Simulation of a radiative gas flow near re-entry space vehicle
We consider a model problem of calculating a hypersonic radiating gas flow around a spacecraft as it moves in the upper atmosphere. The governing system of gas dynamics equations is considered in the two-dimensional approximation. We use cylindrical (r-z) geometry for calculations. Radiative-gasdynamic equations are solved by the method of physical splitting. Difference approximations to the governing system written in the form of conservation laws are built on a triangular unstructured mesh used in our calculations. The control volumes associated with the original grid are taken in the form of modified Voronoi diagrams. The gas dynamic system is solved by means of the generalized Tadmor-Kurganov difference scheme (2002). We implement a time-advance calculation by the two-step explicit predictor-corrector scheme. The developed technique provides a quite satisfactory flow resolution in space and time. However, to achieve more higher solution accuracy near a vehicle we use a dynamic mesh adaptation to the flow features. The conservative algorithm for calculating the radiation transfer is constructed on the basis of a grid-characteristic scheme. Air properties are taken into account via wide-range EOS, and emissivity and opacity datatables. We describe a methodology of constructing spectral-multigroup models for the absorption coefficients according to a given composition of gases forming the air. Good comparisons between results of our calculations with those obtained by T. Sakai, T. Tsuru and
K. Sawada (2001) in their numerical experiments with high accuracy numerical gasdynamic techniques, as well as with detailed spectral simulation techniques developed by C. Park and F. Milosh (1990) allows us to conclude that it is advisable to further extend our numerical methodology with the aim to solve applied problems.