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Boundary condition-oscillating flow

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Hi every one,
I have an oscillating flow(w.r.t time) inlet velocity profile( in the form of a Finite Fourier series expression) to be supplied as an unsteady inlet velocity boundary condition to a simple straight cylindrical duct. Note that the inlet velocity profile includes negative flow as well,that is the flow REVERSES periodically.

My requirement is that the pressure profile at the exit of the duct should evolve as a function of time as the solver solves the problem. So I cannot specify a pressure value or cannot impose any constraint on the exit pressure.So I don't know what boundary condition I need to specify at the exit of the duct in this case.

Can I get some help in this regard.Thanks in advance,

SM Ananth

2 Replies Last Post 21 mars 2011, 06:13 UTC−4
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 1 decade ago 19 mars 2011, 14:03 UTC−4
Hi

I'm not a CFD expert, but as I have understood the inflow/outflow conditions do not restrict the direction of the flow, its rather a naming convention. So why not try some of the other outflow conditions, there is not only the restricted pressure one ;) And take the time to read through the doc and the help files a couple of times

--
Good luck
Ivar
Hi I'm not a CFD expert, but as I have understood the inflow/outflow conditions do not restrict the direction of the flow, its rather a naming convention. So why not try some of the other outflow conditions, there is not only the restricted pressure one ;) And take the time to read through the doc and the help files a couple of times -- Good luck Ivar

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Posted: 1 decade ago 21 mars 2011, 06:13 UTC−4
Hello sir,

Thanks...

SM Ananth
Hello sir, Thanks... SM Ananth

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