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April 11, 2012, 00:56 |
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#21 | |
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Pranav
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Quote:
I'm using fluent 12.1, laminar model, AOA 0, velocity 25ms^-1, velocity inlet and pressure outlet. I got your reference values. While I used another mesh with aspect ration within 20 I had the same flow reversal problem. I used the youtube tutorials widely suggested at various posts here to mesh the 2D airfoil in ICEM CFD. Do u think this mesh will work fine https://courses.cit.cornell.edu/flue...il/02face3.htm Its from cornell university tutorial. I tried a similar density mesh and still got the flow reversal, may be I'm setting the problem wrong in fluent. Its a 10" chord length NACA 4412 that i'm trying to do simulation for. |
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April 11, 2012, 04:30 |
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#22 |
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The mesh from cornell university is certainly better than yours. Most likely is a problem of boundary conditions. What values do you use for your boundary conditions?
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April 12, 2012, 00:24 |
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#23 |
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Pranav
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I use a 20ms^-1 velocity inlet as told earlier, and then use a pressure outlet with a 0 Pa guage pressure. At the ICEM CFD, I set the solver as fluent v6 and in the BC set the FFINLET and FFOUTLET (see the geometry file) and set them as pressure farfield. Then at the fluent used the Boundary conditions to set them to velocity inlet and pressure outlet.
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April 12, 2012, 03:40 |
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#24 |
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Just to know, how are your residuals going? What solver are you using? Pressure based or density based? On how many cells do you have reverse flow?
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April 12, 2012, 09:44 |
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#25 |
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Pranav
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Pressure based, and before that, when I imported the cornell university mesh it showed default fluid and when I imported mine it showed int-fluid. Is there a problem?
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April 12, 2012, 09:59 |
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#26 |
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But from the residuals you don't have reversed flow anymore! it only happens at the beginning, and this is not a problem at all. Let the simulation run and see if it converges
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April 12, 2012, 13:09 |
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#27 |
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Pranav
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That part of snapshot was at a point of time, couldn't take for each and every line. I actually stopped the solver and took the snapshot
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April 12, 2012, 13:17 |
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#28 |
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Does this mean that the reverse flow disappears and then appears again as iterations proceed? How many iterations do you normally do? What are the levels of the residuals? Are the lift and drag stable?
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