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Research Interests: Engineering, Physics, Numerical Simulation, Mathematical Sciences, Mathematical Analysis, and 15 morePhysical sciences, Nonlinear Stability, Second Order, Linear Stability, Nonlinear system, Differential equation, Compressible Flow, Initial Condition, Amplitude, Mixed layer, Ordinary Differential Equation, Mach Number, Exponential Decay, nonlinear equation, and Nonlinear Effect
The goal of this project is to investigate the dynamics of multiple interacting high speed jets. To this end, a parallel three-dimensional direct simulation Monte Carlo (DSMC) code is developed. An iterative flux method is used to... more
The goal of this project is to investigate the dynamics of multiple interacting high speed jets. To this end, a parallel three-dimensional direct simulation Monte Carlo (DSMC) code is developed. An iterative flux method is used to implement the pressure boundary conditions in DSMC. Jets expanding into a vacuum and into a specified pressure background are investigated, as is the influence of the background gas on the interacting jets. Empirical models will be developed. In the past year, the code has been successfully parallelized and executed in Seawulf Cluster, using domain decomposition with the MPI protocol. Code validation is in progress, for which a one-dimensional shock tube problem with Mach number up to 10 has been investigated. Preliminary results for three-dimensional interacting jets have also been obtained using the parallel code.
The goal envisioned for the Reduced-Order Computational Fluid Dynamics and Heat Transfer (ROM-CFDHT) procedure is obtaining fast turnaround in simulation time so that computational fluid dynamics c...
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This paper has the objective of addressing a few basic issues pertaining to the use of the laminar flamelet method to model turbulence-combustion interactions in supersonic combustion. Specifically...
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Although hydrogen has the desired ignition properties for supersonic combustion in a scramjet, it has the disadvantage of low energy density, thereby motivating the interest in alternate, mostly hy...
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An overview of recent efforts at developing a high-fidelity simulation tool for dynamic weakly ionized plasma phenomena is presented in this paper. The work also has an experimental component intended to provide extensive validation data.... more
An overview of recent efforts at developing a high-fidelity simulation tool for dynamic weakly ionized plasma phenomena is presented in this paper. The work also has an experimental component intended to provide extensive validation data. The various models investigated are physics-based, and are cast in a form that was incorporated into AEROFLO, which is a high fidelity CFD software tool developed by TTC Technologies, Inc. As a first step, magnetohydrodynamic (MHD) models were validated with experimental data obtained at the Ohio State University (OSU). The implementation of a generalized boundary condition framework for the MHD variables, conductivity, electric potential and the field variables is described. The procedure allows easy specification of boundary conditions. The feasibility of implementing the additional transport equations that are needed to describe thermal nonequilibrium, air chemistry, and plasma dynamics in AEROFLO are described. The experimental program also produced reduced kinetic models for the air chemistry, quantified the rapid energy thermalization phenomena, and measured the temperature rise due to repetitive nanosecond pulse discharge. The results of the experiments provide insight into the mechanism of flow control by nanosecond pulse, low-temperature plasma, as well as key nsec plasma actuator characterization and scaling data for validation of flow codes used for predictive modeling of high-speed flow control.
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This paper compares empirical and computational fluid dynamics (CFD) based exergy calculation procedures for modeling the airframe subsystem of aircraft. Calculations were based on the B747-200 aircraft, with the presumption that the... more
This paper compares empirical and computational fluid dynamics (CFD) based exergy calculation procedures for modeling the airframe subsystem of aircraft. Calculations were based on the B747-200 aircraft, with the presumption that the empirical methods were valid. They were carried out for a range of values of the angle of attack, assuming transonic flight. Good agreement was observed for one approach, supporting the viability of using CFD for realistic airframe calculations in a system-level analysis and design optimization.
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Dual-mode scramjets, which are the systems of primary interest in this study, have intricate dynamics, including complex and unsteady pseudo-shock phenomenon, thermal choking, and the potential performance issue of unstart, that need to... more
Dual-mode scramjets, which are the systems of primary interest in this study, have intricate dynamics, including complex and unsteady pseudo-shock phenomenon, thermal choking, and the potential performance issue of unstart, that need to be thoroughly understood in order to design realistic air-breathing hypersonic vehicles. Our interest focuses on the manner in which pressure is treated within the laminar flamelet framework to modeling turbulence-combustion interaction. The laminar flamelet method provides a highly efficient means of modeling combustion when the mass fractions of a large number of species are of interest. However, the original approach was developed for combustion in low-speed flows. Extension to high-speed flows has been done in several ways in our work, including the addition of pressure as an independent variable of the flamelet library and using several formulations for this. To further improve model fidelity, several progress variable interpolations from the S-...