The validity of using simplified models of compressible fluids for calculations of unstationary convection flows inside closed cavities is tested for the problem of hot gas cooling in a rectangular cavity with cold walls. The Oberbeck-Boussinesq approximation and other simplified models are shown to yield incorrect values of pressure, density, and temperature if average pressure change is not negligible. Modification of the numerical method is proposed, which allows one to describe the temporal dependence of pressure correctly without loss of computational efficiency. The results obtained by using a modified Oberbeck-Boussinesq approximation and the complete equations for a fully compressible fluid are compared.
44.25.+f Natural convection
Department of Molecular Physics, Faculty of Physics, Moscow State University, Moscow, 119991, Russia
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