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syavash March 3, 2012 18:53

Internal Flow BC: Increasing Inlet mach No.
Dear friends,

I am dealing with the internal flow problem in Fluent. I have set the pressure Inlet BC so that the inlet mach be equal to 0.77. unfortunately in the very initial iterations the inlet mach No. begins to increase until it reaches to 1.2. I have tried Far-field BC for Inlet Condition but the the result is still the same.
How can I stop increasing Mach No.?

Far March 4, 2012 02:49

What is boundary condition at outlet and its non dimensional distance in terms of characteristic length from region of influence? Can you post pic of domain, mentioning the in and out? Rule of thump: lower the outlet pressure, higher the velocity at inlet

syavash March 4, 2012 17:25

Dear Far,
The geometry belongs into a Transonic Intake and I cant show the case due to job restrictions. The outlet BC is p-outlet and total length is about 3 meters, the major problem is that I have shock formation at the inlet throat and can't make it clear whether it is because of geometry or not. Principally the geometry should act as a diffuser (because that's an Intake!!) so we shouldn't get any shocks and this is somehow troubling. I have a validation case using NASA S-Duct at Mach 0.74. Anythings seems to be right but about the intake I'm not sure.
tnx for ur consideration

Far March 4, 2012 22:17

increase the back pressure

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