Learning Forum

[Joscha Hoppe]

Hello,

I attached a picture to understand the Problem better. I am trying to simulate a flow where the liquid is accelerated by a porous domain. I already did it with a momentum source term but i think there is also another option where i implement the velocity of the porous domain. It should be like moving mesh but without actually "running away" of the mesh. I hope you understand my Problem. 

I am thankfull for any advice.

Greetings

Joscha

[Rob]

Have a look at the reference frame options in Fluent - in the Cell Zone panel.  Are you also solving heat transfer? 

[Joscha Hoppe]

Hello Rob, 

thank you very much. No i am not solving heat transfer. It should simulate the flow of a Polymer resin through glass fibres which are pulled through the die from the left to the right side. What i expect is the resin after entering the porous domain flowing to the right exit.

I tried your advice with a steady simulation, but when i use moving reference frame the liquid is not really flowing to the right side. I attached some picture which i made after 100, 200, 300 and 700 Iterations. It is flowing in both directions. It is supposed to flow just to the right outlet. Did i do anything wrong?

If you have any other Ideas i would be very thankfull.

Greetings Joscha

[Rob]

OK. If there's no heat transfer you don't need to include the solid part: ie you can lose some of the mesh. 

What resistance coefficients are in the porous zone? For species mixture what is the diffusivity? The default is for gaseous systems so check if you're using liquids. 

 

[Joscha Hoppe]

Hey Rob,

For now i just use the default resistance coefficients for the porous zone (211100000 m^-2).I dont get exactly what you mean by diffusivity. I am pretty new to CFD Simulation, sorry for the basic question. I googled it and dont get it for 100%. Do I have to add a User-Defined Scalar for the transport of the fluid with the porous domain?

Again, thank you very much for your Input!

[Rob]

Look in the species mixture panel for diffusivity. Also, don't use the defaults for porous media, you need to put in suitable values for your system. 

There are some resources in the Help system (tutorials & examples) and lectures in the Learning section on here. 

[Joscha Hoppe]

Do you mean under Cell zone conditions like in the picture? I cant diffusivity there. Okay, i will use suitable values from the Literature!

[Rob]

Ah, you're using multiphase? That'll explain the lack of diffusivity. I think you need to review the physics in your real case and then how best to apply Fluent to solve that. 

[Joscha Hoppe]

Yes, sorry that i didnt tell you. It is air and the resin. I did a lot of research but couldnt find out how they implemented it in Ansys Fluent. The attached Paper is how i want to do it. My only Problem is to assign velocity to the porous domain. Like i said: With a momentum source term it already worked but this is not the way i want to simulate it. https://www.mdpi.com/2073-4360/14/4/666

Thank you rob, for your time.