[jps115]

Hey everyone!

In a user-defined source term, I need access to the ln(mass_concentration) gradient. I tried to define a UDSI as the ln(density*massfrac). And then access the gradient of UDSI with C_UDSI_G(c,t,0). However, this seems to yield an error when iterating. I defined the UDSI as a define_adjust function and hooked it into fluent. Then I am trying to call the gradient of the UDSI in the defined_source function. Also good to note is that both functions compile without error and to make sure that I do not get the ln(x->0) = -inf, I add + 1e*-12 inside the ln function.

My question is if someone can help me obtain this gradient, I am not quite sure if my approach is the correct one and if so where it goes wrong. All help will be deeply appreciated.

[jps115]

It seems that the define_adjust function is the problem. To make sure I have access to the gradient I do use the text command /solve/set/expert and answer yes to “Keep temporary solver memory from being freed?”. I am not quite sure what seems to be the problem. Just as a reference I include the code below.

DEFINE_ADJUST(adjust_gradient, domain)
{
	Thread* t;
	cell_t c;
	face_t f;
	/* Fill UDS with the variable. */
	thread_loop_c(t, domain)
	{
		begin_c_loop(c, t)
		{
			C_UDSI(c, t, 0) = log(C_YI(c, t, 0) * C_R(c, t) + 1e-12);
		}
		end_c_loop(c, t)
	}
	thread_loop_f(t, domain)
	{
		if (THREAD_STORAGE(t, SV_UDS_I(0)) != NULL)
			begin_f_loop(f, t)
		{
			F_UDSI(f, t, 0) = log(F_YI(f, t, 0) * F_R(f, t) + 1e-12);
		}
		end_f_loop(f, t)
	}
}