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February 9, 2021, 06:33 |
Fluctuations due to buoyancy in Freejet
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New Member
Marcel
Join Date: Dec 2020
Location: Germany
Posts: 17
Rep Power: 5 |
Dear CFD Users,
i am working on a freejet simulation with StarCCM+. Because the freejet consists of hydrogen and the ambient gas is air, the jet will be especially further downstream buoyancy dominated. I think this buoyancy makes some problems in this case, because with gravitation deactivated (and therefore no buoyancy) the fluctuations do not appear. Simulation Details: - steady - multicomponent Gas (H2 and Air) - non reacting BC: Inlet (bottom of the picture, the beginning of the tube): Velocity Inlet with species condition 100% Hydrogen Walls (left and right side in the picture): Wall with species condition: 100% Air Outlet (Top of the picture): Pressure Outlet with ambient pressure and species condition 100% air Problem: At some area the jet has heavy fluctuations, i attatch a picture of the Mole Fraction of H2 after 1000 iterations I attach a picture of the residuals plot as well. Someone any idea how to solve this Problem? I want to validate my CFD result later with experimental data, so it would be perfect to get a smooth, steady result to do that. Thanks for your help! |
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