[Robert Lang]

Hello everyone,


i want to simulate porous media with exceptionally high porosities in Flow3D-Hydro. I am using the Darcy-Forchheimer-Model to simulate the drag force of these porous media.


Whenever i set the porosity of the porous media to a value higher than 0.99 (less than 1% of volume blocked by the media), The simulation behaves as though the media does not exist and the results are pretty much the same as if i was simulating without any media.


Are there any limitations to the parameter "porosity"? I can not find anything in that regard in the documentation or in the forum.




With best regards,
Robert

[Robert Lang]

There is indeed a software limitation to the porosity setting. For anyone finding this thread:


The limitating variable 'EPS' limits volume fraction in the following way:
If the volume fraction is closer to 0 or 1 than the value of EPS, for example 0,009 or 0,991 with an EPS of 0,01 (default value) it just makes that volume fraction 0 or 1.


So if you want to simulate porosities closer to 0 or 1 you need to change the value EPS in the simulation settings (File -> Edit Simulation)




The confusing part of this was that in the documentation for porous media it states that if the porosity is closer to 0 than the value of eps, it sets it to 0. It does not say that the same is true for getting close to 1. That is only mentioned in the variable documentation of EPS which is kind of hard to find.