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Search: Posts Made By: msrinath80
Forum: OpenFOAM Running, Solving & CFD June 24, 2007, 22:44
Replies: 9
Views: 12,632
Posted By msrinath80
To my knowledge, multi-grid is

To my knowledge, multi-grid is merely a solution approach. Deep down it also uses conventional solvers such as the conjugate gradient. So I don't quite see why the final result would be affected...
Forum: OpenFOAM Running, Solving & CFD June 24, 2007, 12:30
Replies: 9
Views: 12,632
Posted By msrinath80
Oh, and by the way, if you use

Oh, and by the way, if you use a uniformly spaced purely orthogonal grid, I've noticed that changing

mergeLevels 1;

to

mergeLevels 2; or even mergeLevels 3; speeds up the GAMG solver.
Forum: OpenFOAM Running, Solving & CFD June 24, 2007, 12:26
Replies: 9
Views: 12,632
Posted By msrinath80
Check the older posts in the f

Check the older posts in the forum[1,2]. If I recall correctly, I think the recommendation was anything from a dozen to a couple hundred cells in Serial mode and around 20-30 cells in Parallel mode....
Forum: OpenFOAM Running, Solving & CFD June 12, 2007, 06:22
Replies: 9
Views: 12,632
Posted By msrinath80
Here is a recent OpenFOAM pres

Here[1] is a recent OpenFOAM presentation on the multi-grid solver.

Check out slide 29 'Computational examples' to see what I meant earlier.

[1]...
Forum: OpenFOAM Running, Solving & CFD June 12, 2007, 04:35
Replies: 9
Views: 12,632
Posted By msrinath80
Apologies. I should have elabo

Apologies. I should have elaborated. By decent discretization, I refer to pure orthogonal grids with 0 skewness. Check out this[1] thread for more details.

[1]...
Forum: OpenFOAM Running, Solving & CFD June 12, 2007, 03:25
Replies: 9
Views: 12,632
Posted By msrinath80
Why do you need tolerance 1e-

Why do you need tolerance 1e-08? Won't 1e-06 do? How bad is your mesh? Do you use non-conformal faces (i.e. hanging nodes)? AMG will give very good results provided the discretization is decent and...
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