[Weiqiang Liu]

Hi all,

I am trying to assign different mass diffusion coefficients in different zones. I use DEFINE_DIFFUSIVITY.

In porous zone, mass diffusion coefficient is a combination of molecular and knudsen coefficient while in other fluid zone, mass diffusion is just molecular diffusion calculated by kinetic theory.

I attached my code here. I spend a while to check my code. However, it's still can not be loaded with some error. I think fluent only check syntax of the code no matter the logic is right or wrong.

Can anybody help me to check my code? I am very new to UDF.

Thanks very much!

Weiqiang

[CFD27]

Hello all,
I have a similar problem as Weiqiang Liu. I want to define two different diffusion coefficients in two different cell zones. For this I use the following UDF:

DEFINE_DIFFUSIVITY(diffusivity, c, t, i)
{
	Domain* d;
	Thread * tc1, * tc2;

	d = Get_Domain(1);
	
	tc1 = Lookup_Thread(d, 8);
	tc2 = Lookup_Thread(d, 9);


	if (t == tc1)
	{
		diffusivity = 1e-7;
	}
	else if (t == tc2)
	{
		diffusivity = 1e-5;
	}
	return diffusivity;
	
}

The UDF compiles without any problems. However, you can see in the post that the diffusion coefficients are not inserted correctly. Does anyone have an idea what this can be due to?
Many thanks in advance.
Many greetings
Joe

[juanfelipehincapie]

Did you finally figure out how to solve this problem? I'm trying to fix a diffusion value in a porous zone. I dont know how to do it.