## Fluids

#### How to call variable in solid domain to use in fluid domain?

Tagged:

• Imam Tantowi
Subscriber

Hello everyone,

Now, I am simulating a drying phenomena in cooling system. I model the grain using porous medium. because I want to know of solid porous, I set heat transfer in the porous medium as non-equilibrium. I also set UDS for moisture content of grain and humidity ratio in air. in solid zone, I want to calculate the moisture removal. But there is variable that solve in fluid domain that I want to use to calculate moisture removal. I think this problem can solved by using UDM. But, I dont know to transfer the UDM in fluid zone to using in solid zone. Does anyone know to solve this?

• DrAmine
Ansys Employee

What do you want to model in the solid zone? Moisture diffusion through solid?

• Imam Tantowi
Subscriber

Yes. I want to model moisture diffusion through solid. Actually, the main goal in my simulation is knowing temperatur and moisture characteristic in solid domain.

• Imam Tantowi
Subscriber

Yes. I want to model moisture diffusion through solid. Actually, the main goal in my simulation is knowing temperatur and moisture characteristic in solid domain.

• DrAmine
Ansys Employee

Okay so you need to solve UDS equations through solid zone.

• Imam Tantowi
Subscriber

Yes, DrAmine. I have done. Then, I want to model source term in my solid zone to model the moisture transfer from solid to fluid. but, for the calculation of source term, I need data on the ratio of humidity and air temperature which is in the fluid zone. I'm confused about how to call the variables in the fluid zone.

• Imam Tantowi
Subscriber

Assuming I'm using UDM, I think I can solve this by setting up the UDM in the solid zone and the UDM in the fluid zone for the same variable, for example variable X. I'll calculate variable X in the fluid zone and then I'll store it in UDM1. then there is a process where I will set the UDM2 value (which incidentally is for the solid zone) to be the same as the UDM1 value. I think so. However, I'm confused about how. is it possible to do something like that? do you use define adjust, define on demand, or something like that? how to give a pointer to the fluid zone and solid zone which can show that it is indeed data in the same cell?

• DrAmine
Ansys Employee

You need to calculate that ratio only in the fluid cells and the upper most in the near wall cells. There you calculate the amount which needs to be adsrobed or desorbed. That rate of flux / flow rate, can be used now at the solid wall side to provide a flux for the UDS / Boundary Value for UDS / Volumetric Source Rate.

Is not an easy step which I can comment on this open platform.

• DrAmine
Ansys Employee

The other way you are describing might require some low level function to transfer variable in one domain to another domain: dual cell appraoch. I am not sure if something like that is available on the customer portal.

• Imam Tantowi
Subscriber

Okey DrAmine, thank you for your answer. I will try what you suggested.

• DrAmine
Ansys Employee
Super.
• Imam Tantowi
Subscriber

Hello DrAmine, sorry I have one more question. In UDF fluent,Can I do looping in inner of other looping. let's say I write sample code below.
/*....*/

int zone1=1;
int zone2=2;
cell_t c1;
cell_t c2;
begin_c_loop(c1,t1)
{
...

begin_c_loop(c2,t2)
{

...

}
end_c_loop(c1,tuatas)
}
end_c_loop(c,tjatas)

/*.....*/

is it possible to do that?
• DrAmine
Ansys Employee

Nothing against that but it can be very expensive. Why do you need that?

• Imam Tantowi
Subscriber

I'm just thinking. Okay thanks for your answer. I think it can be used to transfer UDM value in one cell thread to another cell thread.