AN IMPLICIT MULTIGRID METHOD FOR THE SIMULATION OF CHEMICALLY REACTING FLOWS

The application of multigrid methods is complicated if the set of gove rning equations contains strongly nonlinear source terms. This is the case for finite-rate chemistry as well as for turbulence conservation equations. In most cases strong nonlinearities within the chemical pro duction rates prevent convergence of standard multigrid methods. This paper investigates different approaches to treating chemical and turbu lent production terms on coarse grids in order to enable convergence. Independent of combustion, supersonic flows require special care durin g restriction and prolongation if strong shock waves occur. A full coa rsening four-level nested multigrid method is used for all conservatio n equations including those of turbulence and species transport. Stron g convergence accelerations are achieved by a local source term-depend ent damping of the restricted residual error. Several test cases with and without combustion demonstrate the efficiency and accuracy of the proposed multigrid algorithm. (C) 1998 Academic Press.