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Informal Seminar by Wei Liao |
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Date: June 21, 2007
Time: 1:30 pm
*This is a "mini-seminar" lasting approximately 30 minutes*
Location: NIA, Room 137
Textbook-Efficiency Multigrid Solver for Three-Dimensional Unsteady Compressible Navier-Stokes Equations
Dr. Wei Liao, Old Dominion University
Implicit time-integration techniques are envisioned to be the method of choice for direct numerical simulations (DNS) at high Reynolds numbers. Therefore, the computational efficiency of implicit flow solvers becomes critically important. The textbook multigrid efficiency (TME), which is the optimal efficiency of a multigrid method, is achieved if accurate solutions of the governing equations are obtained with the total computational work that is a small (less than 10) multiple of the operation count in one residual evaluation. In this talk we present a TME solver for unsteady subsonic compressible Navier-Stokes equations in three dimensions discretized with an implicit, second-order accurate in both space and time, unconditionally stable, and non-conservative scheme. A semi-Lagrangian approach is used to discretize the time-dependent convection part of the equations and viscous terms and the pressure gradient are discretized on a staggered grid. TME solver for the implicit equations is applied at each time level. The efficiency of the proposed solver does not deteriorate for flows at high Reynolds numbers and for large time steps.
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