High accuracy simulation of viscous unsteady gasdynamic flows

Abstract

This chapter shows that the kinetically consistent finite difference (KCFD) schemes may be interpreted as a physical model for the description of viscous gasdynamic flows. This model is based on the representation of one particle distribution function as a Maxwellian particle constant on cells of size equal to the free length path. The dissipative terms of KCFD schemes are formed by two different “half-Maxwelian” distribution functions taken from both sides of a cell edge. The description of viscous unsteady separate flows providing a high accuracy flow simulation is exact for modem aerospace investigations. Using such mathematical description it is possible to obtain a set of frequencies relating to pressure oscillations generated by different scale vortices. The predictions of unsteady flow over the cavity with the parameters specified have been carried out with the use of various time and space grids. The reduction of time step does not result in any essential change of spectral characteristics of pressure pulsation. Use of more refined space meshes permits to reveal some additional features of flow structure within the cavity as well as to investigate the mechanism of discrete modes generation in pressure pulsation spectrum in detail. To predict a detailed structure of unsteady viscous compressible flows, high performance parallel computer systems need to be used. KCFD schemes are ideally adapted to parallel computers with distributed-memory architecture and provide the real opportunity for a high accuracy prediction of unsteady flows.