Hightemp Technique of High Temperature Gas Flows Numerical Simulation

A brief description of effective Navier-Stokes (NS) numerical technique for high temperature gas flows simulation (HIGHTEMP) is given. The NS codes have been developed for various gas-phase models from perfect gas to thermally and chemically nonequilibrium multicomponent and multitemperature gas medium. Slip effects, finite rate energy exchanges, surface catalysis and ablation can be taken into account in the wall boundary conditions. The software package HIGHTEMP involves codes for radiative heat transfer (RHT) computations. Several turbulence models for calculation of turbulent flows can be employed. For numerical integration of NS and RHT equations TVD type finite volume schemes are used. The solvers have been adopted for parallel high performance computing systems using MPI-technology. Some numerical results obtained with developed technique are presented. INTRODUCTION The development of the robust, efficient and handly numerical technique for gas flow simulation in a wide pressure, temperature and chemical composition range is a challenging task. HIGHTEMP computing system (CS HIGHTEMP) is elaborated in Institute of Mechanics Moscow State University to provide researches of high velocity aerodynamics, heat transfer and supersonic combustion (Gromov V. G., 2002). The HIGHTEMP technique is based on a software package of NS solvers integrated with thermochemical databases. The NS solvers are developed for three levels of the high temperature thermochemical gas-phase models from perfect gas to multitemperature and multicomponent ionized gas medium. Nonequilibrium chemical reactions, ionization, relaxation of internal energy modes can be included in a kinetic model with consideration their coupling. Gas-phase models can be used with various gas-wall interaction models. Slip effects, finite rate energy exchanges, surface catalysis and ablation can be taken into account in formulation of the boundary conditions. The numerical modeling of flows for high Reynolds numbers is carried out in the framework of Favre-averaged Navier-Stokes equations. The Boussinesq approximation for the turbulent fluxes simulation and several turbulence models for calculation of turbulent transport coefficients can be employed. The NS equations are solved on the multiblock structured mesh through a finite volume approach. The inviscid fluxes across cell faces are calculated from result of the exact Riemann problem solution. The interfacial values are defined by the limited onedimensional extrapolation of primitive variables from the cell-centers to the cell faces. The numerical viscous fluxes across cell faces are evaluated using the central and one-sided difference formulas of the second order accuracy. Steady-state solution is defined due implicit iterative procedure. On the every iteration the flowfield parameters are computed due Gauss-Seidel line relaxation numerical method. For time-marching integration of time-dependent NS equations the implicit Runge-Kutta scheme of second order accuracy is used. The NS solvers have been adopted for parallel high performance computing systems using MPI-technology. The software package HIGHTEMP involves codes for radiative heat transfer computations. RHT equations are solved on the same mesh also through finite volume approach. Multigroup optical model is used to calculate absorption and emission coefficients (Surzhikov S.T., 2000). The some examples of CS HIGHTEMP application to Earth and Mars atmospheres entry and flow in discharge channel of plasmatron are presented.