Fast time implicit-explicit discontinuous Galerkin method for the compressible Navier-Stokes equations

  • Authors:
  • Florent Renac;Sophie Gérald;Claude Marmignon;Frédéric Coquel

  • Affiliations:
  • -;-;-;-

  • Venue:
  • Journal of Computational Physics
  • Year:
  • 2013

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Abstract

An efficient and robust time integration procedure for a high-order discontinuous Galerkin method is introduced for solving the unsteady compressible Navier-Stokes equations. The time discretization is based on an explicit formulation for the convective fluxes and an implicit formulation for the viscous fluxes. The implicit procedure uses a fast iterative algorithm based on a partial uncoupling of variables in neighboring elements introduced in previous works by the authors. In the present work, the method is associated to a Newton-Krylov Jacobian-free method. This association allows to reduce memory requirements and operation counts by avoiding the complete construction of the Jacobian matrix and solving a problem of reduced size. Numerical examples in two space dimensions indicate that the performance of the present method is seen to be significantly improved in terms of CPU time.