How could I named too many surfaces as wall?
 

Hi everybody,

I Imported a Part consist of the 3 bodies into DM in ansys workbench 14.5 for meshing and doing fluid analysis in fluent. my geometry consists of too many complex surfaces inside which I want them to be considered as wall except for 3 of them.
My question is that as I import my geometry into design modeler there is no surface shown in the tree, so how can I select them and named them? should I select them by hand? they are too much around 500 surfaces.

I really appreciate your help.

Thanks