Ditch 3D-simulations

[brasp]

Dear,

I am simulating a ditch near an agricultural field. It is the first time that I am running a 3D-simulation and I encounter some problems. I designed a 3D-layered geometry and the upper layer represents my ditch at one side. Below the ditch, a seepage face BC was implemented to avoid fast saturation. However, I am not able to run the simulation which was probably related to the mesh structure. Can you please have a look to the design?

Thanks in advance!