Face and inflation sizing dependency on domain size
 

Hello,

I'm currently modelling a ducted fan beside a rectangular body in moderate proximity to the ground. I'm currently doing a domain independence study to determine the influence of the domain size on my results. Strangely, after a certain point, if I increase the domain size the surface mesh on the ducting starts to ignore my sizing rules, even though I haven't changed a single property other than the domain size. This leads to an unacceptably coarse mesh which prevents convergence.

Has anybody else experienced this, and if so, how did you fix it? I'm using ANSYS Meshing Version 16.2.

Thanks in advance!

post pictures and setup to make more sense

Here's a few pictures that should help. The overall domain is a quarter of a cylindrical section. I've found that by changing the sizing of the domain directly above the shroud that I was able to keep the same size mesh across the surface of the shroud. Strangely, I only encountered this problem at 1 grid density level. I didn't have the same problem at two other grid densities that have the same node size ratios for each region.

I think for now that I've been able to resolve this, although I admit I'm still not sure what the reason behind this problem is.