I would like to model the 3D flows around obstacles (see attached fig.) within a box. But I cannot produce a proper 3D mesh (only 2D mesh can be produced on the surface of the box) within the box, though I press the "3D" buttom. And I can only obtain the surface results only.
Re: Cannot produce a 3D mesh within the model domain
I'm quite sure you have just misunderstood how to use the software. The "surface" plot will only show you the solution on the outer surfaces of your model, if you wish to plot/view the interior then select another plot type such as iso surface plot or slice plot. I would also recommend trying to follow any of the 3D tutorials so you get a feel for how the software works, for example: