# modify cyclic b.c.

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 May 8, 2012, 09:08 modify cyclic b.c. #1 New Member   Adrian Zenklusen Join Date: May 2012 Posts: 2 Rep Power: 0 Sponsored Links I'm simulating the spreading of a contaminant from a point source in a fully developed duct flow. So I would like to apply the cyclic boundary conditions (with the channelFoam solver) for velocities and pressure but not for the concentration of the contaminant (once the contaminant is at the outlet, it should not be feed in at the inlet) So far I used directMapped (map velocities and pressure of the cross section in the middle to the inlet) at the inlet and zeroGradient at the outlet for pressure and velocities. For the contaminant concentration I used zeroGradient at the outlet and fixedValue (=0) at the inlet. So my duct is actually longer than I need (the influence of the zeroGradient boundary condition at the outlet requires that the duct is long enough). I'm wondering, if it's possible to use cyclic boundary conditions for pressure and velocities but not for the contaminants concetration. Acutally I want to set the concentration to 0 at the inlet. Could someone tell me which files I have to modify?

June 4, 2012, 12:44
#2
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Jian Zhong
Join Date: Feb 2012
Location: Birmingham
Posts: 109
Rep Power: 7
I also met the same problem. Did you solve it? If so, could you please tell me how to do that?

Quote:
 Originally Posted by Adrian83 I'm simulating the spreading of a contaminant from a point source in a fully developed duct flow. So I would like to apply the cyclic boundary conditions (with the channelFoam solver) for velocities and pressure but not for the concentration of the contaminant (once the contaminant is at the outlet, it should not be feed in at the inlet) So far I used directMapped (map velocities and pressure of the cross section in the middle to the inlet) at the inlet and zeroGradient at the outlet for pressure and velocities. For the contaminant concentration I used zeroGradient at the outlet and fixedValue (=0) at the inlet. So my duct is actually longer than I need (the influence of the zeroGradient boundary condition at the outlet requires that the duct is long enough). I'm wondering, if it's possible to use cyclic boundary conditions for pressure and velocities but not for the contaminants concetration. Acutally I want to set the concentration to 0 at the inlet. Could someone tell me which files I have to modify?

 June 6, 2012, 06:33 #3 New Member   Adrian Zenklusen Join Date: May 2012 Posts: 2 Rep Power: 0 Unfortunately not. I tried to modify fvScalarMatrix, but with no success.

July 2, 2012, 11:39
#4
Senior Member

Jian Zhong
Join Date: Feb 2012
Location: Birmingham
Posts: 109
Rep Power: 7
Quote:
 Originally Posted by Adrian83 So far I used directMapped (map velocities and pressure of the cross section in the middle to the inlet) at the inlet and zeroGradient at the outlet for pressure and velocities. Could someone tell me which files I have to modify?
Hi, can you use 'directMaped' BC for cyclic inlet and outlet patches?

My best regards,
Jian

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