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colinB September 17, 2010 04:17

basic understanding of sHM
Hi guys,
after working with sHM for a while and didn't get the results that I needed I have to ask you some questions, to get a better basic understanding.

The case I'm working on is comparatively simple.
To simulate the flow of water around a floating structure and get the resulting wave pattern I want to use interFoam.
The geometry of the solid that shall be examined I have as an .stl file and stored in a trisurface folder.
And finally the background mesh is created with blockMesh (simple box with elements of an aspect ratio close to one).
Everything is done according to the guidelines of
So now it comes to the snappyHexMeshDict file where I don't get every parameter, even after reading the manual more than twice.
The questions that arose:

Which is the parameter that defines the location of the stl geometry in the background mesh?
I know there is a parameter called location in mesh, but what exactly is his function and where is the point he is located in the stl file (if this is the right parameter for that issue)

How do I have to understand the splitting parameter?
There is a level specification, but can I assume that level 1 splits one element in 8 sub elements level 2 in 64 and so on?

What has the parameter locationInMesh with the cell removal to do?

I hope these questions are not too basic

thanks for your trouble


Edit: I got the snappyHexMesh comand running without any errors but viewing the mesh with paraFoam I couldn't find my floating structure within that mesh.

colinB October 6, 2010 08:17

for those of you who have the same questions like me,
I could answer some of them and I want to share. I know
that some things might look trivial especially when you have
been working with sHM for some time, but though these
answers might help the one or other user to get little easier into sHM.

How do I locate a stl geometry in my background mesh
generated with blockMesh:

Both meshes have a (0 0 0) coordinate and these will be
on top of each other when combined in the sHM mesh.

How can I view the total mesh after running sHM and
how is the calculation done with the sHM Mesh and
not just with the background mesh:

always use the command: snappyHexMesh -overwrite
and not just snappyHexMesh. This will overwrite the mesh
information in the relevant folders and you can see/calculate
now with the mesh generated by sHM

What is the parameter locationInMesh for:

place this point in the part of the Mesh you want to keep
(I know it is explained very well in the documentation)

so far my cognition
regards Colin

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