MULTIGRID PRECONDITIONING OF THE STEAM GENERATOR TWO-PHASE MIXTURE BALANCE EQUATIONS IN THE GENEPI SOFTWAREReport as inadecuate




MULTIGRID PRECONDITIONING OF THE STEAM GENERATOR TWO-PHASE MIXTURE BALANCE EQUATIONS IN THE GENEPI SOFTWARE - Download this document for free, or read online. Document in PDF available to download.

1 LMEC - DEN-DM2S-STMF-LMEC 2 LMDL - Laboratoire de Modélisation et de Développement des Logiciels

Abstract : In the framework of the two-phase fluid simulations of the steam generators of pressurized water nuclear reactors, we present in this paper a geometric version of a pseudo-Full MultiGrid pseudo-FMG Full Approximation Storage FAS preconditioning of balance equations in the GENEPI code. In our application, the 3D steady state flow is reached by a transient computation using a semi-implicit fractional step algorithm for the averaged two-phase mixture balance equations mass, momentum and energy for the secondary flow. Our application, running on workstation clusters, is based on a CEA code-linker and the PVM package. The difficulties to apply the geometric FAS multigrid method to the momentum and mass balance equations are addressed. The use of a sequential pseudo-FMG FAS two-grid method for both energy and mass-momentum balance equations, using dynamic multigrid cycles, leads to perceptibly improvements in the computation convergences. An original parallel red-black pseudo-FMG FAS three-grid algorithm is presented too. The numerical tests steam generator mock-up simulations underline the sizable increase in speed of convergence of the computations, essentially for the ones involving a large number of freedom degrees about 100 thousand cells. The two-phase mixture balance equation residuals are quickly reduced: the reached speed-up stands between 2 and 3 following the number of grids. The effects on the convergence behavior of the numerical parameters are investigated.





Author: Michel Belliard - Marc Grandotto -

Source: https://hal.archives-ouvertes.fr/



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