WorldCat Identities

Sahu, Jabaraj

Overview
Works: 59 works in 78 publications in 1 language and 1,449 library holdings
Roles: Author
Classifications: TL574.T8,
Publication Timeline
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Most widely held works by Jabaraj Sahu
Navier-Stokes computational study of axisymmetric transonic turbulent flows with a two-equation model of turbulence by Jabaraj Sahu( )

1 edition published in 1984 in English and held by 3 WorldCat member libraries worldwide

A thin-layer Navier-Stokes code has been used to compute the turbulent flow over two axisymmetric bodies at transonic speeds and the results are compared to experiment. A critical element of calculating such flows is the turbulence model. Numerical computations have been made with an algebraic eddy viscosity model and the k-epsilon two-equation model. The k-epsilon equations are developed in a general spatial coordinate system and incorporated into the thin-layer, compressible, time dependent Navier-Stokes code. The same implicit algorithm that simultaneously solves the Reynolds-averaged mean flow equations is extended to solve the turbulence field equations using block tridiagonal matrix inversions. Calculations with the k-epsilon model are extended up to the wall and exact values of k and epsilon at the wall are used as boundary conditions
Comparison of Numerical Flow Field Predictions for Army Airdrop Systems( Book )

3 editions published in 1999 in English and held by 1 WorldCat member library worldwide

A computational study has been performed to determine the aerodynamics of Army airdrop systems using computational fluid dynamics (CFD). The validation of flow field predictions from CFD software packages for airdrop systems is difficult because comprehensive experimentally obtained data are lacking. This is especially true for real systems because obtaining desired flow field data during a test is not practical or possible with available technologies. This report examines the results of predictions from two separate CFD codes for the same airdrop systems as an initial step toward validating high performance computing software for modeling airdrop systems. Numerical results have been obtained on two airdrop systems used by the U.S. Army: the T-10 personnel system (no payload) and the G-12 cargo system with and without a payload. The two software packages used for the comparisons are a CFD code that employs a stabilized semi-discrete finite element formulation of the incompressible Navier-Stokes equations and CFD++, a commercially available code. For this numerical experiment, computed unsteady flow fields were obtained with the same unstructured mesh, and predicted flow fields were compared. Similarities and discrepancies in the comparisons are highlighted, and conclusions are drawn from these results
Parallel Numerical Computations of Projectile Flow Fields( Book )

2 editions published in 1999 in English and held by 1 WorldCat member library worldwide

A time-marching, Navier-Stokes code, successfully used over a decade for projectile aerodynamics, was chosen as a test case and optimized to run on modern reduced instruction set computer (RISC)-based parallel computers. The parallelized version of the code has been used to compute the axisymmetric and three-dimensional (3-D) turbulent flow over a number of projectile configurations at transonic and supersonic speeds. In most of these cases, these results were then compared to those obtained with the original version of the code on a Cray C-90. Both versions of the code produced the same qualitative and quantitative results. Considerable performance gain was achieved by the optimization of the serial code on a single processor. Parallelization of the optimized serial code, which uses loop-level parallelism, led to additional gains in performance. The original algorithm remained unchanged. Recent runs on a 128-processor Origin 2000 have produced speedups in the range of 1026 over that achieved when using a single processor on a Cray C-90. The original algorithm remained unchanged. Computed surface pressures were compared with the experimental data and were generally found to be in good agreement with the data
Application of CFD to High Angle of Attack Missile Flow Fields( Book )

2 editions published in 2000 in English and held by 1 WorldCat member library worldwide

Computational fluid dynamics (CFD) calculations have been performed for a missile body with and without fins. Numerical flow field computations have been made for various Mach numbers and roll angles using an unsteady zonal Navier-Stokes code (ZNSFLOW) and the chimera composite grid discretization technique at supersonic velocity and high angle of attack. Steady-state numerical results have been obtained and compared for cases modeling an ogive-cylinder missile with and without fins. Computed results show the details of the expected flow field features to include vortical crossflow separation. Computed results are compared with experimental data obtained for the same configurations and conditions and are generally found to be in good agreement with the data. The results help to show the predictive capabilities of CFD techniques for supersonic projectiles at incidence
Using computational fluid dynamics-rigid body dynamic (CFD-RBD) results to generate aerodynamic models for projectile flight simulation by Mark Costello( Book )

2 editions published in 2007 in English and held by 1 WorldCat member library worldwide

"A method to efficiently generate a complete aerodynamic description for projectile flight dynamic modeling is described. At the core of the method is an unsteady, time-accurate computational fluid dynamics simulation that is tightly coupled to a rigid projectile flight dynamic simulation. A set of short time snippets of simulated projectile motion at different Mach numbers is computed and employed as baseline data. For each time snippet, aerodynamic forces and moments and the full rigid body state vector of the projectile are known. With time-synchronized air loads and state vector information, aerodynamic coefficients can be estimated with a simple fitting procedure. By inspecting the condition number of the fitting matrix, we can assess the suitability of the time history data to predict a selected set of aerodynamic coefficients. The technique is exercised on an exemplar fin-stabilized projectile with good results."--Report documentation page
3-D Parachute Descent Analysis Using Coupled Computational Fluid Dynamic and Structural Codes( Book )

2 editions published in 1997 in English and held by 1 WorldCat member library worldwide

A computational tool that models the terminal descent characteristics of a single or a cluster of parachutes is a technology that is needed by parachute designers and engineers. As part of a technology program annex (TPA), a joint effort between the U.S. Army Natick Research, Development, and Engineering Center (NRDEC) and the U.S. Army Research Laboratory (ARL) to develop this computational tool is now under way. As a first effort, attempts are being made to analyze both two-dimensional (2- D) and three-dimensional (3-D) flow fields around a parachute using a coupling procedure in which the fluid dynamics are coupled to 2-D and 3-D structural dynamic (SD) codes. This effort uses computational fluid dynamic (CFD) codes to calculate a pressure field, which is then used as an input load for the SD code. Specifically, this report presents the methods and results of the flow field plus the structural characteristics of a single axisymmetric parachute and a 3-D gore configuration for the terminal descent velocity. Computed results have been obtained using the payload weight and unstretched constructed geometry of the canopies as input. Significant progress has been made in determining the terminal descent flow field along with the terminal shape of the parachute. A discussion of the fluid and structural dynamics codes, coupling procedure, and the associated technical difficulties is presented. Examples of the codes' current capabilities are shown
Computational Modeling of a Segmented Projectile( Book )

2 editions published in 1999 in English and held by 1 WorldCat member library worldwide

This report describes the application of the chimera numerical technique to a multi-body segmented projectile configuration system of interest to the U.S. Army. Computations were performed at a supersonic speed on this configuration which consists of an ogive cylinder projectile with a peg shaped trailing segment. The computed results show the qualitative features of the wake flow field for the projectile with the segment in three different positions: centered, offset, and angled. The segment in the offset position has a strong effect on the flow field in the aft region of the projectile, thus affecting the aerodynamic coefficients of the projectile. The force and moment coefficients of the segment are also significantly affected by the orientation of the segment
Computational Fluid Dynamics Modeling of Parachute Clusters( Book )

2 editions published in 1997 in English and held by 1 WorldCat member library worldwide

A computational tool that models the terminal descent characteristics of a single or a cluster of parachutes is a technology that is needed by parachute designers and engineers. As part of a technology program annex (TPA), a joint effort between the U.S. Army Natick Research, Development, and Engineering Center (RRDEC) and the U.S. Army Research Laboratory (ARL) to develop this computational tool is now under way. As a first effort, attempts are being made to analyze both two-dimensional (2- D) and three-dimensional (3-D) flow fields around a parachute using a coupling procedure in which the fluid dynamics are coupled to 2-D and 3-D structural dynamic (SD) codes. This effort uses computational fluid dynamic (CFD) codes to calculate a pressure field, which is then used as an input load for the SD code. Specifically, this report presents the methods and results of the flow field plus the structural characteristics of a single axisymmetric parachute and a 3-D gore configuration for the terminal descent velocity. Computed results have been obtained using the payload weight and unstretched constructed geometry of the canopies as input. Significant progress has been made in determining the terminal descent flow field along with the terminal shape of the parachute. A discussion of the fluid and structural dynamics codes, coupling procedure, and the associated technical difficulties is presented. Examples of the codes' current capabilities are shown
Numerical Computations of Supersonic Flow Over Elliptical Projectiles( Book )

2 editions published in 2001 in English and held by 1 WorldCat member library worldwide

Computational fluid dynamics (CFD) approaches were used to compute the supersonic and hypersonic flow fields and aerodynamic forces and moments on elliptical projectiles. Steady state numerical results have been obtained at several supersonic Mach numbers between 2.5 and 4.0 and several angles of attack from 0 to 12 degrees for the 'jet-off' conditions with the use of Euler and Navier-Stokes flow solvers. In addition, numerical computations have been performed for the 'jet-on' conditions to study the interaction of a helium jet with a free stream Mach 4.0 flow. In general, very good agreement of the computed aerodynamic coefficients with the experimental data was achieved at all speeds and angles of attack investigated for jet-off conditions. A small discrepancy exists in the comparisons for the axial force. CFD results for the jet-on case show the qualitative features and strong flow interaction between the jet and the free stream flow. The results show the predictive capabilities of CFD techniques for supersonic flow over elliptical projectiles
Computational Fluid Dynamics Modeling of Multi-body Missile Aerodynamic Interference( Book )

2 editions published in 1998 in English and held by 1 WorldCat member library worldwide

Computational fluid dynamics (CFD) calculations have been performed for a multi-body system consisting of a main missile and a number of submunitions. Numerical flow field computations have been made for various orientations and locations of submunitions using an unsteady, zonal Navier-Stokes code and the chimera composite grid discretization technique at transonic speeds and zero degree angle of attack. Both steady state and unsteady numerical results have been obtained and compared for two submunitions and a missile system. Computed results show the details of the expected flow field features, including the shock interactions. Computed results are compared with limited experimental data obtained for the same configuration and conditions and are generally found to be in good agreement with the data. Comparison of the unsteady and steady state results shows an appreciable change in the aerodynamic forces and moments
Computational Modeling of Sense and Destroy Armor (SADARM) Submunition Separation/Collision( Book )

2 editions published in 1997 in English and held by 1 WorldCat member library worldwide

Sense and Destroy Armor (SADARM) is a high-priority Army program that experienced an initial design flaw, leading to submunition collisions. Computational fluid dynamics (CFD), including Chimera overset technology, has recently been applied to solve this problem. The CFD modeling has provided significant physical insight into the complex unsteady flow field associated with the SADARM submunitions during the separation/ejection process. CFD simulations have predicted that, with the addition of the fins on the trailing submunition, separation will occur, and collisions will be avoided
Unsteady Numerical Simulations of Subsonic Flow Over a Projectile with Jet Interaction by Jabaraj Sahu( Book )

3 editions published in 2003 in English and held by 1 WorldCat member library worldwide

This report describes a computational study undertaken to consider the aerodynamic effect of synthetic jets as a means to provide the control authority needed to maneuver a projectile at low subsonic speeds. The time-accurate Navier-Stokes computational technique has been used to obtain numerical solutions for the unsteady jet interaction flow field for a projectile at a subsonic speed, Mach = 0.11, and several angles of attack from O deg to 4 deg. Qualitative flow field features show the interaction of the time dependent jet with the free stream flow. Numerical results show the effect of the jet on the flow field, surface pressures and aerodynamic coefficients. Unsteady numerical results have been obtained for a two-dimensional jet flow and compared with experimental data for validation. The same unsteady jet modeling technique has been applied to a subsonic projectile. These numerical results are being assessed to determine if synthetic jets can be used to provide the control authority needed for maneuvering munitions to hit the targets with precision
Numerical Simulations of Supersonic Flow Over an Elliptic Projectile with Jet Interaction by Jabaraj Sahu( Book )

3 editions published in 2003 in English and held by 1 WorldCat member library worldwide

Computational fluid dynamics (CFD) approaches were used to compute the supersonic flow fields and aerodynamic forces and moments on an elliptic projectile with jet interaction. Steady state numerical results have been obtained for the jet interaction problem at a supersonic Mach number, Mach = 4.0, and several angles of attack from 0 deg to 12 deg via Navier-Stokes computational techniques. The jet modeled in this problem is a supersonic helium jet exhausted into the free stream flow at a high pressure. Computed CFD results show the qualitative features and strong flow interaction between the jet and the free-stream flow. In general, very good agreement of the computed aerodynamic coefficients with the experimental data was achieved for all angles of attack investigated for the "jet-on" conditions. The results show the predictive capabilities of CFD techniques for supersonic flow over elliptic projectiles with jet interaction
Computational Fluid Dynamics Modeling of a 40-mm Grenade with and Without Jet Flow( Book )

2 editions published in 2001 in English and held by 1 WorldCat member library worldwide

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
Numerical computations of supersonic flow over a square cross-section missile by Sidra I Silton( )

1 edition published in 2005 in English and held by 0 WorldCat member libraries worldwide

This report describes a computational study undertaken to determine the aerodynamics of a nonaxisymmetric missile with a square cross section. Numerical solutions have been obtained at supersonic speeds for various roll orientations and angles of attack using a two-equation Reynolds-averaged Navier-Stokes turbulence model. Numerical results show the qualitative features (vortices and cross-flow separation regions) of the flow field at various stream wise positions along the missile configurations. Aerodynamic coefficients have been obtained from the computed solutions and found to match well with the available experimental data for these configurations. These numerical results show the ability of computational fluid dynamics techniques to accurately predict the aerodynamics of nonaxisymmetric missiles with a square cross section
Time-accurate numerical prediction of free flight aerodynamics of a finned projectile by Jabaraj Sahu( )

1 edition published in 2005 in English and held by 0 WorldCat member libraries worldwide

This report describes a new multi-disciplinary computational study undertaken to compute the flight trajectories and to simultaneously predict the unsteady free flight aerodynamics of a finned projectile configuration. Actual flight trajectories are computed by an advanced coupled computational fluid dynamics (CFD)-rigid body dynamics technique. An advanced time-accurate Navier-Stokes computational technique has been used in CFD to compute the unsteady aerodynamics associated with the free flight of the finned projectile at supersonic speeds. Computed positions and orientations of the projectile have been compared with actual data measured from free flight tests and are found to be generally in good agreement. Predicted aerodynamics forces and moments also compare well with the forces and moments used in the six-degree-of freedom fits of the results of the same tests. Unsteady numerical results obtained from the coupled method show the aerodynamic forces and moments and the flight path of the projectile
Application of Computational Fluid Dynamics to a Monoplane Fixed-Wing Missile With Elliptic Cross Sections by Karen R Heavey( )

2 editions published in 2005 in English and held by 0 WorldCat member libraries worldwide

This report describes a computational study undertaken to investigate the performance of the CFD++ flow solver for prediction of nonlinear aerodynamics of a complex finned missile using structured hexahedral and unstructured tetrahedral grids. A monoplane fixed-wing missile with elliptic cross sections provided a geometrically complex model. Numerical solutions were obtained for this configuration at supersonic speed for various roll orientations, angles of attack, and jaw angles. Steady-state solutions were obtained using a three-dimensional Reynolds-Averaged Navier-Stokes solver with a two-equation turbulence model. Numerical results show the qualitative features of the flow fields at various cross-sectional and streamwise positions along the computational model of the missile. Aerodynamic coefficients were extracted from the computed solutions and found to match well with the available experimental data for these configurations. These numerical results show the effectiveness of using computational fluid dynamics techniques to produce an accurate prediction of the aerodynamics of geometrically complete configurations
Time-accurate simulations of synthetic jet-based flow control for an axisymmetric spinning body by Jabaraj Sahu( )

1 edition published in 2004 in English and held by 0 WorldCat member libraries worldwide

This report describes a computational study undertaken to consider the aerodynamic effect of synthetic jets as a means of providing the control authority needed to maneuver a projectile at a low subsonic speed. A time-accurate Navier-Stokes computational technique has been used to obtain numerical solutions for the unsteady jet-interaction flow field for a spinning projectile at a subsonic speed, Mach 0.24, and angle of attack, 0 degree. Numerical solutions have been obtained by Reynolds-averaged Navier-Stokes (RANS) and hybrid RANS-large-eddy simulation turbulence models. Unsteady numerical results show the effect of the jet on the flow field and the aerodynamic coefficients, particularly the lift force. These numerical results are being used to assess if synthetic jets can be used to provide the control authority needed for maneuvering munitions to hit the targets with precision
Computational Fluid Dynamics Modeling of Submunition Separation from Missile by Harris L Edge( )

2 editions published in 1999 in English and held by 0 WorldCat member libraries worldwide

Computational fluid dynamics calculations have been performed for a multi-body system consisting of a main missile and a number of submunitions. Numerical flow field computations have been made for various orientations and locations of submunitions using an unsteady, zonal Navier-Stokes code and the chimera composite grid discretization technique at low supersonic speeds and 0 deg angle of attack. Steady state numerical results have been obtained and compared for cases modeling six submunitions in pitch-plane symmetry and ten submunitions for which symmetry could not be exploited. Computed results show the details of the expected flow field features including the shock interactions. Computed results are compared with limited experimental data obtained for the same configuration and conditions and are generally found to be in good agreement with the data. The results help to quantify changes in the aerodynamic forces and moments, which are attributable to changes in position of the submunitions relative to one another
Time-accurate computations of free-flight aerodynamics of a spinning projectile with and without flow control by Jabaraj Sahu( )

2 editions published in 2006 in English and held by 0 WorldCat member libraries worldwide

This report describes a new multi-disciplinary computational study undertaken to compute the flight trajectories and simultaneously predict the unsteady free flight aerodynamics of a spinning projectile configuration with and without aerodynamic flow control. Actual flight trajectories are computed with an advanced coupled computational fluid dynamics (CFD)-rigid body dynamics (RBD) technique. An advanced time-accurate Navier-Stokes computational technique has been used in CFD to compute the unsteady aerodynamics associated with the free flight of the spinning projectile at subsonic speeds. Computed positions and orientations of the projectile have been compared with actual data measured from free flight tests and are found to be generally in good agreement. The same advanced coupled procedure has been used to compute the aerodynamics of the spinning projectile with flow control with the use of a synthetic microjet. Unsteady numerical results obtained from the coupled method show the flow field, the aerodynamic forces and moments, and the flight trajectories of the projectile
 
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Alternative Names
Sahu, Jubaraj

Languages
English (39)