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Showing results 1 to 17 of 17 Search took 0.00 seconds. Search: Posts Made By: alberto

Forum: OpenFOAM May 22, 2011, 21:23

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto Good! This confirms that the flow is not steady,... Good! This confirms that the flow is not steady, and you need to resolve it in time, which is not possible with simpleFoam. If possible, try to make a movie of the flow: you will probably notice...

Forum: OpenFOAM May 15, 2011, 04:04

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto Hi, since the LES captures the flow... Hi, since the LES captures the flow properly, and it is an unsteady simulation (I assume you averaged the results in time), probably the steady solution is not representing the system properly...

Forum: OpenFOAM April 26, 2011, 17:23

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto Nothing seems evidently wrong. Is the solution... Nothing seems evidently wrong. Is the solution converging to a low value of the initial residuals in the iterations? To see if it depends on the numerical diffusion, since you run steady cases,...

Forum: OpenFOAM April 25, 2011, 04:44

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto OK. Just do a search on the source of these data.... OK. Just do a search on the source of these data. Unfortunately "published result" does not mean "bulletproof". A good indication of the quality of results is the presence of estimates of uncertainty...

Forum: OpenFOAM April 25, 2011, 00:24

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto What numerical schemes do they use? And what is... What numerical schemes do they use? And what is the order of magnitude of the velocity? The question is: do you really resolve the scales as you should do in a LES? If so, the anisotropic scales...

Forum: OpenFOAM April 22, 2011, 11:32

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto Well "far from experiment" is a bit vague,... Well "far from experiment" is a bit vague, because it might simply depend on the setup, on the choice of the model or on the grid resolution. If you use Smagorinsky, you do LES and you should do...

Forum: OpenFOAM April 11, 2011, 14:50

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto Upwind is a first order scheme, while... Upwind is a first order scheme, while limitedLinear is a limited second-order central difference scheme. As a consequence you should have better accuracy with the limitedLinear scheme. You...

Forum: OpenFOAM April 11, 2011, 12:04

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto If you use the same schemes in both 2D and 3D, I... If you use the same schemes in both 2D and 3D, I would say it does not depend on them :-) Is the mesh resolution in 2D and 3D comparable, and the distribution of points along the radius of the...

Forum: OpenFOAM April 9, 2011, 15:07

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto You are probably not using a good enough mesh in... You are probably not using a good enough mesh in the core of the cyclone. Quick hints: - use a hex-dominant mesh, if you are not doing it already - refine the core area (you can define a cylinder...

Forum: OpenFOAM September 27, 2010, 15:13

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto Cyclone simulations are a typical case where RSM... Cyclone simulations are a typical case where RSM models are required to have a proper flow description of the vortex, since the flow is anisotropic. Not a surprise RSM performs significantly better...

Forum: OpenFOAM September 24, 2010, 17:21

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto You are actually using the linear scheme for... You are actually using the linear scheme for div(phi, U), which might explain the poor convergence/results on a coarse mesh. Try using the attached files, starting from the original initial...

Forum: OpenFOAM September 21, 2010, 13:33

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto The problem is hardly the number of cells in your... The problem is hardly the number of cells in your case but the case setup, and there we can be of no help without a case that reproduces the problem.

Forum: OpenFOAM September 15, 2010, 10:36

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto Does poor results mean very diffused? ... Does poor results mean very diffused? The linear solver should not play any role, as long as the required convergence criterion is the same. However it is difficult to answer without...

Forum: OpenFOAM September 15, 2010, 10:33

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto First of all run checkMesh on your grid. If... First of all run checkMesh on your grid. If results are very poor with a second order discretization in RANS cases, you either have some mistake in the setup or a poor mesh. Additionally, I think...

Forum: OpenFOAM April 23, 2010, 14:17

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto You can still use second order schemes, but using... You can still use second order schemes, but using limiters, usually without any need to go back to first order schemes. In your scheme settings, you might have a problem with div(phi,U) Gauss...

Forum: OpenFOAM April 23, 2010, 00:18

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto Try to see if there is some point in particular... Try to see if there is some point in particular in the mesh where the solution is not correct. Can you post your fvSchemes and fvSolution too?

Forum: OpenFOAM April 16, 2010, 02:22

Replies: 43 simpleFoam convergence on large domain Views: 12,820 Posted By alberto checkMesh is failing because you have highly... checkMesh is failing because you have highly skewed cells (and also some strongly non-orthogonal cell) The second problem can probably be corrected indirectly with non-orthogonal correctors in the...

Showing results 1 to 17 of 17

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