CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   FLUENT (http://www.cfd-online.com/Forums/fluent/)
-   -   Help -----------udf (http://www.cfd-online.com/Forums/fluent/41330-help-udf.html)

mech June 9, 2006 08:58

Help -----------udf
 
Hi Is it possible to use two UDFs consecutively in the same simulation? If possible, how? Thanks Mech

Tom June 9, 2006 10:25

Re: Help -----------udf
 
As long as the UDFs are affecting different things, like a DEFINE_PROFILE and a DEFINE_SOURCE, or defining different sources, like an x-moment source or y-moment source, they can be used simultaneously.

If you want to have two things affecting, say, x-momementum at the same time, your best bet is to merge the UDFs together.

Hope this helps, Tom

mech June 10, 2006 00:39

Re: Help -----------udf
 
Tom Thank you for you response. I am working with microflow. First I simulate flow with noslip condition. After converging I impose slip boundary condition on it. Now I want to use uniform flow condition(not parabolic i.e. u(y)=constant)at inlet condtion for no slip boundary condition where I have to use define pofile. Then I have to impose slip condition using define profile. So I need two UDFs. In the same UDF it is not possible. If you have more idea about it please help me. Also For single devivative like du/dx I can use C_DUDX(c,t) but for higher derivative like momentum source term d2u/dy2,d2u/dxdy or d2v/dy2 which macro are to be used or how to write these terms in UDF. Have a nice time. Bye Mech

adriano June 10, 2006 06:49

Re: Help -----------udf
 
Hi, maybe the best way to do is use a switch law macro, U can find that in UDF Manual. For d2u/dy2 I think u must implemente a simple incremental ratio such as (delta(du/dx))/dx in your UDF. I hope it's helpfull

Regard

Adriano

mech June 15, 2006 08:59

Re: Help -----------udf
 
Hi Adriano Where is switch law macro? Will you mention the section number of the manual? Also I tried for 2nd order derivative but it is unmanagable. If you know I request you to clarify. Thanks Mech


All times are GMT -4. The time now is 12:32.