A Multigrid Approach to Embedded-Grid Solvers
Interim rept. Jan 1991-Apr 1992
WRIGHT LAB EGLIN AFB FL
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The explicit first order flux difference splitting FDS is used to solve the equations governing inviscid fluid flow on a single grid for the 5 degree ramp and the 5 degree ramp near a flat plate. Calculations were made for the Mach 2 case using local time stepping at a Courant number of 0.96. The multigrid full approximation scheme FAS is applied to this non-linear problem to provide increased convergence rates and reduced central processing unit CPU time requirements. Several systems of embedded grids are implemented to provide increased accuracy near shock waves. Embedded grids were aligned with the shocks to take advantage of the excellent shock capturing capability of the FDS scheme. The nonaligned multigrid is introduced to provide increased convergence for the embedded grid systems by treating the individual grids as levels in the multigrid solution procedure. This technique is able to converge 69 faster than the embedded grid procedure for the 5 degree ramp, and 28 faster for a more complex reflected shock case. Computational Fluid Dynamics CFD, Multigrid, Chimera EmbeddedOverset grids, Nonaligned Multigrid Euler Equations.
- Fluid Mechanics