Shankar Ghosh

Viscous effects on high enthalpy flow over a double-wedge are studied using computational fluid dynamics (CFD). Local thermodynamic equilibrium (LTE) conditions are assumed to apply. A finite volume based compressible flow solver is developed for the purpose. Effects of LTE based properties of air on the resulting flow field are studied in detail.

A hybrid RANS/LES framework is proposed to simulate a zero pressure gradient supersonic turbulent boundary layer over a flat plate. A delayed detached eddy simulation (DDES) framework is used. A non-zonal approach is used to transition between a SST k − ω RANS model and a compressible dynamic Smagorinsky model. A finite volume based flow solver using a sixth-order compact interpolation method is developed for the purpose. The numerical method is validated using a Mach 2 zero pressure gradient flat plate turbulent boundary layer simulation.

Nonequilibrium effects on hypersonic canonical shock/turbulence interaction are studied using DNS. A hybrid higher order finite difference based flow solver is developed for the purpose. Nonequilibrium processes like vibrational excitation and chemical reactions are incorporated. Simulations are performed to study the individual and combined effects of these nonequilibrium processes. Nonequilibrium effects on both the mean flow and the turbulence are investigated.

The effects of pulsed energy deposition in an inviscid supersonic flow over a cylinder is studied using numerical simulation. A finite volume based flow solver is developed using the AUSMDV scheme. Interaction of the energy deposition core and the associated blast wave with the cylinder and its bow shock is studied. The resulting reduction in drag is computed and the optimum frequency of energy deposition for maximum drag reduction is investigated.

A finite volume based method for large eddy simulation of compressible isotropic turbulence is suggested. A sixth order compact interpolation method is used for computing fluxes at the cell interfaces. Dynamic Smagorinsky Model (DSM) for compressible flows is used for LES. The flow solver is validated using various benchmark problems. Decaying isotropic turbulence is simulated using both DNS and LES. Turbulent statistics and energy spectra are compared. The LES method is found to effectively model the small scales of turbulent motion.

High temperature effects on high enthalpy flow over a double-wedge geometry are studied using a local thermodynamic equilibrium(LTE) based model for air. A finite volume based compressible flow solver is developed for this purpose. Effect of LTE based thermodynamic properties on the resulting flow field, shock distance and the type of shock interaction is studied. A parametric study is conducted by varying the upstream temperature, upstream Mach number and the wedge geometry individually.

Chemical and vibrational non-equilibrium effects on turbulence are studied using DNS. Such effects are typically observed in very high Mach number flows. Decaying isotropic turbulence is chosen as a model problem to study the physics underlying these non-equilibrium/turbulence interactions. A hybrid higher order finite difference based flow solver is developed for this purpose. A 5-species model for air is implemented. Turbulence/non-equilibrium interactions are studied for two different initial mean temperatures. Effects on both the mean flow and the turbulence are presented.

A finite volume based numerical method for simulating supersonic turbulent boundary layer over a flat plate is suggested. A sixth-order compact interpolation method is used for computing fluxes at the cell interfaces. A rescaling method for generating inflow turbulence is discussed to provide realistic inflow conditions at the inlet. DNS and LES are conducted for Mach 2 zero pressure gradient turbulent boundary layer. Mean velocity profiles and turbulent intensities are validated.