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Search took 0.00 seconds. Search: Posts Made By: alberto
Forum: OpenFOAM Bugs December 21, 2010, 14:58
Replies: 90
Views: 14,023
Posted By alberto
Relaxation is applied implicitly before solving...

Relaxation is applied implicitly before solving if you do:

yourEqn = ...;
yourEqn.relax();
yourEqn.solve();

If you see the relax() method applied to a field (like p in simple algorithm), you...
Forum: OpenFOAM Bugs December 7, 2010, 02:12
Replies: 90
Views: 14,023
Posted By alberto
You have to upload them somewhere and use the...

You have to upload them somewhere and use the yellow button with the mountains in the toolbar, or attach them as files (clip icon).

Best,
Forum: OpenFOAM Bugs November 7, 2010, 00:31
Replies: 90
Views: 14,023
Posted By alberto
Well, as I told you, actually this is not the...

Well, as I told you, actually this is not the leading way of thinking. In most of the cases the BC is imposed weakly exactly to avoid numerical difficulties.

Anyway, I did what you said (took...
Forum: OpenFOAM Bugs November 5, 2010, 18:28
Replies: 90
Views: 14,023
Posted By alberto
Do you use under-relaxation or use an unsteady...

Do you use under-relaxation or use an unsteady solver (did you set steadyState in fvScheme?)?

The results I posted above are obtained exactly using Hrv case, with upwind scheme, obtaining a steady...
Forum: OpenFOAM Bugs November 5, 2010, 17:59
Replies: 90
Views: 14,023
Posted By alberto
In his case DT is large, that's why you get the...

In his case DT is large, that's why you get the right answer. :)
Forum: OpenFOAM Bugs November 5, 2010, 16:57
Replies: 90
Views: 14,023
Posted By alberto
If you set DT = 0.001, with that case, without...

If you set DT = 0.001, with that case, without relaxing, refining the grid next to the outlet and/or using a small time stepping in the case of unsteady runs, you won't get the correct solution for...
Forum: OpenFOAM Bugs November 5, 2010, 15:16
Replies: 90
Views: 14,023
Posted By alberto
I think we are mixing things (sorry if I...

I think we are mixing things (sorry if I contributed to that).

We are talking about upwind schemes, not central schemes, which we all know have a stability condition on the Peclet number.

Now,...
Forum: OpenFOAM Bugs November 5, 2010, 12:33
Replies: 90
Views: 14,023
Posted By alberto
Yes, I am aware of it, but your problem does not...

Yes, I am aware of it, but your problem does not originate from the numerical scheme, but from the solution of the linear system originated from the discrete equation.

Reducing the step just...
Forum: OpenFOAM Bugs November 5, 2010, 09:56
Replies: 90
Views: 14,023
Posted By alberto
Santiago, the case with DT = 0.01 works fine. ...

Santiago, the case with DT = 0.01 works fine.

The case with DT = 0.001 will give you problems (you have no points in the BL). Refine the grid around the outlet (I know I am changing the conditions...
Forum: OpenFOAM Bugs November 3, 2010, 16:51
Replies: 90
Views: 14,023
Posted By alberto
The original had a relatively low diffusivity,...

The original had a relatively low diffusivity, which probably made Santiago think to an instability. Then the discussion deviated on something else, admittedly not correct.

P.S. Please let us know...
Forum: OpenFOAM Bugs September 29, 2010, 18:30
Replies: 90
Views: 14,023
Posted By alberto
Yes, physically this is what happens. But the...

Yes, physically this is what happens. But the numerical setup that gives you problems does not say exactly that, due to the upwind interpolation.



Just think to a condition where the imposed...
Forum: OpenFOAM Bugs September 29, 2010, 14:30
Replies: 90
Views: 14,023
Posted By alberto
Call me stubborn :D, but I am not convinced of...

Call me stubborn :D, but I am not convinced of the need of messing with the interpolation schemes to solve this problem. I'll try to explain.

Let's examine first what happens physically in your...
Forum: OpenFOAM Bugs September 29, 2010, 09:37
Replies: 90
Views: 14,023
Posted By alberto
Let's assume we implement your approach. What...

Let's assume we implement your approach. What value do you assign to the face when you store the solution? You end up with two different values at the same face...

Maybe I am a bit stubborn :-),...
Forum: OpenFOAM Bugs September 27, 2010, 15:04
Replies: 90
Views: 14,023
Posted By alberto
After thinking about it a bit more, I tend to...

After thinking about it a bit more, I tend to think what is done in OpenFOAM is correct, even if probably not the expected behaviour. I see a boundary condition as an information specified by the...
Forum: OpenFOAM Bugs September 26, 2010, 15:05
Replies: 90
Views: 14,023
Posted By alberto
Since I had some doubt this "problem" has been...

Since I had some doubt this "problem" has been left there for so long, I wrote to Hrv to ask for explanations :D

He replied that indeed it is not a bug in the fvm::div operator, but it depends on...
Forum: OpenFOAM Bugs September 26, 2010, 00:51
Replies: 90
Views: 14,023
Posted By alberto
I would like to ask some more comment on Mantis,...

I would like to ask some more comment on Mantis, but it seems the bug cannot be re-opened once closed (or I am not familiar enough with that bug-reporting tool). Any idea if that's possible?
Forum: OpenFOAM Bugs September 24, 2010, 10:42
Replies: 90
Views: 14,023
Posted By alberto
Thanks eugene for the clarification. One...

Thanks eugene for the clarification.

One question. Does this problem affect the -dev/-ext release too?



It might be the nature of open source, but OpenFOAM is also a CFD code used for...
Forum: OpenFOAM Bugs September 23, 2010, 01:13
Replies: 90
Views: 14,023
Posted By alberto
Hi, you said the problem happens with upwind...

Hi,

you said the problem happens with upwind scheme. Is it limited to it? Did you try to use the linear scheme with an appropriate grid to satisfy the stability criterion?

Best,
Forum: OpenFOAM Bugs September 21, 2010, 14:35
Replies: 90
Views: 14,023
Posted By alberto
I think they follow this forum.

I think they follow this forum.
Forum: OpenFOAM Bugs September 21, 2010, 13:27
Replies: 90
Views: 14,023
Posted By alberto
OK. I found the bug report. Sorry, for some...

OK. I found the bug report. Sorry, for some reason my browser was not refreshing the page.

I see the problem too.
Forum: OpenFOAM Bugs September 21, 2010, 02:43
Replies: 90
Views: 14,023
Posted By alberto
Hello, you are saying that if a fixedValue...

Hello,

you are saying that if a fixedValue condition is specified, and the condition is basically an outlet with a fixed value for a given property, that value is enforced?

If so, isn't it the...
Showing results 1 to 21 of 21

 
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