[Bruno Machado]

Hello guys,

I will explain my problem first and subsequently ask you a question. I have 2 fluid zones, called zone 1 and 2. At the zone 1, I am solving the UDS-0. Nevertheless, this UDS-0 is not solved at the zone 2. The problem I face is that the one of my energy source terms (ohmic heating) considers the gradient of UDS-0 in its calculation. So at the interface, Fluent picks the value of UDS-0 at the cell in zone 1 and solves the gradient to the cell in zone 2 (which is 0 since this UDS is not solved there). Thus, it ends up giving me a value that has no physical meaning, leading to extremely high temperatures.

I wrote this piece of code to define the gradient at the interface as 0 and solve it everywhere else as it should be.

DEFINE_EXECUTE_AT_END(gradient_zero_boundary)
{
Domain *d;
face_t f;
cell_t c, c0, c1;
Thread *t, *t0, *ct, *t1; 
d = Get_Domain(1);


/* Initialise Cells */
thread_loop_c(ct, d)
{
	begin_c_loop(c,ct)
	{
		C_UDMI(c,ct,SOLID_PHASE_CURRENT_DENSITY_X) = C_UDSI_G(c,ct,ELEC_POT)[0];
		C_UDMI(c,ct,SOLID_PHASE_CURRENT_DENSITY_Y) = C_UDSI_G(c,ct,ELEC_POT)[1];
		C_UDMI(c,ct,SOLID_PHASE_CURRENT_DENSITY_Z) = C_UDSI_G(c,ct,ELEC_POT)[2];
	}
	end_c_loop(c,ct)
}

/* Loop over all faces on wall */

t = Lookup_Thread(d,33);
	
	begin_f_loop(f,t)
	{
	c0 = F_C0(f, t);
	t0 = THREAD_T0(t);
	
		C_UDMI(c0,t0,SOLID_PHASE_CURRENT_DENSITY_X) = 0.0;
		C_UDMI(c0,t0,SOLID_PHASE_CURRENT_DENSITY_Y) = 0.0;
		C_UDMI(c0,t0,SOLID_PHASE_CURRENT_DENSITY_Z) = 0.0;
	}
	end_f_loop(f,t)

	
t = Lookup_Thread(d,34);

	begin_f_loop(f,t)
	{
	c1 = F_C1(f,t);
	t1 = THREAD_T1(t);
	
		C_UDMI(c1,t1,SOLID_PHASE_CURRENT_DENSITY_X) = 0.0;
		C_UDMI(c1,t1,SOLID_PHASE_CURRENT_DENSITY_Y) = 0.0;
		C_UDMI(c1,t1,SOLID_PHASE_CURRENT_DENSITY_Z) = 0.0;
}
end_f_loop(f,t)
}

The problem is that since it is 2 fluid zones, there is no boundary condition between them (even after naming the surface of interest - remains as interior). Here comes my question. How can I identify the cells at the interface to define them as 0? In this piece of code, I tried to give the thread value of the zone, but it did not work. Any suggestions?

Thank you in advance for any helpful comment.

[Bruno Machado]

Well, I found one way of doing it. The code works fine. Just had to name the interface I wanted to define the variable as 0 and input its ID in the code before provided.

I contacted Ansys in the past and they said this is a bug and they would correct it for the new versions. not sure they did it on 16/17 versions.