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-   -   Sliding mesh model problem (http://www.cfd-online.com/Forums/fluent/46879-sliding-mesh-model-problem.html)

Usman December 21, 2007 07:15

Sliding mesh model problem
 
Hi,

I am trying to model 3D stator/rotor geometry using periodicity. - How can I make the periodic angle of the mesh around the stator blades to be the same as that of the mesh around the rotor blades. I have 36 stator and 54 rotor blades. - Can the periodic boundaries be non-planar.

Many Thanks for help,

al_c December 24, 2007 05:38

Re: Sliding mesh model problem
 
"How can I make the periodic angle of the mesh around the stator blades to be the same as that of the mesh around the rotor blades. I have 36 stator and 54 rotor blades."

Periodic angle can be equal to 20 degrees (1/18 part of full domain). In this case periodic domain will contain two stator blades and three rotor blades.

"Can the periodic boundaries be non-planar"

Yes, they can be non-planar.

Usman December 24, 2007 12:32

Re: Sliding mesh model problem
 
Hi, Thank you. Can i not model a single passage with sliding mesh model that is, one stator blade and one rotor blade. (i have 36 stators and 54 rotors), Thank you.

al_c December 24, 2007 16:10

Re: Sliding mesh model problem
 
For sliding mesh model the periodic angle for stator must be the same as for rotor. 20 degrees is the minimal angle that is periodic for both regions - for rotor and stator. Therefore you can't model one stator blade and one rotor blade for your task.

usman December 25, 2007 13:50

Re: Sliding mesh model problem
 
Dear Friend, Thank you very much for your help. Is the condition of minimal angle of 20 degrees mentioned in Fluent documentation. Many thanks again.

al_c December 25, 2007 17:07

Re: Sliding mesh model problem
 
Minimal angle is dependent from the number of stator and rotor blades. You have 36 stator and 54 rotor blades. Minimal periodic angle for your stator is 360/36=10 degrees. Other periodic angles for stator are ns*360/36 degrees. Where ns is the number of blade passages for stator. Minimal angle for rotor is 360/54=6.67 degrees. Other periodic angles for rotor are nr*360/54 degrees, where nr is the number of blade passages for rotor. For sliding mesh model the periodic angle for stator must be the same as for rotor (for possibility to create periodic grid interface). This condition is satisfied with ns=2 and nr=3. Therefore we have 2*360/36=3*360/54=20 degrees for minimal periodic angle.

usman December 25, 2007 18:57

Re: Sliding mesh model problem
 
Dear Friend, Many Thanks, I am very grateful and obliged for your kind help.

usman January 12, 2008 17:18

Re: Sliding mesh model problem
 
Dear Friend, Hello, I am having difficulty in making periodic faces around 2 stator blades. should i make one periodic face and then rotate to 20 degrees. should the periodic face be between any two blades.

Thank you.

saha2122 May 18, 2013 01:44

Hi

i have a question...

i wanna solve a steady 3D problem.... may I use slidding mesh? in the other hand isnt the sidding mesh just for transient problems?

TX.

Goodstuff January 30, 2015 06:37

Hi,

Do all the aforementioned remarks hold true for a 2-d sliding mesh stator-rotor-stator simulations? I mean, do I HAVE to create periodic zones, which are characterized by the same periodical translation vector? Naturally, I have different count of blades/vanes, but the ratio is not as pleasant (38/34/38). Moreover: do the element sizes on both sides of the interface must be equal or match one-for-one?


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