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Bob April 10, 2002 08:19

time-variant boundary profile

As inlet boundary condition I would like to impose measurement data, and not a function. As long as one is dealing with constant (in time) boundary conditions it is fairly easy to implement. But what about time-varying data? Does somebody know how to deal with this in Fluent?

Thanks a lot in advance!

Best regards, Bob De Clercq

Johnix April 10, 2002 13:55

Use UDF ...
There are examples in Fluent "user's guide" which deal with unsteady inlet profiles by means of employing UDF(user defined functions)

Recently, I have writen a UDF code to modify boundary conditions, and it does work.

riccardo May 1, 2002 12:57

Re: time-variant boundary profile
Hi!! You can use the User defined Function, to define a time varyng law, and than apply this law to the every boundary you need.

This is the function ---------------------------------------- #include "udf.h" DEFINE_PROFILE (nameofprofile, thread, position) { face_t f; begin_f_loop (f,thread) { real t = RP_Get_Real ("flow-time"); F_PROFILE(f, thread, position) = 300. - 100*t; } end_f_loop (f, thread) } ------------------------------------------- you have to save it on file .c (is written on C language!!): than go to menu DEFINE---USER DEFINED FUNCTION---INTERPRETED---- than you have to insert the name of the file (put it on the same directory you ' ve loaded the case), and than click on compile. After doing this job, on the mask to set the condition of the boundary you can see CONSTANT and also your profile!! Hi!!

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