[Per_Holmgren]

Hi!

I'm trying to write a udf where the mass flux of the secondary phase at the face with id=7 is used as the mass flux in the boundary where I use the udf.

DEFINE_PROFILE(inlet_mass_flow,t,i)
{
real mass_in = 0;
real mass_tot = 138.30072;

int phase_domain_index = 1; /* secondary phase index is 1 */
Domain *mixture_domain;
Domain *subdomain = DOMAIN_SUB_DOMAIN(mixture_domain,phase_domain_inde x);

Thread *mixture_thread; /* mixture-level thread pointer */
Thread *subthread = THREAD_SUB_THREAD(mixture_thread,phase_domain_inde x);

face_t f;

subthread = Lookup_Thread(subdomain, 7);

mass_in = F_FLUX(f,subthread);

mass_tot = mass_in;
mass_in = 0;

begin_f_loop(f,t)
{
F_PROFILE(f,t,i) = mass_tot;
}
end_f_loop(f,t)
}

This lead to an immediate crash when I click ok. Can anyone give me some pointers?

[Per_Holmgren]

In case anyone else comes across this post, I figure I might as well post the code I came up with to solve my problem.

In my case CaCO3 enters a reactor, converts to CaO and CO2, and CaO and CaCO3 leaves at the outlet at a set volume per second (specified as a negative velocity profile in a different udf).
Based on the mass flow of solids out, and the degree of conversion, I need to refill the reactor with an equal amount of CaCO3 to match the amount of CaCO3 and CaO that leaves at the solids outlet.


DEFINE_PROFILE(adjust_inlet, t, i)
{
face_t f;
real massflow=0;
real massflow_tot=130;
real massfraction_CaCO3=0;
Domain *d;
Domain *d_sub;
Thread *t_sub;

d = Get_Domain(1);
d_sub = DOMAIN_SUB_DOMAIN(d,1); /*Find secondary phase*/
t_sub = Lookup_Thread(d_sub, 7); /*Find thread on secondary domain with id 7*/

begin_f_loop(f,t_sub) /*Loop through all face threads on domain with id 7*/
{
massflow+=F_FLUX(f,t_sub); /* Assign mass flux at given face to variable massflow for each face thread*/
massfraction_CaCO3=F_YI(f,t_sub,2); /* Find mass fraction of specie 3(CaCO3 here)to normalize massflow later*/
}
end_f_loop(f,t_sub)

massflow = PRF_GRSUM1(massflow); /*Sums the values of the cores into a single value*/
massfraction_CaCO3 = PRF_GRSUM1(massfraction_CaCO3);
massflow_tot = (massflow*((100.09/56.08)-((100.09/56.08)-1)*massfraction_CaCO3))*2*M_PI; /*Corrects for 2D-axisymmetric profile*/
massflow=0;

begin_f_loop(f,t)
{
F_PROFILE(f,t,i) = massflow_tot; /*Inserts flow for 2D-axisymmetric profile*/
}
end_f_loop(f,t)
}

As I use parallel processing I need to use PRF_GRSUM1 to get my eight values of for example massflow into a single value, and to be able to compile PRF_GRSUM1 you need to start fluent from the Visual Basic command prompt.

Compile Fluent UDF with Windows 10

I was stuck at the compiler issue for a pretty long time, since I didn't understand that fluent actually couldn't find the compiler. I thought my code was wrong!