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UDF for multiphase species transport (calculate the thread face temperature and press

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Old   February 24, 2020, 08:09
Post UDF for multiphase species transport (calculate the thread face temperature and press
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I have tried to write udf to adjust some values on a specific domain during the simulation of species transport in porous material using multiphase Eularian model, i have two phases; the primary phase (which is mixture water vapor and some gases), and the secondary phase (water liquid).
Below is my code used adjust function, the problem is i need to calculate species mass fraction density .....etc. and in the same loop i need to calculate the adjacent cell temperature and thread face temperature and pressure, i used the mp_thread_loop_f() and pointer for the primary phase to be able to loop the calculation over the primary phase. the problem is i cannot calculate the right thread face temperature and pressure, the code returned infinite value of face temperature as the solution converge. I cannot use F_T(f,tf) and F_P(f,tf) directly because the tf should be a pointer for the primary phase inside the mp_thread_loop_f() .
any suggestion to calculate the right face temperature and pressure in the same loop.

[PHP]DEFINE_ADJUST(temp_pressure_check, mixture_domain)
{
mixture_domain = Get_Domain(1);
Thread *tf = Lookup_Thread(mixture_domain, ID);

Thread *cell_thread; //cell thread in the
domain (in all the domain)//
Thread *tc;
cell_t c;
face_t f;
int phase_domain_index;
Domain *subdomain; // is for phase
Thread **pt;


mp_thread_loop_f(tf, mixture_domain, pt)

{
begin_f_loop(f,pt[0])
{
tc = THREAD_T1(pt[0]); // shadow cell thread

c = F_C1(f,pt[0]); // adjacent cell

Y_i= C_YI(c,tc,0);
wall_temp = F_T(f,tc); //*** problem: i need to
//calculate the F_T(f,tf) but i
//cannot use the the thread pointer

wall_press = F_P(f,tc) + operating_P;

............
}

end_f_loop(f,pt[0])
}
}
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Old   February 25, 2020, 07:32
Default Issues with the code
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1. You need to remove first line since Fluent is returning value for the mixture_domain. No need to use Get_Domain to fetch it

2. Fluent does not accept // for comment. You need to use /* */. Otherwise, it could lead to inexplicable errors.

3. ID is undefined

4. You are using wrong thread in the begin_f_loop {} end_f_loop. It has to be mesh thread, i.e., tf, and not pt[0]. With the loop, to access something, you have to either use tf or pt[0], depending upon whether data belongs to the phase or not. Such as, F_U belongs to phase but F_AREA does not.
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Old   February 25, 2020, 07:57
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thank you vinerm for your reply,

1. this part from my UDF, the ID defined in the other part.

2. i need to loop over the primary phase in the thread domain tf, the only way i found is to use the pointer to the primary phase in the begin_f_loop {} end_f_loop and this already mentioned in the ansys UDF manual, and itis works with i got reasonable results for the species mass fraction and density.
my problem is i cannot calculate the face temperature and pressure inside the same loop because i am looping over phase not over cells and walls.

saja
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Old   February 25, 2020, 08:09
Default Implications
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My point being, you should use tf in face loop and not pt. This way, you can access F_T and F_P as well as use F_YI or C_YI from pt. The reason is that pt is already available from the mp_thread_loop_f while the f for a particular tf becomes available only when begin_f_loop gets these two arguments. Look at the following

Code:
mp_thread_loop_c(t,domain,pt)
    if (FLUID_THREAD_P(t))
      {
	cell_t  c;
	begin_c_loop_int (c,t)
	  {
	    real c_vol = C_VOLUME(c,t);
            totvolume += c_vol;
	    if (C_VOF(c,pt[gp]) > 0.7)
	      {
		pvol += C_VOF(c,pt[gp])*c_vol;
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Old   February 25, 2020, 10:21
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thank you Vinerm,

I solved the problem by calculating the face temperature and pressure in another ADJUST function, and I saved the values in the UDMI, then used this values in the mp_thread_loop_f loop.
this way have worked with me and gave me a good results, but its costs me use two ADJUST functions in the same time for the same thread domain.

i will try your way and see whats gonna happen.

thank you
SAJA
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Old   February 25, 2020, 10:24
Default Good
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Nice to know that there is some solution that works.
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Old   March 2, 2020, 11:50
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Hello Vinerm,

i went back to your suggestion due to some problems in my codes, your suggestion is to use the statement: if (FLUID_THREAD_P(t)) to indicate the phase that i have, but this macro or function return true in case of the phase liquid, otherwise return solid phase.
in my case i have the primary phase (which is a mixture of some gases) and the secondary phase which is the water liquid. I need the pointer work on the primary phase (gas mixture), do you have any suggestion how to employ this if-statement to indicate to the mixture of gases under the: mp_thread_loop_f(t,domain,pt).

thank you
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Old   March 2, 2020, 11:58
Default Solid or Fluid
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The macro I shared is not meant for phase threads, rather for mesh threads to check if it is of type Fluid or type Solid. For phase thread, you simply fetch it's ID using DOMAIN_ID and compare if it is equal to the one given in Phases panel.

if(DOMAIN_ID(0) == 2)

Replace 2 with the number for gas phase from Phases panel.
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Old   March 5, 2020, 10:48
Smile Adjust function for multiphase species transport
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Hello Vinerm,

Thank you so much for your advice's, after struggling weeks in the loop, i have wrote an adjust function can calculate the face temperature, cell temperature and pressure, cell mass fraction (for the primary phase)and density for multiphase species transport, and here is my loop:

DEFINE_ADJUST(calculate_Var, mixture_domain)
{


mixture_domain = Get_Domain(1);
Thread *tf = Lookup_Thread(mixture_domain, ID);
Thread *cell_thread;
Thread *tc;
cell_t c;
face_t f;
Thread **pt;
Thread *ti;

mp_thread_loop_f(tf, mixture_domain, pt)

if (DOMAIN_ID(tf) == 2)

{
begin_f_loop(f,tf)
{
tc = THREAD_T0(tf); /*adjacent cell thread*/
c = F_C0(f,tf); /*adjacent cell*/

pt = THREAD_SUB_THREADS(tc);

ti = pt[0]; /* pointer for the primary phase*/

Y_i= C_YI(c,ti,0);

rho_g = C_R(c,tc);

wall_temp = F_T(f,tf);

wall_press = F_P(f,tf) + operating_P;

cell_temp = C_T(c,ti);

cell_press = C_P(c,ti) + operating_P;

}

end_f_loop(f,tf)
}
}


Thank you
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Old   March 5, 2020, 10:53
Default Good
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That's good, Saja.

First line is not needed since Fluent already provides the value of mixture_domain. Do note that in every DEFINE_ function, Fluent only expects names of variables, not their values. Fluent provides their values to be used in the code.
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Old   March 5, 2020, 11:01
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thank you,
i will remove the first line,
thank you so much for your helping and time
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