1. how to write mesh from prostar

Type ngeom,[name].ngeom,star in the command line. This will create a
.ngeom file of your Prostar model.

If you have boundaries defined, these will be kept in the .ngeom file so
you won't have to rename and redefine the boundaries in ccm+. However,
the values (properties) are not exported.

If you don't have boundaries you'll get a single wall patch in ccm+ that
you'll have to split accordingly.

2. how to load it into star-ccm+

In ccm+ create a new simulation and do File>Import...

Browse to the location where you have your .ngeom file, select it, press
OK and that's it.

3. how to do merging (or is automatic?)

If you had couples in your Prostar model, your meshes will all be
"fused" together automatically in ccm+ when you import the .ngeom file.
Keep a look on the output window in Prostar when you run the ngeom
command to make sure the couples are exported OK.

Alternatively, you can "fuse" the different fluid regions in ccm+. To do
this select all the fluid regions you want to merge together from the
command tree on the left of your screen, under Regions. Press control
and click on top of each one, once you've selected all, click the
right-hand buttom of your mouse and select Fuse...

4. how to save it from star-ccm+

Once your model is ready in ccm+ (i.e. all regions and boundary patches
defined), go to File>Export... and select .ccm format.