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April 15, 2016, 08:45 |
Timescale convergence?!
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#1 |
New Member
Tim
Join Date: May 2014
Posts: 8
Rep Power: 12 |
Hi guys,
I'm running a NACA0015 profile at low reynolds numbers (10000-1000000) with steady sst including gamma-theta transition model. I varied my timescale to become a converged (steady state) solution. But I found out, that in some cases both decreasing and increasing the timescale from my converged timestep gives me an oscillating (transient) result. My question is, does the "good" timescale maybe damp transient effects so the solution can convergate? Cheers |
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April 15, 2016, 14:57 |
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#2 |
Senior Member
Join Date: Jun 2009
Posts: 174
Rep Power: 17 |
at what AOA?
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April 16, 2016, 05:44 |
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#3 |
New Member
Tim
Join Date: May 2014
Posts: 8
Rep Power: 12 |
AoA=0, critical Re from 10000 til 100000. above 100000 it's ok.
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April 16, 2016, 07:42 |
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#4 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,854
Rep Power: 144 |
If the flow is not in the gross separated flow regime (which I suppose it is not at AOA=0), then this is probably a laminar separation bubble. They tend to be unstable and jiggle about quite a bit. If the bubble is small it probably does not affect things much but at low-moderate Re (50k-200k for many airfoils) the separation bubble can be large. It might be important in this Re range.
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Tags |
steady, timescale, transient |
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