I believe i have stumbled upon the answer to the volume question, although i wasnt attempting to solve it.
I was trying to do some quick meshing to see the effects of different boundy layer settings (i want to have a good representation of the Y+ value between 30 and 300) and i used the merging script provided by simscale as this saves a lot of time. The merging script just throws all the STLs together but creates a 3D object file as the output shown below.
Normally i merge everything by hand in notepad so all files are saved as TXT files, which i believe converts the face selections to solid bodies. This is shown in the next picture where i merged everything manually and the drop down menu for each entity in the tree is now gone.
This can be seen under the highlighted MRF zone in the picture. This object is recognized as three faces, which, when combined are classified as a volume. This is shown in the next picture.
The MRF zone is now classified as a volume. In the next picture, it is shown with tire removed, that these three faces are:
- the front side of the cylinder in red
- the depth of the MRF cylinder in blue
- (Not shown) the other side of the cylinder
these three faces when selected together create the volume that is needed to have a functioning MRF zone (so i hope)
I will be doing a simple mesh now to confirm this.
Hope this helps