An implicit splitting scheme with characteristic boundary conditions for compressible reactive flows on unstructured grids

Abstract

The computation of combustion instabilities requires efficient numerical solvers. For low Mach number compressible flows splitting schemes provide an adequate family of solution strategies. Here, the set of governing equations is separated into several subsystems, e.g. into an advective and acoustic subsystem. Advancements for such an algorithm are presented improving accuracy and stability. Moreover a new, gradient based approach is given for coupling the splitting scheme with characteristic boundary conditions on collocated unstructured grids. A large number of academic test cases is chosen to demonstrate the accuracy and performance of the proposed improved numerical scheme. In addition, the improved solver is tested in a complex, non-reactive LES of a swirl combustor on an unstructured grid.