Learning Forum

[pourya.heidari]

DEAR all

I want to simulate the laser welding with the FLUENT. I just activate the solidification and melting (without VOF). I face a problem to import the Marangoni effect into my simulation. In the BOUNDARY CONDITION (MARANGONI STRESS), I found the formula for surface tension gradient variation base on the temperature. Since I could not import the surface tension gradient by UDF in the MARANGONI STRESS, I try to import this effect by UDF in the SPECIFIED SHEAR. I attach the formula for this part and shot screen of specified stress.

 

 

 

To be honest, I do not know which Macro I should use to write this formula. I try DEFINE_PROPERTY and DEFINE_PROFILE. In my UDF, I consider the surface tension graidient as a constant. Everytime I run this code, Fluent would close. It is very painful. Please help me to find the error of this UDF.

Here you can find the UDF that I wrote for this part.

DEFINE_PROFILE(marangonix, t, i)

{

face_t f;

cell_t c;

Thread *tc;

real grad_temp, gama_temp;

begin_f_loop(f,t)

{

c=F_C0(f,t);

tc = THREAD_T0(t);

//tc=F_C0_THREAD(f,t);

grad_temp= C_T_G(c,tc)[0];

gama_temp=-0.00043;

F_PROFILE(f,t,i)=gama_temp*grad_temp;

}

end_f_loop(f,t)

}

 

DEFINE_PROFILE(marangoniy, t, i)

{

face_t f;

cell_t c;

Thread *tc;

real grad_temp, gama_temp;

begin_f_loop(f,t)

{

c=F_C0(f,t);

tc = THREAD_T0(t);

//tc=F_C0_THREAD(f,t);

grad_temp= C_T_G(c,tc)[1];

gama_temp=-0.00043;

F_PROFILE(f,t,i)=gama_temp*grad_temp;

}

end_f_loop(f,t)

}

 

DEFINE_PROFILE(marangoniz, t, i)

{

face_t f;

cell_t c;

Thread *tc;

real grad_temp, gama_temp;

begin_f_loop(f,t)

{

c=F_C0(f,t);

tc = THREAD_T0(t);

//tc=F_C0_THREAD(f,t);

grad_temp= C_T_G(c,tc)[2];

gama_temp=-0.00043;

F_PROFILE(f,t,i)=gama_temp*grad_temp;

}

end_f_loop(f,t)

}

 

[RK]

Hello, 

What is the error message that you are getting? It would be sometimes easier to debug knowing the error message and where to look at. 

[pourya.heidari]

Thank you Ruhal.

It gives the following error and then it close the FLUENT in few seconds. I feel deep pain with this error. I do not know why it closes the software. 

[RK]

This could be a systems related issue, can you please try to run it without UDF to see if the simulation runs fine? We could then narrow down the issue to UDF. 

[pourya.heidari]

Dear Rahul 

I tried it without UDF. It works fine, and the results are reasonable. I am sure that the error is because of the UDF. I can not debug the UDF. 

[DrAmine]

Check if you can access the temperature gradients first. My question: why are'nt you using the default Marangoni Stress Wall BC?