[jasimpson89]

Hi, I am very new to CFD and the use of open foam.


I would like to be able to create a hex mesh over the whole bounding box of a geometry using blockMesh and then to go and remove all cells the lie outside the geometry.* The reason being is that I have a complex geometry that is difficult to block and can live with the CFD geometry being a stair-stepped approximation of the real geometry.* I want to automate the process so don't want to rely on a 3rd party mesher or snappyHexMesh * Has anyone done something similar?*

Currently I am using a very simple geometry of one block and a 3x1x1 cell configuration just to see a method of how I could automate this. So I have 3 cells adjacent to each other (012). What I am trying to do is delete cell 1 the middle cell of this system.

The procedure I am following is:

1. Editing the boundary file, subtracting off 2 faces because I have removed four faces but two of the internal faces have no become boundary faces. And setting the start to 0 (no more internal faces)

2. Editing the faces file to reflect the changed I have made of deleting the faces

3. Setting the neighbour file 0( ) as we have no neighbours now?

4. Deleting the in the owners file the owner associated with the faces I have deleted.

After all this is done when I open this in paraFoam, the internal mesh I am given is just weird it doesn't seem to reflect the changes I have made, Sometimes faces are missing and point join up in weird ways making weird and wonderful shapes.

Two things to note are:

1. All these changes are made after the command blockMesh is ran

2. I ran checkMesh on my edited geometry and obviously it crashed. However I did notice that it was expecting there to be 9 cells present, but I want 8 because I am trying to delete one. One would assume that paraFoam would be expecting 9 and not 8 so hence my weird shapes. But I don't know what file to edit to change the number of cells in my geometry. Does anyone know? or does checkMesh work it out from your blockMeshDict?

Apologies if anything I have mentioned is confusing I would be more than happy to clarify any of the points I have made.

Thanks in advance

James