[superkelle]

Hi I have following problem:


I have several inlets and those who do not align perfectly to my blockMesh are not getting meshed very well, especialy the edge. That is not so dramatic unless I apply a "flowRateInletVelocity" BC for the inlets. It applys a surface normal velocity based on the set flow rate. But because my edges of some inlets have hard cuts, I get a non uniform velocity at the inlets that are not perfectly alignd to the mesh. And so problems with Co, numerics etc. Does someone has an idea for a fix in the meshing?

[Lisandro Maders]

Hello!

I know there are ways to use blockMesh for not XYZ aligned geometries. However, why don't you use snappyHexMesh for that? I only use blockMesh for very very simple geometries. Yours I would go with snappyHexMesh without thinking twice!

Cheers

[superkelle]

Originally Posted by Lisandro Maders

Hello!

I know there are ways to use blockMesh for not XYZ aligned geometries. However, why don't you use snappyHexMesh for that? I only use blockMesh for very very simple geometries. Yours I would go with snappyHexMesh without thinking twice!

Cheers

It was created with shm

[Lisandro Maders]

it was late night, I completly misunderstood your problem...

Check your STL. Is the quality of it ok? Can you see some weird stuff on the affected mes regions in your STL geometry?

Also, try to extract the feature lines on those patches and apply a local line refinement to see if it helps.

[Yann]

Hello Alexander,


In addition to Lisandro's questions : what OpenFOAM version are you using ?


Yann

[superkelle]

Hi, I use OF7. The I checked the STL with surfaceCheck and the mesh after meshing with checkMesh. Both did not give any error. The whole geometry is very small, I thougt that this might be the problem. The height of the whole geometry is 2.7 cm and the diameter about 3 cm. One of the Inlets has a diameter of 0.1 cm. I also had to disable the maximum cellvolume in the meshquality dict.

Never the less I tried to make a finer backround mesh and addLayers (what I not really wanted because of the additional cells). It is now better, but still, all inlet patches that do not lay parallel to the backround mesh are somehow bad. The layers do not get created right, and they have again some corrupted cells at the edges. The attached pictures are from the same mesh.

[Lisandro Maders]

I think you meant minCellVolume in the quality check, right? Instead of disabling it, try to set it to 1e-18, since your geometry is really small.

I can see you have different levels of refinement in the surface. The layer addition struggles on these regions. Are you using different min/max levels of refinement for such surfaces? Like: levels (1 4)... If so, try to use same level or closer values to see if it helps, and not only for the inlet patches but for the connected-to-inlet wall patches as well

[superkelle]

Originally Posted by Lisandro Maders

I think you meant minCellVolume in the quality check, right? Instead of disabling it, try to set it to 1e-18, since your geometry is really small.

I can see you have different levels of refinement in the surface. The layer addition struggles on these regions. Are you using different min/max levels of refinement for such surfaces? Like: levels (1 4)... If so, try to use same level or closer values to see if it helps, and not only for the inlet patches but for the connected-to-inlet wall patches as well

Hi I tried those but nothing did really help, non the less thank you for your advise. But finaly I found a setting that works. But it is a little bit conta intuitive. I set other snapping control settings. I reduced nSmoothPatch to one, before it was seven. I don't know why that did the trick. Maybe it is a combination of this setting, mesh quality settings and the fact that the object is very small.

snapControls
{
    nSmoothPatch 1; //7
...
}