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ZeroGradient pressure Outlet BC prob (adjustPhi.C) |
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March 23, 2010, 06:52 |
ZeroGradient pressure Outlet BC prob (adjustPhi.C)
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#1 |
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Stylianos Kyriacou
Join Date: Mar 2010
Location: Cyprus - Athens - Austria - Zurich
Posts: 27
Rep Power: 16 |
Hello Everyone
I've been trying to set-up a Rotor-Stator case for MRFSimpleFoam (my goal is to obtain an initial solution to then use with turbDyMFoam for an unsteady calculation). I've succeeded on getting a converged solution via MRFSimpleFoam but i observed that i had a strange pressure distribution near the outlet (a pressure step exactly at the last nodes before the outlet). After some search in previous threads i found out that a good idea is to use zeroGradient (with pRefCell and pRefValue) as outlet BC. My initial BCs were: U: INLET { type flowRateInletVelocity; flowRate 0.750; value uniform (0 0 0); } OUTLET { type inletOutlet; value uniform (0 0 0); inletValue uniform (0 0 0); } P: INLET { type zeroGradient; } OUTLET { type fixedMeanValue; meanValue 0; } My modified BCs are: U: INLET { type flowRateInletVelocity; flowRate 0.750; value uniform (0 0 0); } OUTLET { type zeroGradient; } P: INLET { type zeroGradient; } OUTLET { type zeroGradient; } but with the new BC set up (and although i initialized my U field with a sensible value) i get this error: Continuity error cannot be removed by adjusting the outflow. Please check the velocity boundary conditions and/or run potentialFoam to initialise the outflow. Specified mass inflow : 0.75 Specified mass outflow : 0 Difference : 0.75 Adjustable mass outflow : 0 I've then went to adjustPhi.C to check out (maybe i was missing something) and i've seen that the part that calculates Specified mass outflow, Specified mass inflow and Adjustable mass outflow has undergone a recent bug fix (// HJ, 12/Feb/2010) and i was wondering if someone had successfully used it since then ? Thanks for your help Stylianos |
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March 23, 2010, 09:44 |
Pressure step exactly at the last nodes before the outlet
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#2 |
New Member
Stylianos Kyriacou
Join Date: Mar 2010
Location: Cyprus - Athens - Austria - Zurich
Posts: 27
Rep Power: 16 |
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March 23, 2010, 10:38 |
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#3 |
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Kevin Smith
Join Date: Mar 2009
Posts: 104
Rep Power: 17 |
Your BCs on pressure are not well defined; try using total pressure on the outlet.
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March 23, 2010, 13:28 |
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#4 |
New Member
Stylianos Kyriacou
Join Date: Mar 2010
Location: Cyprus - Athens - Austria - Zurich
Posts: 27
Rep Power: 16 |
If the outlet is part of the rotating portion of the mesh dose that create a problem for MRFSimpleFoam?
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