Hey
Your geometry seems to be of trusses, For carrying out fea analysis(structural) , the geometry is suitable, and the mesh did not show any error because while carrying out FEA , the aspect ratio's of cells does not affect overall solution,but when it comes to CFD analysis, all of your geometry needs to be a single body,and the cells should be as uniform as possible.
these are the possible defects
1.) If you are making the geometry by creating different mates, make sure that there are no free spaces between the 2 parts.
2.) The mesh sizing are inappropriate, which means the min and max size of elements either have a huge difference, or it is simply not small enough to capture the details of the CAD model.
3.) If your CAD model have very fine details, for example if some curves are present and the surface thickness is very thin, then again it will create problems.
If you are planing to calculate forces induced in the geometry due to air flow or rain, then your current approach is NOT suitable at all as you have to create an enclosure for air flow.
I am an experienced user of ANSYS and have devoted all my time in learning the essentials of finite volume method. Any monkey can do CFD analysis by watching some youtube videos. But most of these "experts" won't be able to explain the theoretical part.
I hope it helped.