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msrinath80 May 29, 2007 13:51

In OF 1.3, we used the followi
In OF 1.3, we used the following syntax in the fvSolution file:

p AMG 1e-06 0 25;

If I were to translate the same into OF 1.4, I would expect the following syntax:

tolerance 1e-06;
relTol 0;
nCellsInCoarsestLevel 25;


My question is whether we need to specify nPreSweeps, nPostSweeps and nFinestSweeps? Also, can someone explain the use of mergeLevels?

Also what smoothers are available?

Many thanks!

eugene May 31, 2007 11:55

mergeLevels is the number of m
mergeLevels is the number of merge operations to do between grid levels. mergeLevel 1 is equivalent to what is hard coded in AMG and is what I normally use.

agglomerator faceAreaPair; seems to work best

smoother options are: GaussSeidel, DIC and DICGausSeidel. GausSeidel seems to work best, but DICGaussSeidel might be better for more difficult problems. It is more expensive though.

nPreSweeps, nPostSweeps, nFinestSweeps: I use 0,2,2 and this should work for most problems. Feel free to experiment though.

msrinath80 May 31, 2007 15:28

Many thanks for that clear exp
Many thanks for that clear explanation Eugene!

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