November 24, 2009, 19:44
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Major differences between Comsol and OpenFOAM, steady state diffuser singlephase flow
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#1
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Senior Member
Join Date: Mar 2009
Location: Norway
Posts: 137
Rep Power: 17
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Dear OpenFOAM community,
I just finished a simulation case in Comsol to verify the separation limits for diffusers. As a reference I used the characteristics in White's Fluid Dynamics.
Comsol returned pretty plausible results, having backflow at the outlet when the diffuser angle was set too large. On the other hand, creating a similar case in OpenFOAM using simpleFoam, still using water and 4m/s as inlet condition, the solution turns out very different; separation occurs almost immediately after diffuser inlet - at this angle (7 deg half angle) the flow "should" be uniform. What may be wrong? Wall functions are enabled for k and epsilon ...
Illustrations attached.
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Linear Mode
