bono wasistho

University of Illinois at Urbana-Champaign, CSAR, Post-Doc

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Papers by bono wasistho

4. Title and Subtitle

Public reporting burden for this collection of information is estimated to average 1 hour per res... more Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection o information including sugg^ons to reduang

DNS of Subsonic Spatially Developing Shear Flows

Fluid Mechanics and Its Applications, 1998

We perform direct numerical simulations (DNS) of transition in shear flows. The adequacy of the n... more We perform direct numerical simulations (DNS) of transition in shear flows. The adequacy of the numerical method used is first validated in the linear regime of flow perturbations. In particular we consider a comparison study between DNS and the Linear Stability Theory (LST) in a spatially developing compressible mixing layer in two dimensions. The method is subsequently applied to a simulation of separation bubble induced transition in three dimensions. We use a fourth order central scheme for the spatial dicretization and four-stage second order Runge-Kutta for the time integration. The boundary conditions along the artificial boundaries are based on the non-reflecting characteristic method. A periodic boundary condition is employed in the spanwise direction. In addition, we apply a direct method of buffer domain technique to damp wave reflections at the outflow boundary. The description of the numerical method, the boundary conditions and the buffer domain technique can be found in [7].

On Steady and Unsteady Shock Boundary-Layer Interactions Under Suction and Blowing

Spatial Direct Numerical Simulation of Compressible Boundary Layer flow

ter verkrijging van de graad van doctor aan de Universiteit Twente, op gezag van de rector magnic... more

Large-Eddy Simulation of the mutual induction dynamics of double helical vortices

Direct and Large Eddy Simulations of Compressible Wall Injection Flows in Laminar, Transition and Turbulent Regimes

38th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2002

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Full-Physics Large-Scale Multiphase Large Eddy Simulations of Flow Inside Solid Rocket Motors

38th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2002

Effects of Aluminum Propellant Loading and Size Distribution in BATES Motors: A Multiphysics Computational Analysis

41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2005

Flow modeling and simulation of solid-propellant rocket motors from rst principles are quite chal... more Flow modeling and simulation of solid-propellant rocket motors from rst principles are quite challenging due to complex evolving geometries, turbulence, and multi-phase o w with chemically reactive disperse phase. A exible computational framework has been developed where multiphase o w computations are performed that include three-way conservative coupling between the phases (mixture-droplet-smoke), a stochastic droplet injection, and full heat release for the burning mechanism. Results obtained from computations with burning aluminum droplets generating aluminum-oxide smoke are described for the 15-lb BATES test motor. The eects of injected droplet size distribution and aluminum loadings in the propellant are investigated and show the eect on the chamber o w dynamics, primarily at the nozzle inlet and the droplet combustion eciency . It is seen that droplets with diameter less than 100m are fully consumed by the time they reach the nozzle. Results obtained from simple theoretical models provide a map of the residence time, droplet combustion eciency and nal diameter for various initial diameters and streamwise locations.

Effect of Turbulence and Particle Combustion on Solid Rocket Motor Instabilities

41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2005

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Full 3-D Simulation of Turbulent Flow in the RSRM

42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2006

We compute turbulent internal flows in large solid rocket motors on meshes with unprecedented spa... more We compute turbulent internal flows in large solid rocket motors on meshes with unprecedented spatial resolution using the Rocstar3 package developed at CSAR. Since turbulent flow fields in firing rockets are difficult to measure in great detail, we use a highresolution numerical simulation of the TitanIV SRMU PQM-1 booster for validation of the Large Eddy Simulation (LES) turbulence models applied to these geometries. Aft of the star grain region, the flow is fully turbulent under quasi-steady operating conditions, and the LES model with eddy-viscosity-type subgrid scale model proves to be reasonably accurate even on rather coarse grids. Analysis of the thermal pressure history in the Titan and the Space Shuttle Reusable Solid Rocket Motor (RSRM) at various stations reveals highfrequency (several hundred Hz) pressure oscillations of locally significant amplitude, which are due to vortex shedding near joint slots. Such oscillations have not been predicted in earlier simulations, but can excite certain acoustic and structural vibration modes.

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Compressible Wall-Injection Flows in Laminar, Transitional, and Turbulent Regimes: Numerical Prediction

Journal of Spacecraft and Rockets, 2004

Numerical simulations of compressible rocket flows are conducted in laminar, transitional, and tu... more Numerical simulations of compressible rocket flows are conducted in laminar, transitional, and turbulent regimes. The laminar simulation is carried out on a planar rocket flow without nozzle using the unsteady two-dimensional Navier-Stokes system. The transitional and turbulent flows are performed in three-dimensional on an extended rocket geometry with a divergent outlet using compressible large eddy simulation (LES) models. In both cases, the compressibility effect plays an important role. In the laminar case, pressure oscillation is forced at the outflow boundary. The time-averaged part of the solution is compared with the inviscid theory of compressible rocket flow of Balakrishnan et al.

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Simulation techniques for spatially evolving instabilities in compressible flow over a flat plate

Computers & Fluids, 1997

In this paper we present numerical techniques suitable for a direct numerical simulation in the s... more In this paper we present numerical techniques suitable for a direct numerical simulation in the spatial setting. We demonstrate the application to the simulation of compressible flat plate flow instabilities. We compare second and fourth order accurate spatial discretization schemes in combination with explicit multistage time stepping for the simulation of the 2D Navier-Stokes equations. We consider Mach numbers 0.5 and 4.5. In the vicinity of the outflow boundary, an efficient buffer domain treatment is introduced, which is suitable in conjunction with an explicit time integration scheme. This treatment requires only a short buffer domain to damp wave reflections at the outflow boundary. Results for the instability of Tollmien-Schlichting (T-S) waves are compared with two instability theories, linear stability theory (LST) and linear parabolized stability equations (PSE). The growth rates of T-S waves for parallel base flow at both Mach numbeis compare well with LST results. Moreover, the growth rates of T-S waves for nonparallel base flow compare well with results obtained by solving the PSE at Mach number 0.5. The second order discretization scheme requires, however, considerably higher grid resolution than the fourth order method to achieve accurate results. High amplitude disturbances were also considered to activate nonlinear terms. The nonlinearity strongly affects the form of the T-S waves and the growth rate of the disturbance:. The results obtained here support the use of these numerical techniques in flow simulations with increasing complexity such as flat plate flow simulations up to the turbulent regime and with separation regions in 3D. The results also encourage the use of perturbations derived from the compressible PSE as inlet perturbations for nonparallel flow.

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A Coherent vorticity preserving eddy-viscosity correction for Large-Eddy Simulation

Journal of Computational Physics

This paper introduces a new approach to Large-Eddy Simulation (LES) where subgrid-scale (SGS) dis... more This paper introduces a new approach to Large-Eddy Simulation (LES) where subgrid-scale (SGS) dissipation is applied proportionally to the degree of local spectral broadening, hence mitigated or deactivated in regions dominated by large-scale and/or laminar vortical motion. The proposed coherentvorticity preserving (CvP) LES methodology is based on the evaluation of the ratio of the test-filtered to resolved (or grid-filtered) enstrophy, σ. Values of σ close to 1 indicate low sub-test-filter turbulent activity, justifying local deactivation of the SGS dissipation. The intensity of the SGS dissipation is progressively increased for σ < 1 which corresponds to a small-scale spectral broadening. The SGS dissipation is then fully activated in developed turbulence characterized by σ ≤ σ eq , where the value σ eq is derived assuming a Kolmogorov spectrum. The proposed approach can be applied to any eddy-viscosity model, is algorithmically simple and computationally inexpensive. LES of Taylor-Green vortex breakdown demonstrates that the CvP methodology improves the performance of traditional, non-dynamic dissipative SGS models, capturing the peak of total turbulent kinetic energy dissipation during transition. Similar accuracy is obtained by adopting Germano's dynamic procedure albeit at more than twice the computational overhead. A CvP-LES of a pair of unstable periodic helical vortices is shown to predict accurately the experimentally observed growth rate using coarse resolutions. The ability of the CvP methodology to dynamically sort the coherent, large-scale motion from the smaller, broadband scales during transition is demonstrated via flow visualizations. Finally, the CvP methodology is also shown to improve the accuracy of subrid models in LES of compressible turbulent channel flow.

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Very-high-Reynolds-number vortex dynamics via Coherent-vorticity-Preserving (CvP) Large-eddy simulations

Bulletin of the American Physical Society, 2017

Rocturb User's Guide

Numerical Investigation of the Separated Flow Over a Smoothly Contoured Ramp

Large Eddy Simulation (LES) and ReynoldsaveragedNavier-Stokes(RANS)calculationshave been used to ... more Large Eddy Simulation (LES) and ReynoldsaveragedNavier-Stokes(RANS)calculationshave been used to predict the development, separation, reattachmentand downstreamrecovery of the flow over a smoothlycontouredramp. The statisticallytwo-dimensionalupstreamflow separatesalong the ramp surfaceand then reattaches downstreamon a flat section. A canonicalflatplate turbulent boundary layer at a momentum thicknessReynolds number1100, and having a boundarylayer thickness , is introduced four ramplengthsupstreamof theonsetof curvature. Subgrid-scale(SGS)stressesin theLES are closedusingthedynamiceddyviscositymodelof Germanoet al. (1991). RANS calculationsof the steady-statesolutionareperformedusingtwo leading models: Spalart-Allmaras(Spalart-Allmaras 1994) and (Durbin 1991). Mean flow predictionsobtainedusingall the modelsagreewell with theexperimentalmeasurements of Songet al. (2000). Boundarylayer detachment occursalong the curved section( ) with reattachmentat roughly . Theprimary turbulent sh...

Large Eddy Simulation of Multi Phase Flow inside Solid Rocket Chamber

ABSTRACT

Prediction of the separated flow around forebody cross-sections

ABSTRACT

Taxes and labor supply of high-income physicians

Journal of Public Economics, 1997

We use the 19831985 Physicians' Practice Costs and Income Survey, supplemented with federal... more

Development of adaptive subgrid scale models based on a large-scale vorticity sensor

4. Title and Subtitle

DNS of Subsonic Spatially Developing Shear Flows

Fluid Mechanics and Its Applications, 1998

On Steady and Unsteady Shock Boundary-Layer Interactions Under Suction and Blowing

Spatial Direct Numerical Simulation of Compressible Boundary Layer flow

ter verkrijging van de graad van doctor aan de Universiteit Twente, op gezag van de rector magnic... more

Large-Eddy Simulation of the mutual induction dynamics of double helical vortices

Direct and Large Eddy Simulations of Compressible Wall Injection Flows in Laminar, Transition and Turbulent Regimes

38th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2002

Download

Full-Physics Large-Scale Multiphase Large Eddy Simulations of Flow Inside Solid Rocket Motors

38th AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2002

Effects of Aluminum Propellant Loading and Size Distribution in BATES Motors: A Multiphysics Computational Analysis

41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2005

Effect of Turbulence and Particle Combustion on Solid Rocket Motor Instabilities

41st AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2005

Download

Full 3-D Simulation of Turbulent Flow in the RSRM

42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2006

Download

Compressible Wall-Injection Flows in Laminar, Transitional, and Turbulent Regimes: Numerical Prediction

Journal of Spacecraft and Rockets, 2004

Download

Simulation techniques for spatially evolving instabilities in compressible flow over a flat plate

Computers & Fluids, 1997

Download

A Coherent vorticity preserving eddy-viscosity correction for Large-Eddy Simulation

Journal of Computational Physics

Download

Very-high-Reynolds-number vortex dynamics via Coherent-vorticity-Preserving (CvP) Large-eddy simulations

Bulletin of the American Physical Society, 2017

Rocturb User's Guide

Numerical Investigation of the Separated Flow Over a Smoothly Contoured Ramp

Large Eddy Simulation of Multi Phase Flow inside Solid Rocket Chamber

ABSTRACT

Prediction of the separated flow around forebody cross-sections

ABSTRACT

Taxes and labor supply of high-income physicians

Journal of Public Economics, 1997

We use the 19831985 Physicians' Practice Costs and Income Survey, supplemented with federal... more

Development of adaptive subgrid scale models based on a large-scale vorticity sensor

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