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Robust Low Mach Preconditioned Density-Based Methods

[ jeudi 17-11-2011 12:00 | anglais ]Robust Low Mach Preconditioned Density-Based Methods Leonardo Santos de Brito Alves Institut Militaire d'Ingenierie/Brésil
Résumé :
Preconditioning techniques for low Mach number compressible flow simulations have been used in the literature for the past two and a half decades. Their goal is to minimize stiffness and control cancellation errors present in high speed compressible flow codes attempting to simulate low speed problems. Despite their success, these techiniques still suffer from robustness issues that generate significant errors and might even prevent convergence. The present study shows that these issues are mostly caused by an ill-conditioned preconditioning matrix, and not only non-orthogonal eigenfunctions. A novel yet simple modification of the traditional preconditioning matrix is suggested. It leads to convergence rate enhancements as high as 300% when compared to the traditional approach employed in the literature.