|February 27, 2008, 22:27||
implementation of agglomeration multigrid
I am currently implementing multigrid for unstructured grids (2d). I had successfully implemented a defect correction technique and obtained a good convergence rate for higher order solutions. Now, I am in process of implementing the agglomeration multigrid technique. I have some doubts regarding the treatment of coarser grids
1) How to determine the grid spacing (h) of coarser grid (arbitrary polygon) ? Or, how to decide the timestep to take in the coarser grid?
2) Restriction operation is done by injection (agglomeration). If I do a linear interpolation for prolongation, will it give a good convergence? Will the discontinuity at the coarse grid affect the convergence in the fine grid? I saw some implicit methods for prolongation. I was wondering if I should put the effort in doing that.
3) In the coarse grids can I have a first order approximation for convective fluxes and second order for viscous fluxes? I guess it would be more stable that way, and permit a relaxes time stepping in coarser grids.
4) Is there explicit algebraic multigrid technique for finite volume methods (without forming a big matrix). If so, can you give a reference?
Thanks in advance for your clarifications.
|Thread||Thread Starter||Forum||Replies||Last Post|
|LES by Multigrid||mnabi||Main CFD Forum||8||July 11, 2009 20:21|
|multigrid||sureshkumar||Main CFD Forum||0||June 9, 2006 01:20|
|local timestep for agglomeration multigrid method||Jian Xia||Main CFD Forum||3||March 20, 2000 12:20|
|Agglomeration multigrid to solve Euler equations||Jian Xia||Main CFD Forum||3||January 11, 2000 19:07|
|Multigrid applied to k-e models||Paulo Zandonade||Main CFD Forum||9||May 24, 1999 08:10|