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Old   April 4, 2005, 07:23
Default reversed flow
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hi all,

i am a novice CFD user,investigating the flow separation around an airfoil. My biggest worry now is that these error messages regarding "reversed flows on outflow" keeps popping up. This causes my iterations,Cl and Cd to "oscillate" and will never converge or flatten out.

i have tried changing my BC from outflow to pressure outlet and increasing the distance between the airfoil and the BC, but to no avail.

I have exhausted all possible means,based on my limited knowledge, to correct this problem. Anybody please advise.....i seek your wisdom.

p.s - anybody reckons that the reverse flows have anything to do with meshing,grids and the likes?
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Old   April 4, 2005, 07:24
Default Re: reversed flow
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thanks heaps in advance!
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Old   April 4, 2005, 07:53
Default Re: reversed flow
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What kind of bc are you using? pressure outlet I suppose...Try using the far-field bc. That warning will disappear! What's is your Mach no? Luca
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Old   April 4, 2005, 13:42
Default Re: reversed flow
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Do not use Outflow if you observe a reverse flow. Outflow BC fails in such a case. For aerodynamic flows, Far Field BC is the appropriate choice. Pressure Outlet happens to be a better choice over Outflow in case of reverse flow. only requirement is that you should have some meaningful estimate of downstream pressure and temeprature (if you have energy equation).

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