[matthiass]

Hello everybody,

I'm new to OpenFOAM and I want to use CAD-Data meshed with Salome in OpenFOAM. For learning how to use OpenFOAM with structural mechanics I used a simple model. It is a simple beam, which is fixed at the bottom and displaced (0.04m in y-direction) at the upper part.

I tried the import (ideasUnvToFoam) of a hexahedral and a tetrahedral mesh with the complete same case. The hex-mesh worked fine and with the tet-mesh I get really strange results which I can't explain (see pics). checkMesh does not complain after the import of the tet-mesh.
Unfortunaley the mesh-size is to big, so i could not upload it.

I would be very thankful if someone could help me!

Best regards
Matthias

[matthiass]

Hello all,

is there anybody out there, who had a comparable problem or has anybody an idea where I can start searching.
I already checked my mesh with checkMesh and the solver converged as well.


Another question I have is:
one of my boundary conditions is a displacement of 0.04m:
oben
{
type fixedValue
value uniform (0 0.04 0)
}
Now I want that the motion in x- and z-direction is not "0" but changes, so that the boundary "oben" isn't anymore parallel to its initial position. Is there an easy way to do this?.

With best regards
Matthias

[Locky3827]

Hi,
I've had a similar issue in fluid dynamics in laminar pipe flow of non-Newtonian fluids. With hex meshes developed using blockMesh I get converged solutions which agree very well for the pressure drop with the analytical values. With tet meshes with viscous layers developed in Salome, the pressure drop is about 5% too high even though the solutions are well converged. I'm working through some possible issues with mesh quality and choice of discretisation schemes etc. Perhaps these will help. I want to move to more complex gemetries so I need to validate the meshing.
Not sure if I have helped, but perhaps there is an issue.
Regards,
Lachlan

[matthiass]

Hello Lachlan,

thank you for your reply! Until now I haven't found a solution for my problem. But I'm still working on it. As alternativity I'm testing snappyHexMesh, because I want to move to more complex geometries, too.

Best regards
Matthias

[kmooney]

Eric Patterson gives some good recommendations for discretization choices for unstructured grids in this Thread (post #5).

OpenFOAM - structured or unstructured Grids ?

It might improve your solution.

[matthiass]

Hi kmooney,

thank you for the link. It sounds interesting and I will try it!

Best regards
Matthias