Multiphase FSI coupling

Hi all,
I’m currently doing FSI coupling adopting our in-house solver (solid part) and openfoam (fluid part). However, there is a question that’s been bothering me:

The case I want to simulate includes a porous media baffle, with water on the left side and no water on the right. I want to simulate the process that water on the left flows into the porous media and then flows into the right side.

In my simulatioin, the seepage velocity (from the soil to the fluid domain) at the interface is calculated by solid part. Then, there should be more water at the interface in fluid domain. I’ve managed to couple the seepage velocity on the interface in OF, but how could I add the water due to the seepage according to the velocity at the interface? Could anyone please give me any hints?

Thanks in advance!

Currently I’m trying to use flowRateInletVelocity boundary at the interface to add more water into the fluid domain. However, this BC seems to give the velocity on the boundary based on a constant mass or volumetric flow rate instead of giving the volumetric flow rate according to the velocity of cells at the interface. Is there anyone familiar with this boundary condition or have any hints?
I guess it is similar to the process of making waves since there is more water due to the velocity on the wave generation boundary. However, I don’t know the specific practice, could anyone please share some of your experience if you don’t mind.

I don’t know anything about this or similar boundary conditions. However, one trick you could try would be to manually compute and couple the alpha field to signify where there is water. This is the approach described in Francisco Espinosa’s Master’s thesis: mediaTUM - Media and Publication Server

Hi @Makis ,
Thanks for your reply!

Up to now, my senior fellow apprentice and I found that once the velocity of a specific boundary is passed to OF, the water phase is changed automatically. The following picture shows the water phase change in the coupling simulation using preCICE, even though the result is not right here (The water level is supposed to go down at the left side).

This wrong result may be related to some mistakes, whether error implementation of seepage velocity in our solid solver or anything wrong during the mapping. By the way, I reckon that your advice of coupling the alpha field may be a good choice and I’ll have a look, thanks!

It looks like you forgot to upload the picture :see_no_evil:

Oh, sorry for that!
The initial state and the final water level are uploaded now even though the final water level on the left side is wrong: