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The computational science community is reluctant to write large-scale computationally -intensive applications in Java due to concerns over Java's poor performance, despite the claimed software engineering advantages of its object-oriented features. Naive Java implementations of numerical algorithms can perform poorly compared to corresponding Fortran or C implementations. To achieve high performance, Java applications must be designed with good performance as a primary goal. This paper presents the object-oriented design and implementation of two real-world applications from the field of Computational Fluid Dynamics (CFD): a finite-volume fluid flow solver (LAURA, from NASA Langley Research Center), and an unstructured mesh adaptation algorithm (2D_TAG, from NASA Ames Research Center). This work builds on our previous experience with the design of high-performance numerical libraries in Java. We examine the performance of the applications using the currently available Java infrastructure and show that the Java version of the flow solver LAURA performs almost within a factor of 2 of the original procedural version. Our Java version of the mesh adaptation algorithm 2D_TAG performs within a factor of 1.5 of its original procedural version on certain platforms. Our results demonstrate that object-oriented software design principles are not necessarily inimical to high performance.

The computational science community is reluctant to write large-scale computationally -intensive applications in Java due to concerns over Java's poor performance, despite the claimed software engineering advantages of its object-oriented features. Naive Java implementations of numerical algorithms can perform poorly compared to corresponding Fortran or C implementations. To achieve high performance, Java applications must be designed with good performance as a primary goal. This paper presents the object-oriented design and implementation of two real-world applications from the field of Computational Fluid Dynamics (CFD): a finite-volume fluid flow solver (LAURA, from NASA Langley Research Center), and an unstructured mesh adaptation algorithm (2D_TAG, from NASA Ames Research Center). This work builds on our previous experience with the design of high-performance numerical libraries in Java. We examine the performance of the applications using the currently available Java infrastructure and show that the Java version of the flow solver LAURA performs almost within a factor of 2 of the original procedural version. Our Java version of the mesh adaptation algorithm 2D_TAG performs within a factor of 1.5 of its original procedural version on certain platforms. Our results demonstrate that object-oriented software design principles are not necessarily inimical to high performance.

The computational science community is reluctant to write large-scale computationally -intensive applications in Java due to concerns over Java's poor performance, despite the claimed software engineering advantages of its object-oriented features. Naive Java implementations of numerical algorithms can perform poorly compared to corresponding Fortran or C implementations. To achieve high performance, Java applications must be designed with good performance as a primary goal. This paper presents the object-oriented design and implementation of two real-world applications from the field of Computational Fluid Dynamics (CFD): a finite-volume fluid flow solver (LAURA, from NASA Langley Research Center), and an unstructured mesh adaptation algorithm (2D_TAG, from NASA Ames Research Center). This work builds on our previous experience with the design of high-performance numerical libraries in Java. We examine the performance of the applications using the currently available Java infrastructure and show that the Java version of the flow solver LAURA performs almost within a factor of 2 of the original procedural version. Our Java version of the mesh adaptation algorithm 2D_TAG performs within a factor of 1.5 of its original procedural version on certain platforms. Our results demonstrate that object-oriented software design principles are not necessarily inimical to high performance.

The computational science community is reluctant to write large-scale computationally -intensive applications in Java due to concerns over Java's poor performance, despite the claimed software engineering advantages of its object-oriented features. Naive Java implementations of numerical algorithms can perform poorly compared to corresponding Fortran or C implementations. To achieve high performance, Java applications must be designed with good performance as a primary goal. This paper presents the object-oriented design and implementation of two real-world applications from the field of Computational Fluid Dynamics (CFD): a finite-volume fluid flow solver (LAURA, from NASA Langley Research Center), and an unstructured mesh adaptation algorithm (2D_TAG, from NASA Ames Research Center). This work builds on our previous experience with the design of high-performance numerical libraries in Java. We examine the performance of the applications using the currently available Java infrastructure and show that the Java version of the flow solver LAURA performs almost within a factor of 2 of the original procedural version. Our Java version of the mesh adaptation algorithm 2D_TAG performs within a factor of 1.5 of its original procedural version on certain platforms. Our results demonstrate that object-oriented software design principles are not necessarily inimical to high performance.

Computational fluid dynamics (CFD) is a  branch of fluid mechanics  that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows.

Computational fluid dynamics (CFD) is a  branch of fluid mechanics  that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows.

Computational fluid dynamics (CFD) is a  branch of fluid mechanics  that uses numerical analysis and data structures to analyze and solve problems that involve fluid flows.

Anatomically accurate computational fluid dynamics (CFD) models of the nasal passages of an infant (6 months old, 1.3 kg) and adult (7 years old, 11.9 kg) rhesus monkey were used to predict deposition of inhaled nano- and micro-particles. Steady-state, inspiratory airflow simulations were conducted in each model at flow rates equal to 100%, 200%, and 300% of the estimated minute volume for resting breathing. Particle transport and deposition simulations were conducted using the Lagrangian method to track the motion of individual particles that were passively released from the nostrils. Semi-empirical curves for nasal deposition were developed based on the simulation data for nano- and micro-particle deposition to allow for simplified calculations of age-based nasal deposition in the rhesus monkey nasal passages that can be implemented into lung dosimetry models.

Validation Of Computational Flight Dynamics was the subject of the 62 nd Meeting of the Fluid Dynamics Panel. The Call-for-Papers was focused on a compilation of the State of Art of Validation of computer codes, to insure, that the mathematical and numerical schemes employed in the code model correctly the critical physics of the flow field. This ambitious aim was reached only to a degree by comparison of experimental and computational data. But at least some of the papers have attempted to validate computer codes by the use of recently developed Data Bases providing also detailed information on 3D-flow field characteristics. The reviewer summarizes the papers, comments on the overall program, and tries to identify existent gaps for future work. The ultimate goal of CFD development is a fully mature design and analysis capability, that is user friendly, cost effective, numerical accurate and fully verified by detailed experimental comparisons. CFD code validation is accomplished by detailed flow field comparison numerical solutions with experimental data to insure that the mathematical and numerical schemes employed in the code accurately model the critical physics of the flow field. The symposium will concentrate on the validation of computational methods. The objectives are to identify the level of agreement of physical models and numerical solution algorithms with experimental data; to identify regions of validity for given flow solvers; and to identify flow regimes where significant gaps exist and further work is warranted.

Symposia contents: Validation of a Multi-Block Euler Flow Solver with Propeller-SlipStream Flows; Investigation of the Surface Flow on Conical Bodies at High Subsonic and Supersonic Speeds; Design and Validation of a 2D Euler Code; Finite Difference Methods in Recirculating Flows; The Design of the Garteur Low Aspect-Ratio Wing for use in the Validation of Shear Layer and Overall Flow Prediction Methods; Slender Cone CFD and Experimental Data Comparisons in Hypersonic Flow; Validation of a User-Friendly CFD Code for Prediction of the Aerodynamic Characteristics of Flight Vehicles; Comparison of Theory and Experiment for Four Supercritical, Low Drag Airfoils; Solution Error Estimation in the Numerical Predictions of Turbulent Recirculating Flows; Detailed Flowfield Measurements Over a 75-Degree Swept Delta Wing for Code Validation; Experiments and Code Validation for Juncture Flows; Accuracy and Efficiency of a Time Marching Approach for Combustor Modeling; Large-Scale Viscous Simulation of Laminar Vortex Flow over a Delta Wing; and Investigation of the Accuracy of Finite Volume Methods For 2-and 3-Dimensional Flows.

A brief non-mathematical introduction to the subject of Computational Fluid Dynamics, (CFD), is given. Various approximations to the full flow equations are described and their suitability for modelling the aerodynamics of missiles is discussed. A number of CFD codes available in the UK which are applicable to missile aerodynamics are considered. Each code is described briefly and comparisons between prediction and measurement are shown. Keywords: Great Britain, Navier stokes equations, Grids, Missile, Configurations.

Using the commercially available FLUENT 3-D flow field solver, this research effort investigated vortex breakdown over a delta wing at high angle of attack (a) in preparation for investigation of active control of vortex breakdown using steady, along- core blowing A flat delta-shaped half-wing with sharp leading edge and sweep angle of 600 was modeled at a 180 in a wind tunnel at Mach 0,04 and Reynolds number of 3,4 x 10(sub 5). A hybrid (combination of structured and unstructured) numerical mesh was generated to accommodate blowing ports on the wing surface. Results for cases without and with along-core blowing included comparison of various turbulence models for predicting both flow field physics and quantitative flow characteristics, FLUENT turbulence models included Spalart-Allmaras (S-A), Renormalization Group k-e, Reynolds Stress (RSM), and Large Eddy Simulation (LES), as well as comparison with laminar and inviscid models. Mesh independence was also investigated, and solutions were compared with experimentally determined results and theoretical prediction, These research results show that, excepting the LES model for which the computational mesh was insufficiently refined and which was not extensively investigated, none of the turbulence models above, as implemented with the given numerical grid, generated a solution which was suitably comparable to the experimental data. Much more work is required to find a suitable combination of numerical grid and turbulence model.

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.

Accurate modeling of near-field wave propagation is critical to determine blast wave overpressure of large caliber muzzle brakes. Experimental testing to determine blast overpressure is costly, making computational fluid dynamics (CFD) simulations of these flow-fields a viable alternative. Techniques and specialized CFD codes are being developed in order to properly model the unsteady, very high-pressure flows of gun muzzle blast. Two CFD codes, Fluent 6.1.11 (a prerelease version of Fluent) and the Discontinuous Galerkin Code (DG) were developed at Rensselaer Polytechnic Institute, Troy, NY. These codes were used to compare experimental shadowgraph data from the 7.62-mm NATO rifle G3 using a DM-41 training round for the purpose of developing CFD modeling techniques and validation of the CFD codes. Unsteady grid adaption was used with both solvers in order to reduce solution error near unsteady blast waves and shocks. It is possible to get good results from Fluent with high levels of adaption, however DG can model blast with courser grid adaption. It was also found that DG required an order-of-magnitude longer solution time than Fluent for a given number of grid elements. The 7.62-mm NATO G3 CFD precursor flow results matched experimental shadowgraph results well, however, the main propellant flow results did not match well.

The Maritime Platforms Division within DSTO is currently studying the science and technology of autonomous underwater vehicles for defence applications. Part of this work involves a study of the hydrodynamics and maneuverability of these vehicles and the development of methods to determine the hydrodynamic coefficients of submerged bodies as a function of their shape. This report describes the application of the FIDAP Computational Fluid Dynamics package to the calculation of lift and drag forces on relatively simple underwater vehicle shapes, including cylinders, spheres, flat plates, and wing profiles. The degree to which FIDAP accurately reproduces known experimental data on these shapes is described and the applicability of other Computational Fluid Dynamics packages is discussed. (13 tables, 2 figures, 38 refs.)

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 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)

The multidisciplinary nature of rotary-wing aeromechanics poses a daunting challenge for the design of practical modeling and simulation software that is accurate, efficient, and maintainable. This paper describes the design strategy for the US Army's Helios software, which features a lightweight Python-language integration framework combined with well-defined interfaces to link together various multidisciplinary software components. This design facilitates the use of alternative component software within Helios, the addition of new component software into Helios, and the rapid introduction of new computational fluid dynamics technology within Helios. This paper also presents examples of Helios rotary-wing aeromechanics simulations that include simultaneous solutions for rotor dynamics and aerodynamics plus high resolution of the rotor wake system.

Validation is often defined as the process of determining the degree to which a model is an accurate representation of the real world from the perspective of its intended uses. Validation is crucial as industries and governments depend increasingly on predictions by computer models to justify their decisions. In this article, we survey the model validation literature and propose to formulate validation as an iterative construction process that mimics the process occurring implicitly in the minds of scientists. We thus offer a formal representation of the progressive build-up of trust in the model, and thereby replace incapacitating claims on the impossibility of validating a given model by an adaptive process of constructive approximation. This approach is better adapted to the fuzzy, coarse-grained nature of validation. Our procedure factors in the degree of redundancy versus novelty of the experiments used for validation as well as the degree to which the model predicts the observations. We illustrate the new methodology first with the maturation of Quantum Mechanics as the arguably best established physics theory and then with several concrete examples drawn from some of our primary scientific interests: a cellular automaton model for earthquakes, an anomalous diffusion model for solar radiation transport in the cloudy atmosphere, and a computational fluid dynamics code for the Richtmyer-Meshkov instability. This article is an augmented version of Sornette et al. [2007] that appeared in Proceedings of the National Academy of Sciences in 2007 (doi: 10.1073/pnas.0611677104), with an electronic supplement at URL http://www.pnas.org/cgi/content/full/0611677104/DC1. Sornette et al. [2007] is also available in preprint form at physics/0511219.

Diesel engines are used in automotive and stationary  applications. The main problem with diesel engines is emissions  of nitrogen oxides (NOx) and particulates. In order to minimize  the emissions, it is necessary to design the diesel engine with  better in-cylinder flow (air-fuel mixing) and combustion  process. Computational Fluid Dynamics (CFD) simulation  helps to understand the Diesel engine temperature distribution  and NOx species concentrations with respect to time. A small  direct injection (DI) engine was chosen for the study. CFD simulation results were compared with that of engine emission tests. Results were found to be in agreement with NOx  emissions. This paper also presents the simulation results of  direct injection diesel engine in-cylinder flow (air-fuel mixing)  and combustion.

Diesel engines are used in automotive and stationary  applications. The main problem with diesel engines is emissions  of nitrogen oxides (NOx) and particulates. In order to minimize  the emissions, it is necessary to design the diesel engine with  better in-cylinder flow (air-fuel mixing) and combustion  process. Computational Fluid Dynamics (CFD) simulation  helps to understand the Diesel engine temperature distribution  and NOx species concentrations with respect to time. A small  direct injection (DI) engine was chosen for the study. CFD simulation results were compared with that of engine emission tests. Results were found to be in agreement with NOx  emissions. This paper also presents the simulation results of  direct injection diesel engine in-cylinder flow (air-fuel mixing)  and combustion.

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.

The fluid dynamics of curved diffuser duct flows of military aircraft is discussed. Three-dimensional parabolized Navier-Stokes analysis, and experiment techniques are reviewed. Flow measurements and pressure distributions are shown. Velocity vectors, and the effects of vortex generators are considered.

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.

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.

Cost-effective vectorization of fluid dynamic codes, in particular the Navier/Stokes Code, is covered relative to the supercomputer architecture. Subjects include current supercomputer architecture; minisupercomputers; impact of hardware on computing; software migration issues; benchmarking; guidelines on Fortran vectorization at the do-loop level; restructuring of basic linear algebra algorithms; and restructuring guidelines for basic fluid dynamic codes. A glossary of supercomputing terms is given in the Appendix.

During the period covered by the Grants attention has been focused on three areas, all of them of importance in the successful application of implicit algorithms to Computational Fluid Dynamics (CFD): 1) The role of boundary conditions for implicit hyperbolic schemes; 2) The stability of hyperbolic Approximate Factorization schemes in three space dimensions; and 3) The rate of convergence to steady state of ADI methods. This report delineates the progress in each of the above enumerated areas. The details of the research will be found in reports and papers as referenced below for each of the tasks.

The International Conference series on Numerical Grid Generation in Computational Fluid Dynamics was started in July 1986 to recognize grid generation as an essential subject of Computational Fluid Dynamics which needs individual attention. The conference is held bi-annually with the purpose of disseminating new ideas, recent advances and difficulties encountered by researchers around the world while solving practical Computational Fluid Dynamics problems. The second conference in the series was held in Miami, Florida, USA, during the week of December 5-9, 1988. The main theme of the conference was 2-D and 3-D adaptive grid methods. Nevertheless, papers were invited from all relevant conventional areas such as algebraic, boundary fit, and conformal mapping methods and other areas including applications in computational mechanics.

A study was conducted to evaluate the accuracy of a commercial computational fluid dynamics (CFD) code (CFDRC-ACE+) for predicting incompressible air jet flows with simple geometries. Specifically, the axis-symmetric and two-dimensional heated air-jets were simulated using a standard k-epsilon turbulence model. These CFD predictions were directly compared to an extensive compilation of experimental data from archive literature. The round jet results indicated that the code over-predicted the velocity-spreading rate by 24% and the temperature spreading rate by 29%.

This report describes a computational study undertaken to consider the aerodynamic effect of small tiny jets as a means to provide the control authority needed to maneuver a projectile at low subsonic speeds. Scalable Navier-Stokes computational techniques have been used to obtain numerical solutions for the jet-interaction flow field for a projectile at subsonic speeds. Computed results have been obtained at low subsonic speeds at 0 deg and 4 deg angle of attack. Both steady and unsteady jets have been considered. For comparison purposes, a jet-off case was also computed. Qualitative flow field features show the interaction of jets with the free stream flow. Numerical results show the effect of the jet locations and sizes on the flow field and surface pressures, and hence on the aerodynamic coefficients. Unsteady jet results have been obtained for a two-dimensional (2-D) jet flow and compared with experimental data for validation. Some results obtained with an unsteady jet for the subsonic projectile are included. These numerical results are being assessed to determine if small tiny jets can be used to provide the control authority needed for maneuvering munitions in lieu of canards and fins.

Computational fluid dynamics (CFD) has made great strides in the detailed simulation of complex fluid flows, including the fluid physics of flows heretofore not understood. It is now being routinely applied to some rather complicated problems, and starting to impact the design cycle of aerospace vehicles and their components. In addition, it is being used to complement and is being complemented by experimental studies. In this paper some major elements of contemporary CFD research, such as code validation, turbulence physics, and hypersonic flows are discussed, along with a review of the principal pacing items that currently govern CFD. Several examples are presented to illustrate the current state of the art. Finally, prospects for the future of the development and application of CFD are suggested.

In aerospace computational fluid dynamics (CFD) calculations, the Delaunay triangulation of suitable quadrilateral meshes can lead to unsuitable triangulated meshes. Here, we present case studies which illustrate the limitations of using structured grid generation methods which produce points in a curvilinear coordinate system for subsequent triangulations for CFD applications. We discuss conditions under which meshes of quadrilateral elements may not produce a Delaunay triangulation suitable for CFD calculations, particularly with regard to high aspect ratio, skewed quadrilateral elements.

Automation of flow field zoning in two dimensions is an important step towards reducing the difficulty of three-dimensional grid generation in computational fluid dynamics. Using a knowledge-based approach makes sense, but problems arise which are caused by aspects of zoning involving perception, lack of expert consensus, and design processes. These obstacles are overcome by means of a simple shape and configuration language, a tunable zoning archetype, and a method of assembling plans from selected, predefined subplans. A demonstration system for knowledge-based two-dimensional flow field zoning has been successfully implemented and tested on representative aerodynamic configurations. The results show that this approach can produce flow field zonings that are acceptable to experts with differing evaluation criteria.

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An anti-vortex baffle is a liquid propellant management device placed adjacent to an outlet of the propellant tank. Its purpose is to substantially reduce or eliminate the formation of free surface dip and vortex, as well as prevent vapor ingestion into the outlet, as the liquid drains out through the flight. To design an effective anti-vortex baffle, Computational Fluid Dynamic (CFD) simulations were undertaken for the NASA Ares I vehicle LOX tank subjected to the simulated flight loads with and without the anti-vortex baffle. The Six Degree-Of-Freedom (6-DOF) dynamics experienced by the Crew Launch Vehicle (CLV) during ascent were modeled by modifying the momentum equations in a CFD code to accommodate the extra body forces from the maneuvering in a non-inertial frame. The present analysis found that due to large moments, the CLV maneuvering has a significant impact on the vortical flow generation inside the tank. Roll maneuvering and side loading due to pitch and yaw are shown to induce swirling flow. The vortical flow due to roll is symmetrical with respect to the tank centerline, while those induced by pitch and yaw maneuverings showed two vortices side by side. The study found that without the anti-vortex baffle, the swirling flow caused surface dip during the late stage of drainage and hence early vapor ingestion. The flow can also be non-uniform in the drainage pipe as the secondary swirling flow velocity component can be as high as 10% of the draining velocity. An analysis of the vortex dynamics shows that the swirling flow in the drainage pipe during the Upper Stage burn is mainly the result of residual vortices inside the tank due to the conservation of angular momentum. The study demonstrated that the swirling flow in the drainage pipe can be effectively suppressed by employing the anti-vortex baffle.

The needs for Computational Fluid Dynamics (CFD) in connection with student and faculty activities in the engineering departments at NPS are reviewed. Emphasis is placed on internal, propulsion related flows. Currently available CFD codes are also reviewe

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 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.

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.

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.

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.

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

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.