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Boundary conditions outlet

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Old   November 27, 2015, 07:34
Default Boundary conditions outlet
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Sarah Leenknegt
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Dear,

I am trying to solve a simple test case (2 inlets, 2 outlets, buoyant flow, steady state, incompressible) and have problems with defining my outlets so they behave as I want.

Details
- inlet 1
velocity: fixed velocity
pressure: fixedfluxpressure
pressure_rgh: fixedfluxpressure
temperature: fixedvalue

- inlet 2
velocity: fixed velocity
pressure: fixedfluxpressure
pressure_rgh: fixedfluxpressure
temperature: fixedvalue

- outlet 1
velocity: flowrateinletvelocity (positive, patch outlet)
pressure: fixedfluxpressure
pressure_rgh: fixedfluxpressure
temperature: fixedvalue

- outlet 2
velocity: pressureInletOutletVelocity(patch outlet)
pressure: fixedfluxpressure
pressure_rgh: totalpressure
temperature: fixedvalue

The idea is that I define the total inflow through the inlets, I define the outflow via one of the outlets and the continuity results in the correct outflow via the second outlet.

However, I get too high outflow over outlet 1 and additional outflow over outlet 2. The mass balance just doesn't make sense..

What am I doing wrong?

Thank you!

Sarah
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Old   November 28, 2015, 10:34
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Joachim Herb
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Have you tried calculated for the pressure boundaries? Also for the outflow regions fixedValue for temperatures does not sound correctly. Better should be zeroGradient or inletOutlet.
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buoyancy driven flow, incomp, outlet boundary condition, pressure and velocity

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