In most models of reacting gas dynamics,the characteristic time scales of chemical reactions are much shorter than the hydrodynamic and diffusive time scales,rendering the reaction part of the model equations stiff.Moreover,nonlinear forcings may introduce into the solutions sharp gradients or shocks,the robust behavior and correct propagation of which require the use of specialized spatial discretization procedures.This study presents high-order conservative methods for the temporal integration of model equations of reacting flows.By means of a method of lines discretization on the flux difference form of the equations,these methods compute approximations to the cell-averaged or finite-volume solution.The temporal discretization is based on a multi-implicit generalization of integral deferred correction methods.The advection term is integrated explicitly,and the diffusion and reaction terms are treated implicitly but in- dependently,with the splitting errors present in traditional operator splitting methods reduced via the integral deferred correction procedure.To reduce computational cost,time steps used to integrate processes with widely-differing time scales may differ in size.
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