A Multigrid Approach to Embedded-Grid Solvers

Abstract

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 Embedded/Overset grids, Nonaligned Multigrid Euler Equations.

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Document Details

Document Type
Technical Report
Publication Date
Aug 01, 1992
Accession Number
ADA256405

Entities

People

  • Rudy A. Johnson

Tags

DTIC Thesaurus Topics

  • Accuracy
  • Air Force
  • Central Processing Units
  • Computational Fluid Dynamics
  • Computational Science
  • Computers
  • Convergence
  • Difference Equations
  • Differential Equations
  • Eigenvalues
  • Equations
  • Euler Equations
  • Fluid Dynamics
  • Fluid Flow
  • Grids
  • Partial Differential Equations
  • Shock Waves

Fields of Study

  • Physics

Readers

  • Combustion Dynamics and Shock Wave Physics.
  • Computational Fluid Dynamics (CFD)
  • Finite Element Method (FEM) for solving Partial Differential Equations (PDEs)