. A computer system automatically determines a sub-set of the number of points corresponding to each of the number of sub-areas and determines a value for each of the number of sub-areas using the data for the sub-set of points corresponding to each of the number of sub-areas. The value is determined as an average of the data for the sub-set of points corresponding to each of the number of sub-areas. The resulting parameter values then may be used to perform an aerodynamic heating analysis.

A transport equation for the intermittency factor is employed to predict the transitional flows in low-pressure turbines. The intermittent behavior of the transitional flows is taken into account and incorporated into computations by modifying the eddy viscosity, mu(sub p) with the intermittency factor, gamma. Turbulent quantities are predicted using Menter's two-equation turbulence model (SST). The intermittency factor is obtained from a transport equation model which can produce both the experimentally observed streamwise variation of intermittency and a realistic profile in the cross stream direction. The model had been previously validated against low-pressure turbine experiments with success. In this paper, the model is applied to predictions of three sets of recent low-pressure turbine experiments on the Pack B blade to further validate its predicting capabilities under various flow conditions. Comparisons of computational results with experimental data are provided. Overall, good agreement between the experimental data and computational results is obtained. The new model has been shown to have the capability of accurately predicting transitional flows under a wide range of low-pressure turbine conditions.

Design of Experiments (DOE) techniques were applied to the Launch Abort System (LAS) of the NASA Crew Exploration Vehicle (CEV) parametric geometry Computational Fluid Dynamics (CFD) study to efficiently identify and rank the primary contributors to the integrated drag over the vehicles ascent trajectory. Typical approaches to these types of activities involve developing all possible combinations of geometries changing one variable at a time, analyzing them with CFD, and predicting the main effects on an aerodynamic parameter, which in this application is integrated drag. The original plan for the LAS study team was to generate and analyze more than1000 geometry configurations to study 7 geometric parameters. By utilizing DOE techniques the number of geometries was strategically reduced to 84. In addition, critical information on interaction effects among the geometric factors were identified that would not have been possible with the traditional technique. Therefore, the study was performed in less time and provided more information on the geometric main effects and interactions impacting drag generated by the LAS. This paper discusses the methods utilized to develop the experimental design, execution, and data analysis.

A computational method for the analysis of longitudinal-mode liquid rocket combustion instability has been developed based on the unsteady, quasi-one-dimensional Euler equations where the combustion process source terms were introduced through the incorporation of a two-zone, linearized representation: (1) A two-parameter collapsed combustion zone at the injector face, and (2) a two-parameter distributed combustion zone based on a Lagrangian treatment of the propellant spray. The unsteady Euler equations in inhomogeneous form retain full hyperbolicity and are integrated implicitly in time using second-order, high-resolution, characteristic-based, flux-differencing spatial discretization with Roe-averaging of the Jacobian matrix. This method was initially validated against an analytical solution for nonreacting, isentropic duct acoustics with specified admittances at the inflow and outflow boundaries. For small amplitude perturbations, numerical predictions for the amplification coefficient and oscillation period were found to compare favorably with predictions from linearized small-disturbance theory as long as the grid exceeded a critical density (100 nodes/wavelength). The numerical methodology was then exercised on a generic combustor configuration using both collapsed and distributed combustion zone models with a short nozzle admittance approximation for the outflow boundary. In these cases, the response parameters were varied to determine stability limits defining resonant coupling onset.

For long-duration in-space storage of cryogenic propellants, an axial jet mixer is one concept for controlling tank pressure and reducing thermal stratification. Extensive ground-test data from the 1960s to the present exist for tank diameters of 10 ft or less. The design of axial jet mixers for tanks on the order of 30 ft diameter, such as those planned for the Ares V Earth Departure Stage (EDS) LH2 tank, will require scaling of available experimental data from much smaller tanks, as well designing for microgravity effects. This study will assess the ability for Computational Fluid Dynamics (CFD) to handle a change of scale of this magnitude by performing simulations of existing ground-based axial jet mixing experiments at two tank sizes differing by a factor of ten. Simulations of several axial jet configurations for an Ares V scale EDS LH2 tank during low Earth orbit (LEO) coast are evaluated and selected results are also presented. Data from jet mixing experiments performed in the 1960s by General Dynamics with water at two tank sizes (1 and 10 ft diameter) are used to evaluate CFD accuracy. Jet nozzle diameters ranged from 0.032 to 0.25 in. for the 1 ft diameter tank experiments and from 0.625 to 0.875 in. for the 10 ft diameter tank experiments. Thermally stratified layers were created in both tanks prior to turning on the jet mixer. Jet mixer efficiency was determined by monitoring the temperatures on thermocouple rakes in the tanks to time when the stratified layer was mixed out. Dye was frequently injected into the stratified tank and its penetration recorded. There were no velocities or turbulence quantities available in the experimental data. A commercially available, time accurate, multi-dimensional CFD code with free surface tracking (FLOW-3D from Flow Science, Inc.) is used for the simulations presented. Comparisons are made between computed temperatures at various axial locations in the tank at different times and those observed experimentally. The affect of various modeling parameters on the agreement obtained are assessed.

Launch vehicles frequently experience a reduced stability margin through the transonic Mach number range. This reduced stability margin can be caused by the aerodynamic undamping one of the lower-frequency flexible or rigid body modes. Analysis of the behavior of a flexible vehicle is routinely performed with quasi-steady aerodynamic line loads derived from steady rigid aerodynamics. However, a quasi-steady aeroelastic stability analysis can be unconservative at the critical Mach numbers, where experiment or unsteady computational aeroelastic analysis show a reduced or even negative aerodynamic damping.Amethod of enhancing the quasi-steady aeroelastic stability analysis of a launch vehicle with unsteady aerodynamics is developed that uses unsteady computational fluid dynamics to compute the response of selected lower-frequency modes. The response is contained in a time history of the vehicle line loads. A proper orthogonal decomposition of the unsteady aerodynamic line-load response is used to reduce the scale of data volume and system identification is used to derive the aerodynamic stiffness, damping, and mass matrices. The results are compared with the damping and frequency computed from unsteady computational aeroelasticity and from a quasi-steady analysis. The results show that incorporating unsteady aerodynamics in this way brings the enhanced quasi-steady aeroelastic stability analysis into close agreement with the unsteady computational aeroelastic results.

A workshop on the computational fluid dynamics (CFD) prediction of shock boundary-layer interactions (SBLIs) was held at the 48th AIAA Aerospace Sciences Meeting. As part of the workshop numerous CFD analysts submitted solutions to four experimentally measured SBLIs. This paper describes the assessment of the CFD predictions. The assessment includes an uncertainty analysis of the experimental data, the definition of an error metric and the application of that metric to the CFD solutions. The CFD solutions provided very similar levels of error and in general it was difficult to discern clear trends in the data. For the Reynolds Averaged Navier-Stokes methods the choice of turbulence model appeared to be the largest factor in solution accuracy. Large-eddy simulation methods produced error levels similar to RANS methods but provided superior predictions of normal stresses.

This paper describes the NASA ARC program in sonic boom prediction methodologies. This activity supports NASA's High Speed Research Program (HSRP). An overview of the program, recent results, conclusions, and current effort will be given. This effort complements research in sonic boom acceptability and validation being conducted at LaRC and ARC. The goals of the sonic boom element are as follows: to establish a predictive capability for sonic booms generated by High-Speed Civil Transport (HSCT) concepts; to establish guidelines of acceptability for supersonic overland flight; and to validate these findings with wind tunnel and flight tests. The cumulative result of these efforts will be an assessment of economic viability for supersonic transportation. This determination will ultimately be made by the aerospace industry.

A computational study was conducted on the use of aft-mounted fairings for passive drag reduction on a sphere at Re=866,000. The sphere dimensions and operating Reynolds number were selected to approximate the flow around a proposed aircraft laser turret for which experimental data was available. To establish the validity of the computational model, flow predictions were compared to sphere data available in the open literature. The model, exercised in both the laminar and turbulent modes, showed good agreement with the published data. Two proposed laser turret fairings were then evaluated computationally: a large fairing (beginning at 49.5 degrees past the sphere apex) and a small fairing (beginning at 58.95 degrees past the sphere apex). Existing wind tunnel models were used to generate axisymmetric computational grids that approximated the geometry of these models. The computed flow field and associated drag reduction were comparable to the experimental results obtained from the wind tunnel testing. Differences in drag from the model to the experiment were explained by the axisymmetric simplifications made in the model. Finally, a new, optimized fairing model was designed which eliminated the separation zone on the aft portion of the sphere. The optimized model predicted double the drag reduction compared to the large fairing computational model.

Ames Research Center has the lead role among NASA centers to conduct research in computational fluid dynamics. The past, the present, and the future prospects in this field are reviewed. Past accomplishments include pioneering computer simulations of fluid dynamics problems that have made computers valuable in complementing wind tunnels for aerodynamic research. The present facilities include the most powerful computers built in the United States. Three examples of viscous flow simulations are presented: an afterbody with an exhaust plume, a blunt fin mounted on a flat plate, and the Space Shuttle. The future prospects include implementation of the Numerical Aerodynamic Simulation Processing System that will provide the capability for solving the viscous flow field around an aircraft in a matter of minutes.

The ability to accurately and efficiently calculate the flow structure in the base region of bodies of revolution in supersonic flight is a significant step in CFD code validation for applications ranging from base heating for rockets to drag for protectives. The FDNS code is used to compute such a flow and the results are compared to benchmark quality experimental data. Flowfield calculations are presented for a cylindrical afterbody at M = 2.46 and angle of attack a = O. Grid independent solutions are compared to mean velocity profiles in the separated wake area and downstream of the reattachment point. Additionally, quantities such as turbulent kinetic energy and shear layer growth rates are compared to the data. Finally, the computed base pressures are compared to the measured values. An effort is made to elucidate the role of turbulence models in the flowfield predictions. The level of turbulent eddy viscosity, and its origin, are used to contrast the various turbulence models and compare the results to the experimental data.

Integration issues involved with installing the alternate turbopump (ATP) High Pressure Oxygen Turbopump (HPOTP) into the SSME have raised questions regarding the flow in the HPOTP turnaround duct (TAD). Steady-state Navier-Stokes CFD analyses have been performed by NASA and Pratt & Whitney (P&W) to address these questions. The analyses have consisted of two-dimensional axisymmetric calculations done at Marshall Space Flight Center and three-dimensional calculations performed at P&W. These analyses have identified flowfield differences between the baseline ATP and the Rocketdyne configurations. The results show that the baseline ATP configuration represents a more severe environment to the inner HX guide vane. This vane has limited life when tested in conjunction with the ATP but infinite life when tested with the current SSME HPOTP. The CFD results have helped interpret test results and have been used to assess proposed redesigns. This paper includes details of the axisymmetric model, its results, and its contribution towards resolving the problem.

Milestones in the development of computational aerodynamics are reviewed together with past, present, and future computer performance (speed and memory) trends. Factors influencing computer performance requirements for both steady and unsteady flow simulations are identified. Estimates of computer speed and memory that are required to calculate both inviscid and viscous, steady and unsteady flows about airfoils, wings, and simple wing body configurations are presented and compared to computer performance which is either currently available, or is expected to be available before the end of this decade. Finally, estimates of the amounts of computer time that are required to determine flutter boundaries of airfoils and wings at transonic Mach numbers are presented and discussed.

The feasibility of using hypercube-connected concurrent processor systems for problems in computational fluid dynamics is studied. Both explicit and implicit numerical methods are considered and several alternative implementations of these methods are evaluated on concurrent processor systems. A Lax-Wendroff explicit method was designed and implemented for the Navier-Stokes equations. The code runs on the Intel iPSC concurrent processor system. Tests of this code show that it is reasonably efficient. The Beam and Warming implicit factored method was designed and implemented for Berger's equation. Preliminary tests show that the efficiency of code is poor.

The introduction of the supercomputer and recent advances in both Reynolds averaged, and large eddy simulation fluid flow approximation techniques to the Navier-Stokes equations, have created a robust environment for the exploration of problems of interest to the Navy in general, and the Naval Underwater Systems Center in particular. The nature of problems that are of interest, and the type of resources needed for their solution are addressed. The goal is to achieve a good engineering solution to the fluid-structure interaction problem. It is appropriate to indicate that a paper by D. Champman played a major role in developing the interest in the approach discussed.

Alexander the Great was one of the most successful military commanders in history, and was undefeated in battle. By the time of his death, he had conquered most of the world known to the ancient Greeks.<br></br>Alexander the Great is one of many biographies aimed at young people written by Jacob Abbott and his brother. The biographies are written in such a way that makes them appealing and easily accessible to everyone. - Written by Wikipedia and Lizzie Driver

2Peter the Great

By Jacob Abbott

There are very few persons who have not heard of the fame of Peter the Great, the founder, as he is generally regarded by mankind, of Russian civilization. The celebrity, however, of the great Muscovite sovereign among young persons is due in a great measure to the circumstance of his having repaired personally to Holland, in the course of his efforts to introduce the industrial arts among his people, in order to study himself the art and mystery of shipbuilding, and of his having worked with his own hands in a ship-yard there. The little shop where Peter pursued these practical studies still stands in Saardam, a ship-building town not far from Amsterdam. The building is of wood, and is now much decayed; but, to preserve it from farther injury, it has been encased in a somewhat larger building of brick, and it is visited annually by great numbers of curious travelers.<br></br>The whole history of Peter, as might be expected from the indications of character developed by this incident, forms a narrative that is full of interest and instruction for all. (from the Preface of <i>Peter the Great</i>)

3Little Eve Edgarton

By Eleanor Hallowell Abbott

Eve Edgarton is not who she seems she is. A short encounter with Mr. Barton show that first impressions are not always right or indicative of one's seemingly obvious preference or one's proclivity. (Summary by Kehinde)

4Peace On Earth, Good-Will to Dogs

By Eleanor Hallowell Abbott

If you don't like Christmas stories, don't read this one!<br></br> And if you don't like dogs, I don't know just what to advise you to do!<br></br> For I warn you perfectly frankly that I am distinctly pro-dog and distinctly pro-Christmas, and would like to bring to this little story whatever whiff of fir-balsam I can cajole from the make-believe forest in my typewriter, and every glitter of tinsel, smudge of toy candle, crackle of wrapping paper, that my particular brand of brain and ink can conjure up on a single keyboard! And very large-sized dogs shall romp through every page! And the mercury shiver perpetually in the vicinity of zero! And every foot of earth be crusty-brown and bare with no white snow at all till the very last moment when you'd just about given up hope! And all the heart of the story is very,—oh very young!<br></br> For purposes of propriety and general historical authenticity there are of course parents in the story. And one or two other oldish persons. But they all go away just as early in the narrative as I can manage it.—Are obliged to go away!<br></br> Yet lest you find in this general combination of circumstances some sinister threat of audacity, let me conventionalize the story at once by opening it at that most conventional of all conventional Christmas-story hours,—the Twilight of Christmas Eve." (excerpt from the text)

5Molly Make-Believe

By Eleanor Hallowell Abbott

Carl Stanton is an invalid suffering from an unusual bout of rheumatism. His fiancee is gone for the winter and though he begs her to write to help ease his boredom and pain she is stingy with her letters. She sends him what she calls a 'ridiculous circular' which she states is very apropos of his sentimental passion for letters. In a sudden fit of mischief, malice and rheumatism, Carl decides to respond to the circular which results in bringing about the necessary distraction in a flurry of letters that do ease Carl's boredom and pain but also bring him something else that he never quite expected. (summary by Kehinde)

6Indiscreet Letter

By Eleanor Hallowell Abbott

Three fellow travelers on a train enter into a discussion concerning what they would call an 'indiscreet letter.' The discussion, albeit short, produces some rather interesting revelations during the journey and at journey's end. (Summary by Kehinde)

7Seven Wives and Seven Prisons; Or, Experiences in the Life of a Matrimonial Monomaniac

By L. A. Abbott

This work the author claims is indeed a true story of how he happened to be married seven times to seven different women and the rollicking, hilarious events that led (or stumbled) to the marriages and the ah--disassembling/failing/failures of each said marriage which happened oftentimes to land him in prison. The summarist finds the work a very tongue-in-cheek diatribe/lament/account of his obsessive zeal in 'marrying the right one', but is also the mirthful chronicle of said author's very unconventional adventures. (Summary by Kehinde)

8White Linen Nurse

By Eleanor Hallowell Abbott

The White Linen Nurse is a hysterical story of an exhausted nurse who comes to regret her profession and then somehow finds herself caring for the invalid daughter of the Senior Surgeon. The unexpected events which lead her there and also those which take her forward from that point are sure to evoke laughter and tears - a never to be forgotten story that will send a warm glow to your heart. (Summary by Kehinde)

9Cleopatra

By Jacob Abbott

A biography of the famous Cleopatra of Egypt, written in a manner, equally interesting to children and to adults.

<i>Flatland: A Romance of Many Dimensions</i> is an 1884 science fiction novella by the English schoolmaster Edwin Abbott Abbott. As a satire, <i>Flatland</i> offered pointed observations on the social hierarchy of Victorian culture. However, the novella's more enduring contribution is its examination of dimensions; in a foreword to one of the many publications of the novella, noted science writer Isaac Asimov described <i>Flatland</i> as "The best introduction one can find into the manner of perceiving dimensions." As such, the novella is still popular amongst mathematics, physics and computer science students. (Summary by Wikipedia)

There are certain names which are familiar, as names, to all mankind; and every person who seeks for any degree of mental cultivation, feels desirous of informing himself of the leading outlines of their history, that he may know, in brief, what it was in their characters or their doings which has given them so widely-extended a fame. Consequently, great historical names alone are selected; and it has been the writer's aim to present the prominent and leading traits in their characters, and all the important events in their lives, in a bold and free manner, and yet in the plain and simple language which is so obviously required in works which aim at permanent and practical usefulness. This volume is dedicated to William the Conqueror. (Summary from the preface of the book)

There are certain names which are familiar, as names, to all mankind; and every person who seeks for any degree of mental cultivation, feels desirous of informing himself of the leading outlines of their history, that he may know, in brief, what it was in their characters or their doings which has given them so widely-extended a fame. Consequently, great historical names alone are selected; and it has been the writer's aim to present the prominent and leading traits in their characters, and all the important events in their lives, in a bold and free manner, and yet in the plain and simple language which is so obviously required in works which aim at permanent and practical usefulness. This volume is dedicated to Queen Elizabeth. (Summary from the preface of the book)

There are certain names which are familiar, as names, to all mankind; and every person who seeks for any degree of mental cultivation, feels desirous of informing himself of the leading outlines of their history, that he may know, in brief, what it was in their characters or their doings which has given them so widely-extended a fame. Consequently, great historical names alone are selected; and it has been the writer's aim to present the prominent and leading traits in their characters, and all the important events in their lives, in a bold and free manner, and yet in the plain and simple language which is so obviously required in works which aim at permanent and practical usefulness. This volume is dedicated to Richard I. (Summary from the preface of the book)

There are certain names which are familiar, as names, to all mankind; and every person who seeks for any degree of mental cultivation, feels desirous of informing himself of the leading outlines of their history, that he may know, in brief, what it was in their characters or their doings which has given them so widely-extended a fame. Consequently, great historical names alone are selected; and it has been the writer's aim to present the prominent and leading traits in their characters, and all the important events in their lives, in a bold and free manner, and yet in the plain and simple language which is so obviously required in works which aim at permanent and practical usefulness. This volume is dedicated to Mary Queen of Scots. (Summary from the preface of the book)

There are certain names which are familiar, as names, to all mankind; and every person who seeks for any degree of mental cultivation, feels desirous of informing himself of the leading outlines of their history, that he may know, in brief, what it was in their characters or their doings which has given them so widely-extended a fame. Consequently, great historical names alone are selected; and it has been the writer's aim to present the prominent and leading traits in their characters, and all the important events in their lives, in a bold and free manner, and yet in the plain and simple language which is so obviously required in works which aim at permanent and practical usefulness. This volume is dedicated to Charles I. (Summary from the preface of the book)

There are certain names which are familiar, as names, to all mankind; and every person who seeks for any degree of mental cultivation, feels desirous of informing himself of the leading outlines of their history, that he may know, in brief, what it was in their characters or their doings which has given them so widely-extended a fame. Consequently, great historical names alone are selected; and it has been the writer's aim to present the prominent and leading traits in their characters, and all the important events in their lives, in a bold and free manner, and yet in the plain and simple language which is so obviously required in works which aim at permanent and practical usefulness. This volume is dedicated to Hannibal. (Summary from the preface of the book)

17Daniel Boone

By John Stevens Cabot Abbott

This is a detailed biography of the life and adventures of Daniel Boone. His accomplishments are brushed over in history classes these days and not given the recognition they deserve. This biography clearly paints a picture of the benevolent person of Daniel Boone as well as the achievements he made in furthering European settlement in America. (Summary by Allyson Hester)

Throughout three years of school, Rae Malgregor had been perfectly pliant, perfectly compliant to all the demands placed on her. But now, on the eve of graduation, she couldn’t go on with the mask of artificiality and the air of perfection. She had been chasing this nursing job three whole years, but there was just no wag to it! The Superintendent was stunned. Her best student! The Senior Surgeon was all grey granite business and livid that his time was being taken up with a hysterical nurse! And yet, though he wouldn’t have admitted it to anyone, especially himself, his interest was piqued. (Introduction by MaryAnn)

19Romulus

By Jacob Abbott

Jacob Abbott wrote many historical books for children. He was careful to ensure historical accuracy, and as he said himself in the preface to this book "Whatever of interest ... these stories may possess is due solely to the facts themselves which are recorded in them, and to their being brought together in a plain, simple, and connected narrative."<br /><br />This is the story of Romulus, the founding of Rome and the early years of its history, written in a way both readable and enjoyable for adults and children alike. (Summary by Ruth Golding)