[voldemort]

I am getting failed mesh (in the regions shown in attachment), the actual geometry is quite large (hidden to get a clearer view of the failed bodies).
The whole geometry consists of 92 bodies and these 2 are the only ones creating problem.
Meshing details:
To use solid 187, I chose a method with tetrahedrons and KEPT.
I applied the same to each and everybody simultaneously using Ctrl+A.

Other than this i am also getting quite a large no. of poor quality elements. What can be the possible reason for that.
And How to overcome this issue?

[Kapi]

you have to do some basic tutorials first.
Use of face sizing, edge sizing and body sizing will help.
Try to read about inflation and also which method is best suitable for your geometry.

[voldemort]

I went on to improve my meshing quality, but a couple of bodies always show mesh failure with the message,"The mesh faces on the following topological surfaces may intersect with mesh faces on other topological surfaces in the model, Please use different mesh size, virtual topology or correct CAD geometry."
How to solve this problem?

[Kapi]

refine those bodies further.
Use right sizing where you have bad elements.

Also check your geometry, are you importing it from CAD?
fill all the holes,remove unnecessary edges and make the geometry more simplified.
And use symmetry in your model if you can, no point running whole model

[voldemort]

Well yes, I imported them in form of CAD geometry in SAT format.
It turns out that I am specifying SOLID 187 by using tetrahedron method. But these couple of bodies, are meshed in triangular mesh (2D), when i cut a section i found it to be hollow (I cross checked again in CAD, it was solid).
The problem may be rectified if i am able to convert it to Solid again.
Please help me out here.

[Kapi]

use different format while importing
make sure you only import bodies

[divergence]

Refining the mesh size should help you out quite a bit. Are all of your volumes in one part? The volumes in the first figure seem to be non-conformal, which is of course quite ok if that's something you would want. Collecting every volume under one part might help you with the topological trouble. Did you try to use the "share topology" tool in DesignModeler yet? The tool might give you hint if there's something wrong with your model.

[ramkr]

Hey. M pretty sure you would have completed this problem by now. But my intent here is to just help new ones who'd get stuck similarly due to problematic geometry while creating mesh for CFD. So once I did face this problem in a large assembly with multiple parts in a wide range of sizes.The mesher successively failed although repair geometry could help solve problem in the Space Claim Geometry interface in ANSYS 18.1 by creating solid bodies from surfaces. I finally had to recreate the whole geometry as a proper solid part body with appropriate features (viz. extrude, revolve)on respective sketches instead of assembling.