I am trying to simulate a ceiling fan using the sliding mesh technique(geometry in pictures). The fan is of 24-inch dia and enclosure is 10*10*9 feet) I have tried many meshing techniques. Most of them give an error "mesh could not be generated with given input". meshing was successful using patch conforming tetrahedral but the minimum orthogonal quality is of the order of 10^-9 and maximum aspect ratio of 10^3. I am sure this is the reason for divergence error.
I have tried all the resolution of mesh and different element size, from total elements value of around 900000( min element size - 200 mm) to around 30000000 ( with min element size of 10 mm and 2 refinements at blades of fan in the rotational domain). there is a little change in the numbers of orthogonal quality and aspect ratio.
The geometry is pretty smooth and simple. don't think there should be any problem because of that.