gap between rotor and stator domains

Red Ember · October 21, 2016, 06:35

Hi to all!

Trying to simulate axial compressor, I get little gap between domains.
I have to create one part between rotor and stator using meshing while rotor and stator domains meshes are done via turbogrid.
But inlet/outlet borders in TG have little differences from desired. Changing A and R coordinates I cannot assign accurate values.
Ex.: R2 Inlet: (1725;170.850679) for hub changes into (1725;170.839) automatically. This border is not vertical if it does matter.
So, I get few microns wide gap, although results in CFX-Post seem to be acceptable as if there's not any gap.
Is there any tolerance values for such gaps? Or is it not a problem at all?

ghorrocks · October 21, 2016, 06:37

GGI interfaces can handle small gaps. Have a look at the overlap % to see if you have any unexpected regions which have not matched up.

Red Ember · October 24, 2016, 02:21

Quote:

Originally Posted by ghorrocks

GGI interfaces can handle small gaps. Have a look at the overlap % to see if you have any unexpected regions which have not matched up.

thanks for answer
1. how can I determine whether this gap is small enough to be handled or not?
2. and how can I see this overlapping? Do you mean solver .out file?
I've found overlap and non-overlap mentioning but what do these numbers mean? Is there somrthing bad?

"Domain Interface Name : S1 cav1
Discretization type = GGI
Intersection type = Direct
Non-overlap area fraction on side 1 = 4.05E-01
Non-overlap area fraction on side 2 = 7.07E-02"

" Interpolating Onto Domain "cav1"
Searching for Candidate Source Domains:
Domain "S1"
Number of Mapped Nodes = 24911 ( 8.8%)
Bounding Box Overlap Volume = 2.35554E-04 ( 29.0%)
Setting Up Unmapped Nodes:
Number of Unmapped Nodes = 257581 ( 91.2%)"

October 21, 2016, 06:35	gap between rotor and stator domains	#1
Red Ember Member Alex Join Date: Feb 2016 Posts: 81 Rep Power: 10	Hi to all! Trying to simulate axial compressor, I get little gap between domains. I have to create one part between rotor and stator using meshing while rotor and stator domains meshes are done via turbogrid. But inlet/outlet borders in TG have little differences from desired. Changing A and R coordinates I cannot assign accurate values. Ex.: R2 Inlet: (1725;170.850679) for hub changes into (1725;170.839) automatically. This border is not vertical if it does matter. So, I get few microns wide gap, although results in CFX-Post seem to be acceptable as if there's not any gap. Is there any tolerance values for such gaps? Or is it not a problem at all?

October 21, 2016, 06:37		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	GGI interfaces can handle small gaps. Have a look at the overlap % to see if you have any unexpected regions which have not matched up. Red Ember likes this.