How to set directions for porous media ?
 

Hello,

I am modeling the flow of water around oyster tables. I've reduced the table to a simple parallelepiped : 7.20m long, 0.5m wide, 0.05m high. In situ, the tables are very thin, and pierced bags containing oysters are put upon them. Indeed, this very simplified geometry stands for the bags, and I neglect the legs of the table. Finally, the flow is colinear with the main size of the table.

The table can be modeled as porous zone, and I'm trying to find correct directions and coefficients for porous media. I have focused on C2 coefficients as the flow is mostly turbulent.

Regarding directions, the "obvious" configuration is :
- 2D : direction-1 : X=1 ; Y=0
- 3D : direction-1 : X=1 ; Y=0 ; Z=0
direction-2 : X=0 ; Y=1 ; Z=0
which is consistent with the orientation of the table itself.

Nevertheless, I have obtained better results (when compared to experimental data) with :
- 2D : direction-1 : X=1 ; Y=1
- 3D : direction-1 : X=1 ; Y=1 ; Z=0
direction-2 : X=1 ; Y=-1 ; Z=0
which is actually a 45° rotation compared to the first configuration.

Has anyone got an explanation for these results ? Has anyone encountered the same problem ?

Thank you very much for your answers !!!