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The overall goal of this research was the development and application of covolume methodology in CFD and related areas. The main framework of the covolume approach is now in place and its major characteristics are reasonably well understood. The research shows the algorithm to be a stable and accurate approach to computing viscous fluids on unstructured meshes. The covolume approach has several unique features, including an associated discrete vector field theory, which in turn permits covolume discretizations to exhibit important physical characteristics, for example being free of artificial vorticity creation. There is still need for work in compressible and three dimensional flows.

This research concerns projects of seven investigators at the University of Pittsburgh relating to the general area of computational fluid dynamics. Topics include the dual variable method, Differential Algebraic Equation, the reduced basis method, divergence free finite elements, diffusive- transport systems, and bifurcation phenomena. Short descriptions of these projects are included, along with references to published reports. (jg)

Research is directed at the application of modern computer technologies, with emphasis on emerging parallel computing techniques to the solution of fluid dynamic problems. CFD algorithms will be developed, implemented, analyzed and benchmarked on several different architecture parallel computers. Keywords: Parallel processing, Algorithms, Domain decomposition.

Algorithm development. Implementation of a 3-D Navier Stokes implicit research code for AFFDL was initiated. This required the parallel solution of block-tridiagonal system and so was more challenging than the above explicit code. This is being continued in a new AFOSR grant. Connection Machine experiments. To keep abreast of SIMD architecture performance, a series of Fortran and C kerrels were studies on the Argonne Laboratory CM-2 during the summer of 1989. It was concluded that the available Fortran 8X implementation of the CM-2 was too inefficient to warrant continued at that time. Keywords: Programming languages; Computer programming; Computer architecture.

The propagation characteristics of several helicopter airfoil profiles have been investigated using the transonic small disturbance equation. A test case was performed to generate a moving shock that propagated off the airfoil. Various grids were then examined to determine their ability to accurately capture these propagating shock waves. Finally, the case of airfoil vortex interactions was thoroughly studied over a wide range of Mach numbers and airfoil shapes with particular emphasis on the transonic regime; this results in a highly complicated fluctuation of lift, drag, and pitching moment. The calculated acoustic intensity levels, along with the details of the computational flow field, provide new insights into the understanding of transonic airfoil vortex interactions.

This research concerned three independent projects of ICMA (Institute of Computational Mathematics and Applications) personnel, each belonging to the general area of computational fluid dynamics. The first project dealt with the computation of stationary Navier-Stokes solutions using continuation methods. Error estimates for certain finite element solutions of continuation problems were derived and extensions to more general operators including the Navier-Stokes operator were investigated. Numerical methods for the detection of Hopf bifurcation were studied. The second project involved construction, analysis and implementation of efficient computer algorithms for the finite difference and finite element-dual variable discretization of the two-dimensional Navier-Stokes problems. Particular attention was given to finite element and finite differences discretization such problems that arise in combustor modeling. The third project sought to extend the dual variable reduction technique to various fluid models. This required the construction of a network analogue for the discrete difference equations along with an analysis of the fundamental matrix and dual variable transformation involved. (Author)

Dynamic mesh adaptation strategies are investigated. These include software development, dynamically adaptive mesh schemes, errors arising from generalized mappings and orthogonality. The strategies developed are tested against the euler and viscous Burgers Equations.

The objectives of this program were to: validate CFD-based OPD model using wavefront sensor data from wind tunnel experiments; exercise CFD model to assess performance of larger, more realistic configuration with conformal window; and determine wavefront control system requirements. CFD validation consisted of: wind tunnel WFS measurements of phase over scaled turret with conformal window; and comparison with CFD-based model at 1:1 scale including wind tunnel boundaries and inlet flow profile. Large scale analysis entailed assessing performance of larger turret with conformal window, and evaluating wavefront control requirements. The program was successfully completed. Turrets were designed and fabricated; wind tunnel tests were conducted; WFS data was collected; the CFD-based aero model was validated; and large scale analysis and wavefront control requirements were completed.

Analytical methods and computational fluid dynamics are used to describe flow conditions encountered at Naval Research Laboratory's Ballast Water Treatment Test Facility. Design tradeoffs are examined in the engineering of sample ports for collecting biological organisms in water samples, and criteria are provided for sample port installation in shipboard piping systems. Results of this work show that the ideal geometry for biological sampling is from the centerline of a straight, vertical, upward-flowing pipe having a sample port diameter between 1.5 and 2.0 times the basic isokinetic diameter as defined in this report. Sample ports should use ball valves for isolation purposes, and diaphragm or venturi valves for flow control; they should be located as close to the overboard outlet as possible; and they should be positioned as far from upstream obstructions and fittings as possible.

The Final Proceedings for Parallel Computational Fluid Dynamics (CFD) Workshop, 16 June 1999 - 18 June 1999. This is an interdisciplinary conference. Topics to include: Turbulent Flows; Multiphysics Flows; Aerodynamic Flows; Multidisciplinary Applications; Parallel Computing in Aerospace and Mechanical Engineering; Parallel and Sequential Grid Partitioning Techniques; Parallel Grid Generation; Load Balancing; Domain Decomposition, etc.

This report describes an overview of the research efforts undertaken to develop a computational fluid dynamics (CFD) tool to analyze flow fields relevant to chemical oxygen/iodine lasers (COIL). In the listed references, computations of the three-dimensional nozzle flow fields with transverse jet injection are described in addition to several two-dimensional computational results, verifying the implementation of the model equations. Improvement in the efficiency of the computations was demonstrated by the use of a grid sequencing approach. (7 refs.)

Quantum-computing ideas are applied to the practical and ubiquitous problem of fluid dynamics simulation. Hence, this paper addresses two separate areas of physics: quantum mechanics and fluid dynamics (or specifically, the computational simulation of fluid dynamics). The quantum algorithm is called a quantum lattice gas. An analytical treatment of the microscopic quantum lattice-gas system is carried out to predict its behavior at the mesoscopic scale. At the mesoscopic scale, a lattice Boltzmann equation with a nonlocal collision term that depends on the entire system wave function, governs the dynamical system. Numerical results obtained from an exact simulation of a one-dimensional quantum lattice model are included to illustrate the formalism. A symbolic mathematical method is used to implement the quantum mechanical model on a conventional work- station The numerical simulation indicates that classical viscous damping is not present in the one-dimensional quantum lattice-gas system.

Early experimental work, conducted at Defence R and D Canada Suffield, measured and characterized the personal and environmental contamination associated with simulated anthrax-tainted letters under a number of different scenarios in order to obtain a better understanding of the physical and biological processes for detecting, assessing, and formulating potential mitigation strategies for managing the risks associated with opening an anthrax-tainted letter. These preliminary experimental investigations have been extended in the present study to simulate the contamination from anthrax-tainted letters in an Open-Office environment using Computational Fluid Dynamics (CFD). A quantity of 0.1 g of a biological simulant Bacillus globigii (BG) for anthrax was released from an opened letter in the experiment. The accuracy of the model for prediction of the spatial distribution of BG spores in the office from the opened letter is assessed qualitatively (and to the extent possible, quantitatively) by detailed comparison with measured BG concentrations obtained under a number of scenarios, some involving people moving within the office. It is hypothesized that the discrepancy between the numerical predictions and experimental measurements of concentration were mainly caused by :(1) air flow leakage from cracks and crevices in the walls and windows of the building shell; (2) decoupling between the present CFD simulation and dispersion of BG spores in the Heating, Ventilation, and Air Conditioning (HVAC) system; (3) the effect of deposition and re-suspension of BG spores not being considered in the present CFD simulations. Although there is still a scope of further improvement in the present CFD simulation, it should be emphasized here that the advantages of utilization of CFD modeling for assessment and design of mitigation strategies and protocols for defence against anthrax-tainted letters over an experimentally based approach to the problem are obvious:

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.

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.

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.

Introduction Greenhouse cultivation is the popular intensive kind of crop production with a yield per cultivated unit area more than 10 times higher compared to field crops. Greenhouse production requires the use of large amounts of energy, water, and pesticides and it usually generates huge quantities of wastes to be disposed of it. Investment, labor, and energy costs per unit area are much higher in the greenhouse industry than in any other agricultural sectors. Sustainable greenhouse systems, socially supportive, commercially competitive, and environmentally sound, depend on cultivation techniques, equipment management, and constructive materials that aim to reduce agrochemicals, energy and water consumption as well as waste generation. The management of the greenhouse environment is depending on temperature manipulation. Temperature manipulation is critical to influencing plant growth, quality, and morphology and so is a major strategy in the environmental modification of crops. Heterogeneous indoor microclimate of a greenhouse has long become a matter of concern in many studies. It is believed to be unfavorable for crop growth, which damages crop activity, particularly transpiration and photosynthesis, one of the major causes of non-uniform production and quality. Since early and conventional methods are not sufficient to evaluate microclimate variables inside a greenhouse, Computational Fluid Dynamics (CFD) approach was applied for better and more accurate results. CFD is an effective numerical analysis technique to predict the distribution of the climatic variables inside cultivation facilities. Numerous studies have focused on the internal temperature, humidity, solar radiation, and airflow inside multiple cultivation facilities. For example, the CFD method was used to simulate natural ventilation for agricultural buildings and improve crop production systems. The CFD simulation and evaluation models could be applied for evaluation of the inside situation and temperature in greenhouses. Thermal and water vapor transfer is influenced by the openings of greenhouses in the CFD simulation. The CFD model was developed to predict the distribution of temperature, water vapor, and CO 2 occurring in a Venlo-type semi-closed glass greenhouse equipped with air conditioners. Based on the above literature, this research aims to evaluate the energy flow and modeling of an un-even semi-buried greenhouse using external and internal variables and numerical solutions by the CFD method. Materials and Methods In this study, Computational Fluid Dynamic (CFD) solution was applied to evaluate the inside environment of a semi-double glass greenhouse with an east-west location. This greenhouse has a special structure that is used in very hot or very cold areas due to its depth of more than one meter below the ground. The greenhouse has an area of 38m 2 and an air volume of 78.8m 3 . The temperature and humidity data were collected from inside and outside the greenhouse by temperature sensors (SHT 11 model made by CMOS USA). Irradiation data were collected inside the greenhouse, on level ground, by the TES132 radiometer. Results and Discussion In this study, the CFD method was used for a model solution with ANSYS Fluent version 2020R2 software. To evaluate the predictive capability of the model and its optimization, the comparison between actual (ya) and predicted values (yp) was used. Three criteria of RMSE, MAPE, and R 2 were also used to evaluate the accuracy of the final model. The results showed that the dynamic model can accurately estimate the temperature of the air inside the greenhouse at a height of 1 m (R 2 = 0.987, MAPE = 2.17%) and 2 m (R 2 = 0.987, MAPE = 2.28%) from the floor. The results of energy flow showed that this greenhouse transfers 6779.4.4 kJ of accumulated thermal energy to the ground during the experiment. Conclusion In the present study, the computational fluid dynamics method was used to simulate the internal conditions of an un-even semi-buried greenhouse with external and internal variables including temperature and solar radiation. The results showed that this greenhouse structure is able to transfer part of the increase in temperature caused by sunlight to the soil depth (104.214 kJm -2 heat through the floor, 178.443 kJm -2 through the north wall and 113.757 kJm -2 through the south wall). By increasing the thermal conductivity of the inner surface of the greenhouse, the heat flux to the depth of the soil can be increased.

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.

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 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.

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.

Channel flows have three components of velocity, 1component in flow direction and 2components in spanwise of Channel. Because of heterogeneity of velocity undulations, in the channel section the vortices are formed that are nominated “Secondary Current Cells”. These cells cause the lateral shear stress in the channel walls and introduce the erosion and scour of the channel walls. Heterogeneity of the turbulency is caused due to boundary conditions of the bed, side wall and free surface, the aspect ratio and the geometry of the channel. The mechanism of secondary currents can be expressed by longitudinal vorticity equation. In this research, the flow in trapezoidal channels has been modeled using the “Computational Fluid Dynamics” (CFD) with “ANSYS CFX” soft ware, and additional to investigation of sufficiency of CFD in modeling of secondary flow cells, depth averaged velocity and boundary shear stress distributions are perused. For this purpose, the experimental model of Tominaga, and analytical model of Shiono and knight has been used to verify the numerical results. The numerical results are in agreement with the experimental and analytical models.

Channel flows have three components of velocity, 1component in flow direction and 2components in spanwise of Channel. Because of heterogeneity of velocity undulations, in the channel section the vortices are formed that are nominated “Secondary Current Cells”. These cells cause the lateral shear stress in the channel walls and introduce the erosion and scour of the channel walls. Heterogeneity of the turbulency is caused due to boundary conditions of the bed, side wall and free surface, the aspect ratio and the geometry of the channel. The mechanism of secondary currents can be expressed by longitudinal vorticity equation. In this research, the flow in trapezoidal channels has been modeled using the “Computational Fluid Dynamics” (CFD) with “ANSYS CFX” soft ware, and additional to investigation of sufficiency of CFD in modeling of secondary flow cells, depth averaged velocity and boundary shear stress distributions are perused. For this purpose, the experimental model of Tominaga, and analytical model of Shiono and knight has been used to verify the numerical results. The numerical results are in agreement with the experimental and analytical models.

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 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 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.

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%

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. 

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.

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 Membrane Bio-Reactor waste-water treatment system,The water production of membrane modules is an important parameter to measure the working efficiency of MBR system, while the internal pressure series MBR is a common membrane module connection method. Therefore, the calculation and analysis of the water production of internal pressure series MBR system by computational fluid dynamics is carried out. In the analysis process, the geometric model of the internal pressure series MBR system is first established by the CFD preprocessor and the mesh is divided. Then the CFD solver is used to calculate the water production of the model. Finally, the CFD post processor is used to present the calculation results in an image. On this basis, this paper has carried out a large number of experimental analysis. In the analysis process, this paper compares the calculation results of the solver with the actual operating system results of MBR. The comparison results show that the calculation results of the solver are basically consistent with the actual water production of membrane modules, and have higher calculation accuracy. It achieves the purpose of accurately calculating the water production of membrane modules, and solves the problem of measuring the working efficiency of MBR system by calculating the water production of membrane modules. which has certain reference value for MBR engineering design and research.

In the Membrane Bio-Reactor waste-water treatment system,The water production of membrane modules is an important parameter to measure the working efficiency of MBR system, while the internal pressure series MBR is a common membrane module connection method. Therefore, the calculation and analysis of the water production of internal pressure series MBR system by computational fluid dynamics is carried out. In the analysis process, the geometric model of the internal pressure series MBR system is first established by the CFD preprocessor and the mesh is divided. Then the CFD solver is used to calculate the water production of the model. Finally, the CFD post processor is used to present the calculation results in an image. On this basis, this paper has carried out a large number of experimental analysis. In the analysis process, this paper compares the calculation results of the solver with the actual operating system results of MBR. The comparison results show that the calculation results of the solver are basically consistent with the actual water production of membrane modules, and have higher calculation accuracy. It achieves the purpose of accurately calculating the water production of membrane modules, and solves the problem of measuring the working efficiency of MBR system by calculating the water production of membrane modules. which has certain reference value for MBR engineering design and research.

In the Membrane Bio-Reactor waste-water treatment system,The water production of membrane modules is an important parameter to measure the working efficiency of MBR system, while the internal pressure series MBR is a common membrane module connection method. Therefore, the calculation and analysis of the water production of internal pressure series MBR system by computational fluid dynamics is carried out. In the analysis process, the geometric model of the internal pressure series MBR system is first established by the CFD preprocessor and the mesh is divided. Then the CFD solver is used to calculate the water production of the model. Finally, the CFD post processor is used to present the calculation results in an image. On this basis, this paper has carried out a large number of experimental analysis. In the analysis process, this paper compares the calculation results of the solver with the actual operating system results of MBR. The comparison results show that the calculation results of the solver are basically consistent with the actual water production of membrane modules, and have higher calculation accuracy. It achieves the purpose of accurately calculating the water production of membrane modules, and solves the problem of measuring the working efficiency of MBR system by calculating the water production of membrane modules. which has certain reference value for MBR engineering design and research.

The focus of research in the computational fluid dynamics (CFD) area is two fold: (1) to develop new approaches for turbulence modeling so that high speed compressible flows can be studied for applications to entry and re-entry flows; and (2) to perform research to improve CFD algorithm accuracy and efficiency for high speed flows. Research activities, faculty and student participation, publications, and financial information are outlined.

The focus of research in the computational fluid dynamics (CFD) area is two fold: (1) to develop new approaches for turbulence modeling so that high speed compressible flows can be studied for applications to entry and re-entry flows; and (2) to perform research to improve CFD algorithm accuracy and efficiency for high speed flows. Research activities, faculty and student participation, publications, and financial information are outlined.

The focus of research in the computational fluid dynamics (CFD) area is two fold: (1) to develop new approaches for turbulence modeling so that high speed compressible flows can be studied for applications to entry and re-entry flows; and (2) to perform research to improve CFD algorithm accuracy and efficiency for high speed flows. Research activities, faculty and student participation, publications, and financial information are outlined.

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.