[ICEM] Two kinds of periodicity in one project

PS_KA · November 15, 2013, 03:49

Hello,

I would like to simulate a radial pump in 2D. For the meshing I am using ICEM-CFD 13.0.
I have got a rotor and a vaned diffuser. The rotor has got 6 blades and the diffuser has got 11 blades. So I have different pitch angles.
I would like to simulate just one blade of the rotor and one blade of the diffuser. I did two different meshs and merged them.
Now I have a problem with the periodicity. I know that I can set up periodicity in the global mesh parameters (Mesh/Global Mesh Setup/Set up Periodicity) and making the vertices periodic (Blocking/Edit Block/Periodic Vertices)

But when I am using the pitching angle of the rotor (60 degrees) the mesh of the diffuser is also periodic with 60 degrees and not 32.7 degrees (360/11). And also the other way around (32.7 degrees rotational periodicity).

So, how can I get two kinds of periodicity (60 degrees rotational periodicity for the rotor and 32.7 degrees rotational periodicity for the diffuser) in one project?

Many thanks in advance for your help.

Far · November 15, 2013, 04:22

you have to make two meshes. Export separately and import separately and make the interface there. That interface can sliding mesh, mixing plane or frozen rotor. So you have only one periodicity in one project.

myaccount · January 21, 2014, 01:38

Hi,
I want to simulate flow over inline arrangement of squares.Its a very big domain.So I want to chose a small domain and apply periodic boundary conditions.There will be a pressure drop in the flow.I want to specify mass flow rate at the inlet.
My question is if I apply periodic conditions,am I imposing fully developed conditions?If so, there will not be any variation in the velocity along the length(du/dy=0).But what I wanted was the variation in velocity along the small domain,which repeats in the big domain.where am I going wrong?
Any body, please clarify.

myaccount · January 22, 2014, 05:09

Hi,
How can we use same periodic conditions to
1.flow with a pressure drop,which is geometrically periodic in nature,and is not fully developed
and also to
2.Flow with a pressure drop,and fully developed flow(like fully developed flow through circular pipe)
Iam getting confused.Any body please clarify.

November 15, 2013, 03:49	Two kinds of periodicity in one project	#1
PS_KA New Member Join Date: Nov 2013 Posts: 1 Rep Power: 0	Hello, I would like to simulate a radial pump in 2D. For the meshing I am using ICEM-CFD 13.0. I have got a rotor and a vaned diffuser. The rotor has got 6 blades and the diffuser has got 11 blades. So I have different pitch angles. I would like to simulate just one blade of the rotor and one blade of the diffuser. I did two different meshs and merged them. Now I have a problem with the periodicity. I know that I can set up periodicity in the global mesh parameters (Mesh/Global Mesh Setup/Set up Periodicity) and making the vertices periodic (Blocking/Edit Block/Periodic Vertices) But when I am using the pitching angle of the rotor (60 degrees) the mesh of the diffuser is also periodic with 60 degrees and not 32.7 degrees (360/11). And also the other way around (32.7 degrees rotational periodicity). So, how can I get two kinds of periodicity (60 degrees rotational periodicity for the rotor and 32.7 degrees rotational periodicity for the diffuser) in one project? Many thanks in advance for your help.

January 21, 2014, 01:38	Concept of periodic conditions	#3
myaccount Member Join Date: Dec 2013 Posts: 53 Rep Power: 13	Hi, I want to simulate flow over inline arrangement of squares.Its a very big domain.So I want to chose a small domain and apply periodic boundary conditions.There will be a pressure drop in the flow.I want to specify mass flow rate at the inlet. My question is if I apply periodic conditions,am I imposing fully developed conditions?If so, there will not be any variation in the velocity along the length(du/dy=0).But what I wanted was the variation in velocity along the small domain,which repeats in the big domain.where am I going wrong? Any body, please clarify.

January 22, 2014, 05:09	Concept of periodic conditions	#4
myaccount Member Join Date: Dec 2013 Posts: 53 Rep Power: 13	Hi, How can we use same periodic conditions to 1.flow with a pressure drop,which is geometrically periodic in nature,and is not fully developed and also to 2.Flow with a pressure drop,and fully developed flow(like fully developed flow through circular pipe) Iam getting confused.Any body please clarify.

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November 15, 2013, 04:22		#2
Far Senior Member Sijal Join Date: Mar 2009 Location: Islamabad Posts: 4,558 Blog Entries: 6 Rep Power: 54	you have to make two meshes. Export separately and import separately and make the interface there. That interface can sliding mesh, mixing plane or frozen rotor. So you have only one periodicity in one project.