# How to add a source term in u or v equation?

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 December 12, 2004, 06:41 How to add a source term in u or v equation? #1 luckyluke Guest   Posts: n/a Hi,I am a newby and I want to add a source term in u or v momentum equation. The added source term at a certain grid point can be thought as a forcing term which is calculated form the values of neighbouring points. Besides the integral of u or v in the time direction is also needed. Who can help me and give some advice?

 December 12, 2004, 12:55 Re: How to add a source term in u or v equation? #2 Boris Morton Guest   Posts: n/a I think to add a source term you have to propagate the Navier Stokes equation into a polar variable format. When you do this it will be possible to take the exponential of the resulting force. After that stage simply use a double fourier series to approximate the possible eingevector terms. With this you should be able to import into CFD. Hope this helps Boris Morton

 December 13, 2004, 02:34 Re: How to add a source term in u or v equation? #3 luckyluke Guest   Posts: n/a I want to finish my question using PLANT or the other features provided by Phoenics. I implemented this using the UDF of Fluent. In my UDF, I define global variables which are needed all the solving process and I do loop in a sub-domain using C language(in the loop, the neighbouring cell-values are used), then by a source-term-Macro called "DEFINE_SOURCE" I add the computed source term to my momentum equations. Now, I want to do it in Phoenics. Is it possible? 0. Use Plant? 1. How to define global variables? 2. How to do a loop in a sub-domain? 3. How to get the neighbouring cell-values of a cell considered? 4. Where to add the computed source term? The docs of Phoenics are so boring and I have read them for a few days. But I have not got the idea. Pls help the stupid newbie.

 December 13, 2004, 02:52 Re: How to add a source term in u or v equation? #4 Volker Guest   Posts: n/a Hi, I am not aware of the new features in Phoenics since V3.4 but I think there are some news in later versions that might facilitate your task. Extra source terms for any variable can be defined in Inform. In how far neighbouring cell values can be used depends (in V3.4) on the grid that you use. Only in cartesian coordinates is it possible to refer to neighbour cell values in inform (see polis entry on inform). A global variable may be defined (in V3.4) as a whole-field stored variable that can then be addressed in Inform. regards Volker