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This research describes a computational study undertaken to determine the effect of a flow control mechanism and its associated aerodynamics for a finned projectile. The flow control system consists of small microflaps located between the rear fins of the projectile. These microflaps alter the flow field in the finned region of the projectile, resulting in asymmetric pressure distribution and thus producing control forces and moments. A number of different geometric parameters, microflap locations, and the number of microflaps were varied in an attempt to maximize the control authority generated by the flaps. Steady-state Navier-Stokes computations were performed to obtain the control aerodynamic forces and moments associated with the microflaps. These results were used to optimize the control authority at a supersonic speed, M = 2.5. Computed results not only showed the microflaps to be effective at this speed, but also 6 and 8 microflaps were found to generate 25% 50% more control force than a baseline 4-flap configuration. These results led to a new optimized 8-flap configuration that was further investigated for a range of Mach numbers from M = 0.8 to 5.0 and was found to be a viable configuration effective in providing control at all of these speeds.

The mechanism by which tuna achieve very fast swimming speeds is not presently understood, and may involve delay of transition or an advanced propulsion mechanism (or both). The issue of whether the boundary layer on a tuna swimming at typical speeds (1 to 2 bodylengths/sec) is laminar, turbulent, or transitional is an open question. Using an arc-length Reynolds number (ReL) to estimate the nature of the boundary layer and predict when transition occurs only serves as a rough approximation. Uncertainties include the surface roughness of the skin, local favorable and adverse pressure gradients, and discontinuities such as the open mouth or juncture at the fins. The primary objectives of this project are to compute the approximate lateral location at which transition to turbulence occurs on the tuna for various swimming speeds, and to determinethe maximum speed at which laminar flow is retained on the tunas body. Two-dimensional (2D) and three-dimensional (3D) computer models are used to compute the boundary layer characteristics and predict the lateral location of turbulence onset. The computations cover speeds ranging from 2 to 22 m/s.

Viscous fluid flow is often smooth in most of the domain, with regions of rapid variation confined to some rather narrow zones in the field. These zones (boundary layers, shocks, etc.) cause problems during numerical solution of the equations governing the flow. The patched adaptive mesh refinement technique, devised at Stanford by Oliger, et al., copes with these sources of error efficiently by refining the computational grid locally. This is done by creating separate fine grids for every region of large error. Because of the success of this approach, a project was started to extend its applicability to geometrically complex domains. As patched adaptive mesh refinement already entails multiple grids, it was decided that geometrical complexity would also be tacked using several grids. An arbitrarily shaped domain typically cannot be covered by a single grid without severe distortion, but a covering can be established with only mildly curved grids if more than one grid is allowed. Communication between these grids then becomes an issue, as well as their creation. In this project various types of communications between grids, based on the Schwarz Alternating Procedure (SWAP), are examined for solving steady, two-dimensional incompressible-flow problems. Of these, the traditional SWAP on sets of overlapping grids works best and gives accurate results, despite the use of nonconservative interpolation procedures between grids. When reentrant problems occur, the pressures between grids may not match. A pressure- communication scheme is devised which solves this difficulty.

This research addressed the development of a parallel computational fluid dynamics unstructured grid generator using Delaunay triangulation. The generator is applied to simple elliptical and cylindrical two-dimensional bodies. The methodologies used included Watson's point insertion algorithm, Holmes and Snyder's point creation algorithm, a discretized surface definition, Anderson's clustering function, and a Laplacian smoother. The first version of the software involved a processor boundary exchange at the end of each iteration with no inter-processor communications during the iterations The second version used inter-processor communication during each iteration instead of the boundary exchange. Version 1 demonstrated a speedup of 1.8 for some portions of the code, but proved to be unscalable for more than two nodes due to the interdependency of the triangular elements. The results of Version 2 were similar. Two distribution methodologies, a simple 360-degree distribution and recursive spectral bisection (RSB), were examined. For the initial grid distribution, the distribution generated by the RSB code would be similar to the distribution generated by the 360-degree methodology and would require significantly more time to execute.

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.

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.

Computational Fluid Dynamics (CFD) is continued in volume 2. The lecture topics are: Modelling mass transfer, chemical reactions and combustion, Modelling conductive, convective and radiative heat transfer and Numerical simulation of heat transfer using PHOENICS, Modelling multiple phase flow and phase change and Applications of multiple phase modeling using FIDAP, Numerical simulation in non-Newtonian fluid mechanics, Modelling of flows with unknown free surfaces and Numerical simulation of coating flows using NEKTON and Dispersion of pollutants.

This report documents efforts, to date, in the transition of the Mississippi State University (MSU), incompressible Reynolds-Averaged Navier-Stokes code (UNCLE). The code is evaluated through replication of previous cases documented by MSU and computation of new cases that include more realistic geometries. A grid-sensitivity study is performed, in which a series of grid types and grid distributions is examined. Comparisons of the computed results with measured data for two submarine hulls are presented.

This report documents efforts, to date, in the transition of the Mississippi State University (MSU), incompressible Reynolds-Averaged Navier-Stokes code (UNCLE). The code is evaluated through replication of previous cases documented by MSU and computation of new cases that include more realistic geometries. A grid-sensitivity study is performed, in which a series of grid types and grid distributions is examined. Comparisons of the computed results with measured data for two submarine hulls are presented.

This report documents efforts, to date, in the transition of the Mississippi State University (MSU), incompressible Reynolds-Averaged Navier-Stokes code (UNCLE). The code is evaluated through replication of previous cases documented by MSU and computation of new cases that include more realistic geometries. A grid-sensitivity study is performed, in which a series of grid types and grid distributions is examined. Comparisons of the computed results with measured data for two submarine hulls are presented.

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.

We introduce a modified and simplified version of the pre-existing fully parallelized three-dimensional Navier--Stokes flow solver known as TPLS. We demonstrate how the simplified version can be used as a pedagogical tool for the study of computational fluid dynamics and parallel computing. TPLS is at its heart a two-phase flow solver, and uses calls to a range of external libraries to accelerate its performance. However, in the present context we narrow the focus of the study to basic hydrodynamics and parallel computing techniques, and the code is therefore simplified and modified to simulate pressure-driven single-phase flow in a channel, using only relatively simple Fortran 90 code with MPI parallelization, but no calls to any other external libraries. The modified code is analysed in order to both validate its accuracy and investigate its scalability up to 1000 CPU cores. Simulations are performed for several benchmark cases in pressure-driven channel flow, including a turbulent simulation, wherein the turbulence is incorporated via the large-eddy simulation technique. The work may be of use to advanced undergraduate and graduate students as an introductory study in computational fluid dynamics, while also providing insight for those interested in more general aspects of high-performance computing.

We introduce a modified and simplified version of the pre-existing fully parallelized three-dimensional Navier--Stokes flow solver known as TPLS. We demonstrate how the simplified version can be used as a pedagogical tool for the study of computational fluid dynamics and parallel computing. TPLS is at its heart a two-phase flow solver, and uses calls to a range of external libraries to accelerate its performance. However, in the present context we narrow the focus of the study to basic hydrodynamics and parallel computing techniques, and the code is therefore simplified and modified to simulate pressure-driven single-phase flow in a channel, using only relatively simple Fortran 90 code with MPI parallelization, but no calls to any other external libraries. The modified code is analysed in order to both validate its accuracy and investigate its scalability up to 1000 CPU cores. Simulations are performed for several benchmark cases in pressure-driven channel flow, including a turbulent simulation, wherein the turbulence is incorporated via the large-eddy simulation technique. The work may be of use to advanced undergraduate and graduate students as an introductory study in computational fluid dynamics, while also providing insight for those interested in more general aspects of high-performance computing.

We introduce a modified and simplified version of the pre-existing fully parallelized three-dimensional Navier--Stokes flow solver known as TPLS. We demonstrate how the simplified version can be used as a pedagogical tool for the study of computational fluid dynamics and parallel computing. TPLS is at its heart a two-phase flow solver, and uses calls to a range of external libraries to accelerate its performance. However, in the present context we narrow the focus of the study to basic hydrodynamics and parallel computing techniques, and the code is therefore simplified and modified to simulate pressure-driven single-phase flow in a channel, using only relatively simple Fortran 90 code with MPI parallelization, but no calls to any other external libraries. The modified code is analysed in order to both validate its accuracy and investigate its scalability up to 1000 CPU cores. Simulations are performed for several benchmark cases in pressure-driven channel flow, including a turbulent simulation, wherein the turbulence is incorporated via the large-eddy simulation technique. The work may be of use to advanced undergraduate and graduate students as an introductory study in computational fluid dynamics, while also providing insight for those interested in more general aspects of high-performance computing.

We introduce a modified and simplified version of the pre-existing fully parallelized three-dimensional Navier--Stokes flow solver known as TPLS. We demonstrate how the simplified version can be used as a pedagogical tool for the study of computational fluid dynamics and parallel computing. TPLS is at its heart a two-phase flow solver, and uses calls to a range of external libraries to accelerate its performance. However, in the present context we narrow the focus of the study to basic hydrodynamics and parallel computing techniques, and the code is therefore simplified and modified to simulate pressure-driven single-phase flow in a channel, using only relatively simple Fortran 90 code with MPI parallelization, but no calls to any other external libraries. The modified code is analysed in order to both validate its accuracy and investigate its scalability up to 1000 CPU cores. Simulations are performed for several benchmark cases in pressure-driven channel flow, including a turbulent simulation, wherein the turbulence is incorporated via the large-eddy simulation technique. The work may be of use to advanced undergraduate and graduate students as an introductory study in computational fluid dynamics, while also providing insight for those interested in more general aspects of high-performance computing.

ABSTRACT A gas turbine can combustor is designed to burn the fuel efficiently while reducing the NOx and CO emissions, and lowering the wall temperature. Environmental challenges with gas turbine include low levels of NOx, CO and soot amongst other pollutants. There is a need for new concepts and technology to satisfy the pollutants emission regulations and to enhance energy conservation. Specifically, ultra-low NOx combustor technology is required to meet the ozone depletion challenge. Researchers now face a challenge of developing dry low-NOx emitting stationary and aero engines. However, any concept for environmental pollution control requires a detailed understanding of the physical and the chemical processes that occur during combustion. In this paper, a three dimensional numerical investigation of the Combustion methane air mixture in a gas turbine can combustor is carried out by using ANSYS. The objective of the study is to understand the combustion phenomena at different planes. The various parameters like air-fuel ratio, velocity of primary air inlet are used to investigate the effects on parameters like combustion chamber on different plane performance and emission. A premixing tube is augmented with the combustion chamber which has a primary air inlet port and three gaseous fuel inlet ports. Air–methane mixture is considered to enter the combustion zone with inlet swirl. The homogeneity of mixture before and after swirl and other important conditions are calculated from simulation and are reported with the help ANSYS FLUENT. Weighted averages of velocity magnitude distribution and mass fractions of methane have been studied at different planes.

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.

Solid oxide fuel cell (SOFC) technology has been of great interest over many years due to its flexibility in using different fuels for operation; including the fundamental fuel i.e. Hydrogen. Various computational and numerical models have been developed along with experimental work to evaluate the performance as well as to identify and overcome the problems faced in the development of SOFC's. In an attempt to achieve efficient operation with respect to design and combined thermal and electrochemical perspective, the main objective of the proposed study is to present a three-dimensional computational model, which will serve as a framework for the analysis and optimization of SOFC's. A three-dimensional model of a tubular SOFC was developed to study the effect of temperature and electrolyte thickness variations on its performance. A commercial Computational Fluid dynamics (CFD) software ANSYS FLUENT 12.0 was used for the development of the model which incorporates an interactive 3-D electro-thermo-chemical fluid flow analysis. The particular model, after validation against experimental observations for selected benchmark cases, was demonstrated to be compatible for intermediate temperature operations using hydrogen as fuel. The performance of the model was analyzed by varying electrolyte thicknesses from 2-100 micrometer. The same model was further evaluated using different fuels such as CH4 (methane) and CO (carbon monoxide), including the modeling of the reformation and the water-gas shift reactions. The results were compared to other computationally less expensive, analytical and empirical models, thus confirming the given model to be used as a basic model for future research on intermediate temperature solid oxide fuel cells.

The aerodynamic characteristics of a vehicle in deep-stall conditions are investigated and the motion of the vehicle is predicted in a self-consistent manner. Three-dimensional unsteady computations of the complete aircraft with prescribed control surface deflections are carried out. Both steady and unsteady flow simulations are performed to map out the lift, drag, and moment as a function of various flight and control surface parameters. The unsteady forces and moments were computed, and the resulting unconstrained trajectory based on the 6-dof model of the vehicle is simulated at high angles of attack.

Volume 2-Computational Fluid dynamics and Wave Propagation; Parallel Computing; Concurrent and Supercomputing; Computational Physics/Computational Chemistry and Evolutionary Systems.

A multidisciplnary effort was undertaken to investigate the effect of aerodynamic loading on the structural integrity of a multiple launch rocket system of interest to the U.S. Army. Computational fluid dynamics (CFD) techniques have been used to obtain numerical solutions for the flow field of a rocket and launcher. Computed results have been obtained for several launch tubes, with the rocket at separation distances of 20, 33, and 66 in. Qualitative flow field features show the surface pressure on the surface of both the projectile and the launcher. The surface pressure data on the launcher was then extracted from the solution files. Software was developed to couple this data to a structural dynamics (SD) solver. CFD results provided the aerodynamic loading component used during the initial portion of the launch sequence. The SD code was subsequently used to calculate stress points on the launcher. These results represent a first step in an effort to generalize and fine tune the CFD/SD interface.

A multidisciplnary effort was undertaken to investigate the effect of aerodynamic loading on the structural integrity of a multiple launch rocket system of interest to the U.S. Army. Computational fluid dynamics (CFD) techniques have been used to obtain numerical solutions for the flow field of a rocket and launcher. Computed results have been obtained for several launch tubes, with the rocket at separation distances of 20, 33, and 66 in. Qualitative flow field features show the surface pressure on the surface of both the projectile and the launcher. The surface pressure data on the launcher was then extracted from the solution files. Software was developed to couple this data to a structural dynamics (SD) solver. CFD results provided the aerodynamic loading component used during the initial portion of the launch sequence. The SD code was subsequently used to calculate stress points on the launcher. These results represent a first step in an effort to generalize and fine tune the CFD/SD interface.

The Air Force SEEK EAGLE Office (AFSEO), Eglin AFB, FL, is the United States Air Force (USAF) authority for weapons certification efforts. AFSEO performs test and evaluation for aircraft/store compatibility certification. Computational fluid dynamics (CFD) is employed to support this process. Determining the flow about an aircraft/store combination can be extremely difficult. Complicated geometry features such as pylons, launchers, grid fins, and internal weapons bays create severe aerothermodynamic and acoustic environments which are challenging to numerically simulate. Rapidly and accurately modeling the trajectory of store separation in a high-volume simulation environment presents an additional challenge. 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 associated with the certification computational environment. Before operational use, all aircraft/store configurations must be certified for safe loading, carriage and jettison/release. AFSEO provides flight certification recommendations which are based on combinations of engineering analysis, ground, and flight testing. Engineering analyses is provided by disciplines in carriage loads, store separations, flutter, ballistics, stability and control, and electromagnetic compatibility, and interference. The AFSEO Computational Aeromechanics Team provides time-critical CFD support for engineering analyses to optimize ground and flight testing This contribution takes the form of carriage aerodynamic loads, store separation predictions, and visualized flow field physics. The knowledge created reduces risk, lowers cost, and speeds the fielding of new weapons. This paper discusses six of the most recently applied AFSEO CFD tasks related to specific aircraft/store investigations and certifications.

A Perkin-Elmer 3250 MPS computer system was purchased. To assure more reliable operation, negotiations to replace this with a model 3280 MPS system were completed. Keywords: Computational fluid dynamics, Instrumentation.

COMPUTATIONAL FLUID DYNAMICS (CFD) ANALYSIS FOR IMPROVING NATURAL VENTILATION IN GREEN BUILDINGS

The invention of cross flow turbine industry from straight blades of the Darrieus turbine was modified by Alexander Gorlov into helical shape. There have been several research projects dealing with the design and analysis for tidal applications. This paper deals with the Numerical analysis of a cross flow hydrokinetic turbine (CFHT) with helical blades. Static analysis with optimum blade velocity and constant pressure conditions was performed for the blade with fixed pitch by using Computational Fluid Dynamics (CFD) in Fluent 15. Solidworks was used to carry out 3D modeling of the turbine. The hydrofoil shape of NACA 0018 was created by the airfoil coordinate database. Two different turbulence models Spalart-Allmaras (One-Equation model) and sst-k (Two –Equation model) were employed to compute and compare the results. Pressure profiles, drag and lift coefficients are calculated under a steady flow of 1.5 m/s.

The invention of cross flow turbine industry from straight blades of the Darrieus turbine was modified by Alexander Gorlov into helical shape. There have been several research projects dealing with the design and analysis for tidal applications. This paper deals with the Numerical analysis of a cross flow hydrokinetic turbine (CFHT) with helical blades. Static analysis with optimum blade velocity and constant pressure conditions was performed for the blade with fixed pitch by using Computational Fluid Dynamics (CFD) in Fluent 15. Solidworks was used to carry out 3D modeling of the turbine. The hydrofoil shape of NACA 0018 was created by the airfoil coordinate database. Two different turbulence models Spalart-Allmaras (One-Equation model) and sst-k (Two –Equation model) were employed to compute and compare the results. Pressure profiles, drag and lift coefficients are calculated under a steady flow of 1.5 m/s.

Introduction Cyclones are widely used to separate solid particles from the fluid phase. Due to the ease of construction, low running costs, and hard-working conditions at high temperatures, people's interest in using cyclones is increasing day by day. Engineers are generally interested in two parameters to perform a complete evaluation of the design and operation of a cyclone. These parameters are the particle collecting efficiency and the pressure drop inside the cyclone. The precise prediction of the pressure drop in cyclone is very important which it is directly related to operating costs. Computational Fluid Dynamics (CFD) is a diversified tool for predicting flow behavior in a wide range of design and operational conditions. Numerical solution of Navier-Stokes equations is the basis of all CFD techniques, which is the result of fast computer upgrades and a better understanding of the numerical resolution of turbulence. Materials and Methods Regarding preliminary experimental tests and understanding the fluid flow, the flow rate of 0.08 kg s -1 was selected as the flow rate. Six levels of inlet velocities 10, 12, 14, 16, 18, and 20 m s -1 were selected for understanding the effect of inlet velocity on the cyclone performance. The measurements were carried out using a hot-air anemometer (TSI-8484model with a resolution of 0.07 m s -1 and an operating range of 0.125 to 50 m s -1 ), and a pressure differential meter instrument (CPE310s-KIMO model) with an accuracy of 0.1 Pa. The region is discretized as a finite volume in a set, called the region grid or mesh after discretization. For incompressible fluids, pressure-based and density-based solvers are used, respectively. Regarding the velocity of the material entering the cyclone and low Mach number, a pressure-based solver could be used in this study. The shear stress transport model (SST) is a modified version of the k-ω 2-equation model. This model combines the two turbulence k-ω and k-ε models. The Lagrangian discrete phase model in Ansys Fluent follows to the Euler-Lagrangian model. Defining the best type of boundary condition is important for solving the problem and extracting solving fields. The boundary conditions used in this study include the inlet velocity in the entrance of cyclone and output pressure in both the upper and lower output sections. Results and Discussion In the results section, the results are initially validated by experimental results. Then, the parameters relating to separation efficiency and pressure drop are discussed. Finally, the tangential and axial velocities are considered as important parameters in the cyclone performance. One of the important issues in the cyclones is the static pressure because it completely affects the phenomenon of separation in the cyclone. The velocities of 16 m s -1 and 18 m s -1 have a good potential for use as the base velocity of the inlet fluid to the cyclone. The velocity of 20 m s -1 is not suitable for separation due to high-pressure drop related to high static pressure. The separation efficiency in the cyclone was 92 to 99% at all levels, the highest separation efficiency of 99% occurred at the velocity of 16 m s -1 and the lowest separation efficiency of 9% happened at the velocity of 20 m s -1 . An increasing trend in axial and radial velocities occurred and the highest tangential velocity occurring in the input section. Considering the working conditions, the inlet velocities of 10 m s -1 to 16 m s -1 are appropriate for the turbulence intensity viewpoint. Conclusion (1): The speeds 16 m s -1 and 18 m s -1 showed a good potential for use as a base velocity of the fluid to the cyclone. (2): The highest separation efficiency for the velocity of 16 m s -1 (99%) and lower isolation efficiency was obtained at velocity of 20 m s -1 (92%). (3): The velocities of 10 m s -1 to 16 m s -1 are suitable input rates from the point of view of turbulence intensity. (4): It is concluded that from the point of view of wear to the velocity of 10 to 16 m s -1 , practical use is possible, and the velocity of 18 m s -1 and 20 m s -1 require the reinforcement of the relevant sections.

Introduction Cyclones are widely used to separate solid particles from the fluid phase. Due to the ease of construction, low running costs, and hard-working conditions at high temperatures, people's interest in using cyclones is increasing day by day. Engineers are generally interested in two parameters to perform a complete evaluation of the design and operation of a cyclone. These parameters are the particle collecting efficiency and the pressure drop inside the cyclone. The precise prediction of the pressure drop in cyclone is very important which it is directly related to operating costs. Computational Fluid Dynamics (CFD) is a diversified tool for predicting flow behavior in a wide range of design and operational conditions. Numerical solution of Navier-Stokes equations is the basis of all CFD techniques, which is the result of fast computer upgrades and a better understanding of the numerical resolution of turbulence. Materials and Methods Regarding preliminary experimental tests and understanding the fluid flow, the flow rate of 0.08 kg s -1 was selected as the flow rate. Six levels of inlet velocities 10, 12, 14, 16, 18, and 20 m s -1 were selected for understanding the effect of inlet velocity on the cyclone performance. The measurements were carried out using a hot-air anemometer (TSI-8484model with a resolution of 0.07 m s -1 and an operating range of 0.125 to 50 m s -1 ), and a pressure differential meter instrument (CPE310s-KIMO model) with an accuracy of 0.1 Pa. The region is discretized as a finite volume in a set, called the region grid or mesh after discretization. For incompressible fluids, pressure-based and density-based solvers are used, respectively. Regarding the velocity of the material entering the cyclone and low Mach number, a pressure-based solver could be used in this study. The shear stress transport model (SST) is a modified version of the k-ω 2-equation model. This model combines the two turbulence k-ω and k-ε models. The Lagrangian discrete phase model in Ansys Fluent follows to the Euler-Lagrangian model. Defining the best type of boundary condition is important for solving the problem and extracting solving fields. The boundary conditions used in this study include the inlet velocity in the entrance of cyclone and output pressure in both the upper and lower output sections. Results and Discussion In the results section, the results are initially validated by experimental results. Then, the parameters relating to separation efficiency and pressure drop are discussed. Finally, the tangential and axial velocities are considered as important parameters in the cyclone performance. One of the important issues in the cyclones is the static pressure because it completely affects the phenomenon of separation in the cyclone. The velocities of 16 m s -1 and 18 m s -1 have a good potential for use as the base velocity of the inlet fluid to the cyclone. The velocity of 20 m s -1 is not suitable for separation due to high-pressure drop related to high static pressure. The separation efficiency in the cyclone was 92 to 99% at all levels, the highest separation efficiency of 99% occurred at the velocity of 16 m s -1 and the lowest separation efficiency of 9% happened at the velocity of 20 m s -1 . An increasing trend in axial and radial velocities occurred and the highest tangential velocity occurring in the input section. Considering the working conditions, the inlet velocities of 10 m s -1 to 16 m s -1 are appropriate for the turbulence intensity viewpoint. Conclusion (1): The speeds 16 m s -1 and 18 m s -1 showed a good potential for use as a base velocity of the fluid to the cyclone. (2): The highest separation efficiency for the velocity of 16 m s -1 (99%) and lower isolation efficiency was obtained at velocity of 20 m s -1 (92%). (3): The velocities of 10 m s -1 to 16 m s -1 are suitable input rates from the point of view of turbulence intensity. (4): It is concluded that from the point of view of wear to the velocity of 10 to 16 m s -1 , practical use is possible, and the velocity of 18 m s -1 and 20 m s -1 require the reinforcement of the relevant sections.

The shared-memory programming model is a very effective way to achieve parallelism on shared memory parallel computers. As great progress was made in hardware and software technologies, performance of parallel programs with compiler directives has demonstrated large improvement. The introduction of OpenMP directives, the industrial standard for shared-memory programming, has minimized the issue of portability. In this study, we have extended CAPTools, a computer-aided parallelization toolkit, to automatically generate OpenMP-based parallel programs with nominal user assistance. We outline techniques used in the implementation of the tool and discuss the application of this tool on the NAS Parallel Benchmarks and several computational fluid dynamics codes. This work demonstrates the great potential of using the tool to quickly port parallel programs and also achieve good performance that exceeds some of the commercial tools.

The main objective of this present investigation is to design and analyse pump impeller to give better performance than the existing once. Designing impellers are important for fluid flow analysis for a pump. The impeller of an existing industrial pump was analysed and redesigned using an integrated, design/analysis, turbo machinery geometry modelling and flow simulation system. The purpose of the redesign was to achieve improved impeller performance. To improve the efficiency of pump, computational fluid dynamics (CFD) analysis is one which is used in the pump industry. In the present model Acrylonitrile butadiene styrene (ABS) material is used to reduce noise and cutting down the cost of the impeller. The number of impeller blades is proposed to increase from 6-8 to 16 in order to increase fluid velocity. Inlet blade angle is reduced to less than 35 degrees from greater than 55 degrees to increase efficiency and outlet fluid velocity of the impeller. From the CFD analysis to calculate the efficiency of the existing impeller by using the empirical relations. In the first case outlet angle is increased, and in the second case inlet angle is decreased and they are obtained from the CFD analysis. 

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.

We present a pedagogical review of some of the methods employed in Eulerian computational fluid dynamics (CFD). Fluid mechanics is governed by the Euler equations, which are conservation laws for mass, momentum, and energy. The standard approach to Eulerian CFD is to divide space into finite volumes or cells and store the cell-averaged values of conserved hydro quantities. The integral Euler equations are then solved by computing the flux of the mass, momentum, and energy across cell boundaries. We review both first-order and second-order flux assignment schemes. All linear schemes are either dispersive or diffusive. The nonlinear, second-order accurate total variation diminishing (TVD) approach provides high resolution capturing of shocks and prevents unphysical oscillations. We review the relaxing TVD scheme, a simple and robust method to solve systems of conservation laws like the Euler equations. A 3-D relaxing TVD code is applied to the Sedov-Taylor blast wave test. The propagation of the blast wave is accurately captured and the shock front is sharply resolved. We apply a 3-D self-gravitating hydro code to simulating the formation of blue straggler stars through stellar mergers and present some numerical results. A sample 3-D relaxing TVD code is provided in the appendix.

The ability to enhance detonation wave transmission at a diffraction plane through various shock reflection/focusing conditions was evaluated numerically. The geometry dimensions were generally representative of the condition existing in a valve-less pulse detonation engine developed by the Naval Postgraduate School and consisted of a small cylindrical \"initiator\" combustor, which transmitted a shock wave to a larger diameter combustor. The wall cross section of the larger combustor was varied to evaluate the increase in reflected shock temperature and pressure conditions, ultimately revealing the dramatic increase in local temperature for a \"scalloped\" outer wall condition over the cylindrical cross section cases. The initiator diameter was held constant and the larger combustor diameters varied in order to evaluate the effects of diameter ratio on the shock reflection conditions for both cylindrical and scalloped geometries. A computational fluid dynamics (CFD) solver known as OVERFLOW was used to model the fluid dynamic processes but was limited in capability to shock wave Mach numbers less than about 4.2.

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.

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.

There are 80 million light trucks on the road today with suboptimal aerodynamic forms. Previous research has found that several miles per gallon can be saved by specifically tailoring truck bodies for reduced aerodynamic drag. Even greater savings can be obtained if the shape of the trucks is numerically optimized. This could reduce fuel consumption in the United States by billions of gallons per year. The purpose of this research is to develop and quantify optimal light truck canopy designs using computational fluid dynamics (CFD). Both two-dimensional and three-dimensional models are used to do this. Initially, this research focuses on quantifying and generalizing the effects of traditional automotive aerodynamic accessories, such as canopies and air dams. Once the effects of various form factors are quantified an optimization of the canopy is performed. This thesis demonstrates a method for drag reduction using CFD and traditional numerical optimization techniques. Lastly, the optimized forms are physically constructed and their effects on fuel economy are compared to the CFD prediction. The results indicate that the CFD formulation provides an accurate predictor for improving fuel economy and drag characteristics. The prototype air dam and optimally shaped canopy generated a 21.23% savings in terms of fuel economy.

CFD is a software application that helps end-users analyze the flow, turbulence, and pressure distribution of liquids and gases, and their interaction with structures. It also helps in predicting fluid flow, mass transfer, chemical reactions, and related phenomena. CFD uses high-speed computers, and various numerical methods and solvers to simulate the flow of fluids (gases and liquids). Simulation refers to the digital prototype of the real-world scenario. This helps detect errors in design before proceeding to production. CFD finds wide ranging applications in industries such as automotive, aerospace and defense, electrical and electronics, and energy. CFDs are used to design fuel systems, engine core compartments, cockpit and cabin ventilation, missiles, submarines, and evaluate aerodynamics in the aerospace and defense industry.

CFD is a software application that helps end-users analyze the flow, turbulence, and pressure distribution of liquids and gases, and their interaction with structures. It also helps in predicting fluid flow, mass transfer, chemical reactions, and related phenomena. CFD uses high-speed computers, and various numerical methods and solvers to simulate the flow of fluids (gases and liquids). Simulation refers to the digital prototype of the real-world scenario. This helps detect errors in design before proceeding to production. CFD finds wide ranging applications in industries such as automotive, aerospace and defense, electrical and electronics, and energy. CFDs are used to design fuel systems, engine core compartments, cockpit and cabin ventilation, missiles, submarines, and evaluate aerodynamics in the aerospace and defense industry.

CFD is a software application that helps end-users analyze the flow, turbulence, and pressure distribution of liquids and gases, and their interaction with structures. It also helps in predicting fluid flow, mass transfer, chemical reactions, and related phenomena. CFD uses high-speed computers, and various numerical methods and solvers to simulate the flow of fluids (gases and liquids). Simulation refers to the digital prototype of the real-world scenario. This helps detect errors in design before proceeding to production. CFD finds wide ranging applications in industries such as automotive, aerospace and defense, electrical and electronics, and energy. CFDs are used to design fuel systems, engine core compartments, cockpit and cabin ventilation, missiles, submarines, and evaluate aerodynamics in the aerospace and defense industry.

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%

Computational fluid dynamics (CFD) was used to simulate fluid flow in ducts of varying diameters. Three Transition ducts of equal inlet areas but different outlet diameters were designed and analyzed. Fluid (water) with inlet velocity of 0.12m/s and temperature of 150C (288.15K) was passed adiabatically through the first transition duct of inlet diameter 11.28mm and outlet diameter of 3.57mm. The analyses of the flow reveals a change of approximately 0.1K (-273.05) in temperature in the first duct while the other two ducts also have the same amount of temperature change because of the adiabatic condition of the flow (there was no heat gain or loss by the fluid). Head loss due to pressure variation was recorded as the outlet area changes. The duct with outlet diameter of 3.57mm has minimum pressure of -67.60Pa and maximum pressure of 781.70mm while the second duct with outlet diameter of 6.67mm has - 81.22Pa and 245.30Pa as its minimum and maximum pressure respectively. The last duct with outlet diameter of 8.67mm has -163.70Pa and 319.80Pa as its minimum and maximum pressure respectively.

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NAS 1.55:10038-Vol-2 Digitized from IA1177307-08-0020 , IA1177307-08-0021 , IA1177307-08-0022 , IA1177307-08-0023 , IA1177307-08-0024 , IA1177307-08-0025 .

NAS 1.55:10038-Vol-2 Digitized from IA1177307-08-0020 , IA1177307-08-0021 , IA1177307-08-0022 , IA1177307-08-0023 , IA1177307-08-0024 , IA1177307-08-0025 .