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Showing results 1 to 13 of 13 Search took 0.00 seconds. Search: Posts Made By: Martin Hegedus

Forum: Main CFD Forum March 19, 2012, 18:57

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus Yikes, this thread is almost a year old. I did... Yikes, this thread is almost a year old. I did quickly scan it, but can't say I remember all the details. At 70,000 I don't think a RANS model is appropriate, but it goes give you insights into...

Forum: Main CFD Forum March 15, 2011, 17:09

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus I do agree that the flow is unsteady. ... I do agree that the flow is unsteady. Unfortunately I'm running these on my laptop which doesn't have the horse power to adequately model the unsteady flow.

Forum: Main CFD Forum March 15, 2011, 16:00

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus No, I did not run laminar. The flow is sub... No, I did not run laminar. The flow is sub critical and, as can be seen from the Re 5000, a big bubble exists. If I run laminar the bubble will pop, resulting in unsteady flow. In my opinion, at...

Forum: Main CFD Forum March 14, 2011, 14:04

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus What is one looking for when choosing a good... What is one looking for when choosing a good turbulence model for low Reynolds number flow? For example, I've attached a SA (fully turbulent) run for Mach 0.10, alpha=7, and Re=5000 over a...

Forum: Main CFD Forum March 11, 2011, 18:47

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus What angles of attack did you run and did you get... What angles of attack did you run and did you get a bubble at the lower Re number?

Forum: Main CFD Forum March 9, 2011, 18:34

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus Cool. So it seems, when I look at your first... Cool. So it seems, when I look at your first paper, that our SA results are in the ball park of the experiment. Granted we don't have a bubble. Unfortunately, to even hope to get a bubble, the...

Forum: Main CFD Forum March 9, 2011, 16:33

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus Oh, just remembered, two equation turbulence... Oh, just remembered, two equation turbulence models may need less than y+=1, maybe y+=0.2. Not sure why but it has something to do with the algorithm and not physics.

Forum: Main CFD Forum March 9, 2011, 16:26

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus Ooops, looking at my low viscous CX values for Re... Ooops, looking at my low viscous CX values for Re 500,000 I realize that I used the wrong grid, i.e. the y+=1 for Re 70,000. I was also wondering why my Re 500,000 lift result was so far from 2pi. ...

Forum: Main CFD Forum March 9, 2011, 15:11

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus Oh, I forgot to mention, the eddy viscosity at... Oh, I forgot to mention, the eddy viscosity at the trailing edge for Re 500,000 is about 160 times larger than the laminar viscosity.

Forum: Main CFD Forum March 9, 2011, 15:00

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus Well, I'm glad I'm not in your shoes! 1) I'm... Well, I'm glad I'm not in your shoes! 1) I'm not sure what the story is with your (i.e. Fluent's) k-omega sst transitional turbulent viscosity. The contour plot of the overall field does not look...

Forum: Main CFD Forum March 8, 2011, 19:03

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus Sorry, Truffaldino, I think I mislead you. I... Sorry, Truffaldino, I think I mislead you. I gather you plotted eddy viscosity on the actual surface rather than in the flow field. The eddy viscosity on the surface will be very small. Instead,...

Forum: Main CFD Forum March 8, 2011, 13:30

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus I gather what you are saying is that, even for an... I gather what you are saying is that, even for an unsteady problem, your residuals have not converged enough. Since you mentioned separation bubble one of my thoughts is that your k-omega sst...

Forum: Main CFD Forum March 7, 2011, 20:17

Replies: 51 Two-equation turbulent models: low re airfoils Views: 20,831 Posted By Martin Hegedus Why do you expect your solution to converge, i.e.... Why do you expect your solution to converge, i.e. be steady? I assume that is what you mean, i.e. converge to steady state. I'm not familiar with FLUENT, but I assume you can limit the magnitude...

Showing results 1 to 13 of 13

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