# Oscillatory inlet velocity profile

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 March 10, 2012, 12:58 Oscillatory inlet velocity profile #1 New Member   Join Date: Dec 2011 Posts: 3 Rep Power: 7 Dear All, I'm trying to validate openFoam to simulate oscillating flow fields. I want to simulate 2D channel flow with oscillating inlet velocity. I'm using icoFoam as solver, the velocity inlet bc that I want to imposed is of the form u(t)=a+b*sin(2pi*f*t), where a, b are constant, t is time and the f is frequency of oscillation. Moreover I've imposed 0 pressure at the outlet and no-slip condition at the wall. I'v tried to used the oscillatingFixedValue as boundary condition type for inlet velocity. The solution doesn't seem to converge. Have you got any suggestion? Has somebody used oscillatingFixedValue bc before? Is it proper to describe my inlet condition? Thanks in advance.

 March 10, 2012, 15:20 #2 Senior Member     mauricio Join Date: Jun 2011 Posts: 141 Rep Power: 10 Hi! you say your solution doesnt seem to converve... but you're doing a transient solution... you should operate with low residuals, but it won't converge to say.. e-5, e-7.... at most i guess 1e-2 maybe 1e-3, unless it's a very shy transient case.. __________________ Best Regards /calim "Elune will grant us the strength"

April 3, 2012, 00:25
#3
Member

Albert Tong
Join Date: Dec 2010
Location: Perth, WA, Australia
Posts: 76
Blog Entries: 1
Rep Power: 9
Hi Alinve,

Glad to know someone doing similar research. I am thinking the inlet boundary condition for pressure is also essential for the oscillating flow simulation. Be noted that the velocity at out BC changes with time. Can you specify those BCs that were imposed in your case?

Quote:
 Originally Posted by alinve Dear All, I'm trying to validate openFoam to simulate oscillating flow fields. I want to simulate 2D channel flow with oscillating inlet velocity. I'm using icoFoam as solver, the velocity inlet bc that I want to imposed is of the form u(t)=a+b*sin(2pi*f*t), where a, b are constant, t is time and the f is frequency of oscillation. Moreover I've imposed 0 pressure at the outlet and no-slip condition at the wall. I'v tried to used the oscillatingFixedValue as boundary condition type for inlet velocity. The solution doesn't seem to converge. Have you got any suggestion? Has somebody used oscillatingFixedValue bc before? Is it proper to describe my inlet condition? Thanks in advance.
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Kind regards,

Albert

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