# Weird hydraulic jump with interFoam [SST k-omega]

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 May 7, 2013, 23:23 Weird hydraulic jump with interFoam [SST k-omega] #1 Member   David Long Join Date: May 2012 Location: Germany Posts: 45 Rep Power: 3 Hi Foamers, I want to simulate free surface flow (or stream flow) around cylinder. Now RAS model SST k-omega is used. [v=2m/s at +x direction, the water level is set to h=0.6m using groovyBC] It seems that the results looks reasonable (see Fig above), however, the hydraulic jump at the front of Cylinder looks weird, while the flow is more or less "dynamically stable". Is it because the inlet is too close to the Obstacle - cylinder? I checked the BCs but could not figure this out, is there some wrong the BCs with inlet? Best David wes1204 likes this. Last edited by keepfit; May 10, 2013 at 01:01.

 May 8, 2013, 03:39 #2 Senior Member   Pablo Higuera Join Date: Jan 2011 Posts: 133 Rep Power: 4 Hi David, you are specifying 2 conditions for the flow: level and velocity. Your level is increasing due to the presence of the obstacle, but GroovyBC does not allow the flow to reach the boundary (see how there is no water above your given level for the cells adjacent to the inlet). Depending on what was your goal, taking the inlet far away enough from the cylinder may solve your problem, if you want to prescribe both level and velocity. If what you need to impose is only a discharge (velocity) I guess you should leave alpha1 as zeroGradient and code a BC to calculate the wet area and apply the calculated velocity to such area. In this case you most probably can reach a stable state with your current domain. Best, Pablo ngj likes this.

May 8, 2013, 07:09
#3
Member

David Long
Join Date: May 2012
Location: Germany
Posts: 45
Rep Power: 3
Quote:
 Originally Posted by Phicau Hi David, you are specifying 2 conditions for the flow: level and velocity. Your level is increasing due to the presence of the obstacle, but GroovyBC does not allow the flow to reach the boundary (see how there is no water above your given level for the cells adjacent to the inlet). Depending on what was your goal, taking the inlet far away enough from the cylinder may solve your problem, if you want to prescribe both level and velocity. If what you need to impose is only a discharge (velocity) I guess you should leave alpha1 as zeroGradient and code a BC to calculate the wet area and apply the calculated velocity to such area. In this case you most probably can reach a stable state with your current domain. Best, Pablo

the inlet velocity is set quite low while keep the water level, now the result is fine!

Btw, how to set the outlet BCs to achieve the same water level as inlet's?

best,

David
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 November 23, 2013, 13:06 #4 New Member   Baek, Dong Hae Join Date: Jan 2013 Location: Seoul Posts: 16 Rep Power: 2 hi keepfit can i ask BC of your case? U and p_rgh I am carrying out the case similar to yours

 Tags hydraulic jump, interfoam, sst k-omega

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