Maximilian Emans: February 22, 2011

A pressure-enthalpy coupling algorithm for CFD using AMG to solve mixed elliptic-hyperbolic systems

Maximilian Emans,  AVL List GmbH, Graz

Tuesday, February 22, 5:00 p.m. in the CERFACS conference room

Abstract:

This talk is dedicated to linear systems of mixed elliptic-hyperbolic character. These systems appear in many simulation applications, e.g. oil reservoir simulations and CFD. In the first part of the talk we focus on CFD and present a novel method to solve the Navier-Stokes equation for problems with variable density. The method, referred to as SIMPLE-H, is deduced from common implicit SIMPLE algorithm. Its novelty lies in simultaneous solution of pressure-correction and energy equation; the coupled linear system is of mixed elliptic-hyperbolic type. It is demonstrated that SIMPLE-H has a superior convergence, especially in combination with combustion models and LES. The second part of the talk is on efficient solution techniques for linear systems of mixed elliptic-hyperbolic type. We focus on algebraic multigrid methods for this class of problems and in particular on technical aspects of the coarse-grid treatment. We present an efficient implementation of an agglomeration scheme for coupled systems. By a benchmark from engineering practice we compare it to existing approaches including the employment of MUMPS and show that it preserves the desired multigrid behaviour not only in terms of convergence but also in terms of run-time on distributed memory computers.