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-   -   Multigrid controls? (http://www.cfd-online.com/Forums/fluent/28061-multigrid-controls.html)

David December 2, 2000 23:04

Multigrid controls?
 
I am a new user to Fluent. Actually what is the function of multigrid controls under solve>control panel. Any suggestion is appreciated.

Dan Williams December 12, 2000 23:52

Re: Multigrid controls?
 
The fact that Fluent even provides these controls in the GUI is quite hilarious. Basically it says to me that they do not have the technical knowledge to figure out how to make their multigrid solver work well, and leave it to the user to tweak it until they get it right.

If you want to know more about multigrid though, a decent starting point is the Multigrid Tutorial by Briggs I think? Check in the information section on this website, I'm sure there is a reference on the CFD books section.

Other than that, read their user doc.

Dan.

Dark Pain January 19, 2001 16:33

Re: Multigrid controls?
 
Have you ever actually used Fluent? You reply to a lot of questions, but you seem to lack any real knowledge. In all the cases I've run with Fluent, I've never had to adjust the multigrid controls. Its nice that they are there if I should want to modify them, but it isn't necessary.

John C. Chien January 20, 2001 01:50

Re: Multigrid controls?
 
(1). The multi-grid issue is an important one. So, any comment or information is welcome here.(2). My experience with the code is: for the incompressible module (in UNS days), normally there is no need to fool around the setting, because the convergence rate is normally fast (faster than the Rampant module). (3). For the compressible flow module (in Rampant days), it normally did not work. In other words, trying to use multi-grid would encourage divergence. So, multi-grid option was not used for the compressible module. (4). Negative comments are extremely important for the forum, because it tends to encourage readers to present the positive experience, if such experience exists. (5). if we only present positive experience about the codes, both the users and the vendors will eventually die. (6). By the way, an expert does not need to have ahnds-on experience in order to make comments. The readers come here to learn from other reader's experience, he does not come here to hear the good news only. We welcome any comment from readers, especially those who are experts. For readers, it is important to read the contents of the question and the answer, but not the name itself. When one is preoccupied, it is hard to learn something new.


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