[schwaral]

Hi all,

Instead of using the default flux term I want to use my own flux term now. I want to modify the velocity later and so on...

Now I started testing the DEFINE_UDS_FLUX example and I noticed, that for velocity =0 at the beginning of my Inlet-Velocity-SIgnal the example ends in wrong results.

I use a simple 1D case with 10 cells. left-side is UDS-Inlet with UDS-specified-Value=0.02939, right side is UDS-Outlet with Flux=0. in The middle of Domain I have 2 Cells with a source for UDS. I notice weird behavior on the left side at Inlet for velocity in my domain =0. The UDS Value is becoming too large then. I do not know how to avoid this, but I cannot negelect this behavior.

The code from User Guide:

DEFINE_UDS_FLUX(my_uds2_flux, f, t, i) //RETURNS MASS FLOW RATE THROUGH A GIVEN FACES
{
	cell_t  c0, c1 = -1; //the cell thread index
	Thread* t0, * t1 = NULL;
	real NV_VEC(psi_vec), NV_VEC(A), flux = 0.0;

	c0 = F_C0(f, t);
	t0 = F_C0_THREAD(f, t);
	F_AREA(A, f, t);

	/* If face lies at domain boundary, use face values; */
	/* If face lies IN the domain, use average of adjacent cells. */

	if (BOUNDARY_FACE_THREAD_P(t)) /*Most face values will be available*/
	{
		real dens;

		/* Depending on its BC, density may not be set on face thread*/
		if (NNULLP(THREAD_STORAGE(t, SV_DENSITY)))
			dens = F_R(f, t);   /* Set dens to face value if available */
		else
			dens = C_R(c0, t0); /* else, set dens to cell value */


		NV_DS(psi_vec, =, F_U(f, t), F_V(f, t), F_W(f, t), *, dens); // F_U(f, t) = u_velocity at face

		flux = NV_DOT(psi_vec, A); /* flux through Face */
		Message0("1: %g\n", flux);
	}
	else
	{
		c1 = F_C1(f, t);       /* Get cell on other side of face */
		t1 = F_C1_THREAD(f, t);

		NV_DS(psi_vec, =, C_U(c0, t0), C_V(c0, t0), C_W(c0, t0), *, C_R(c0, t0));
		NV_DS(psi_vec, +=, C_U(c1, t1), C_V(c1, t1), C_W(c1, t1), *, C_R(c1, t1));

		flux = NV_DOT(psi_vec, A) / 2.0; /* Average flux through face */
		Message0("2: %g\n", flux);
	}

	/* ANSYS FLUENT will multiply the returned value by phi_f (the scalar's
	   value at the face) to get the "complete'' advective term.  */

	return flux;
}

[schwaral]

It seems like the 3D case works just fine but 1D is not correct after initialization. It has to be something with the code or missing information from initialization. But I initialize in the same way I do with 3d.

[sacespedeszu]

Hi schwaral. I am facing the same problem in 3D. The UDS_FLUX Example gives me wrong results. Have you managed to solve that problem?