I have a truck (volume) model which i subtracted from a brick as the ambient domain. After meshing the surface of the truck with 'submap' and 'pave' i tried to mesh the whole volume, but neither 'hexa' nor 'tetra' option works. Can anybody make a proposal how i could handle this problem. Thanks in advance

U r probably meshing using gambit, personally I believe that gambit is not good at all for meshing, however, I recommend you to break ur big domain into several small domains and the wall between these domains call it "interior", the process of meshing this way takes longer but it is easier to mesh.

hope this help

Thanks a lot. I am gonna try it that way... Should i keep the whole geometry connected while splitting or is it better to create independent blocks?

I guess u should make new independent blocks, but the interior boundary condition needs common face for connecting volume/block.