Hello everyone
The objective of my project is to study the dissolution of CO2 bubble in an oil in ANSYS Fluent using VOF model. For this, I am trying to implement a UDF for my mass transfer model (Bothe and Fleckenstein) but unable to do it because of some code errors. My problem statement has been attached in a file .
#include "udf.h"
DEFINE_MASS TRANSFER( CO2_dissolution, cell, thread, from_index, from_species_index, to_index, to_species_index)
{
float D, Cint,C,dist;
int n;
real X ,m_gl;
real cell_pos1 [3],cell_pos2 [3];
Thread *tf;
face_t f ;
X=7.6e-03;
D=8.02e-09;
Cint=8.183;
Thread *gas = THREAD_SUB_THREAD(thread, from_index);
Thread *liq = THREAD_SUB_THREAD(thread, to_index);
m_gl=0.;
begin_c_loop(cell, thread)
{
C_ CENTROID(pos1, cell, thread);
c_face_loop(cell, thread,n);
{
f = C_FACE(cell, thread, n);
tf = C_FACE_THREAD(cell ,thread, n);
F_CENTROID(pos2, f, tf);
}
dist=pow((pow((pos1[1]-pos2[1]),2)+pow((pos1[2]-pos2[2]),2)+pow((pos1[3]-pos2[3]),2)), 0.5);
m_gl= D* ((Cint - (C_VOF(cell,gas)*C_R(cell,liq)))/dist);
}
end_c_loop(cell, thread)
return(m_gl);
}
Desperately in search of an advice .
Hi,
Can you tell what kind of errors you are receiving? That makes it easier to check where the problem might originate from.
Also be aware that there is a macro for linearized mass transfer too, which is preferred in case your dissolution rate is related to flow variables.
Hello Cees Haringa , Thanks for your reply .
I haven't tried implementing it with Linearized mass transfer macro but the dissolution rate is obviously dependent on flow variables . So , here in my case when i initially tried running the Fluent in Parallel mode, there was a segmentation fault while initializing but then after switching to Serial mode, the Fluent surprisingly stops at a point and starts displaying the Parse errors in some lines of the code i.e in the lines where gas and liquid threads are being initialized .
All i wanted to know is whether using DEFINE_MASS_TRANSFER macro over LINEARIZED_MASS_TRANSFER does matter a lot this case and also is the syntax correctly reflecting the problem statement that i am upto ?
Segmentation faults are indicative of improper memory allocation. Did you properly set all the species and such before hooking the UDF?
Another issue is that FLUENT uses an older C implementation (C89 if I'm correct), where you first have to do all variable declarations before doing other things. So, I'd advise to declare the threads before assigning values to X, D and Cint.
I haven't used the linearized version myself yet, I just know from the manual it's advised to use that if possible.
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