[coewgb]

Hello,
I am trying to add a source term to the momentum equation by udf, and if I started the calculation, the error "receive a fatal signal(Segmentation fault)" will occur.

One of the udf codes is as below, and if I replace "C_T_G(cell,thread)[0]" with a constant value (e.g. 1.0), the calculation can be successfully started without the error. I just wonder the problem and how I can solve it.

DEFINE_SOURCE(cell_x_source, cell, thread, dS, eqn)
{
real source;
source = Cphi*C_UDSI(cell,thread,0)*C_T_G(cell,thread)[0] + C_R(cell, thread)*(C_U(cell,thread)*C_DUDX(cell, thread)+ C_V(cell, thread)*C_DUDY(cell, thread));
dS[eqn] = C_R(cell, thread)*C_DUDX(cell, thread);
return source;
}

Thanks a lot.

[pakk]

You have done a good job in identifying which part of your code gives the problems, it is the macro "C_T_G".

The next step is to look in the manual, what it says about this macro. Did you do this, and see the remark about "Keep temporary solver memory from being freed?"?

[coewgb]

Hello, pakk.
Thank you very much for your reply, it really worked.
Could you please help me with another problem?
When I moved on with the calculation using my udf, the residual of the uds equation kept 0 all the time, and the udf seemed to have no impact on the results. However, I did set the momentum source, uds flux, uds diffusion coefficient, uds source as well as the corresponding boundary conditions.
Did I miss other details when setting uds?
Thanks.

[pakk]

It looks like Fluent thinks that your UDS is zero everywhere.
Find out why that is (mathematically) not a solution to your problem. But it could be that you specified your problem in such a way that the zero solution is valid.

Tip: you should in most cases be able to find a boundary condition where you set the value of the UDS directly. If you set this to a non-zero value, then your UDS solution has to be non-zero.

(I am basing this answer on very little knowledge about your simulation, so it it is just my best guess at what the problem is.)

[coewgb]

Thank you for your quick reply. I will try to follow your tips and fix the boundary conditions.