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Low Re Backward facing step

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Old   April 11, 2005, 10:55
Default Low Re Backward facing step
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Riaan
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Hi guys,

I am currently modelling a backwards facing step at relatively low Re (<<1e-6).

I have tried the Realizable k-e model with non-equilibrium wall functions, but I am having trouble with convergence.

My Y+ values are of the order 1, since the step region is relatively small compared to the rest of the domain, and I need sufficient nodes to capture the flow features - so if I use a y+>30, I just don't have enough nodes in the region of interest.

Anyone have suggestions? I am thinking k-w SST model, since it should have a low-Re correction - but would y+ = 1 be good for this model?

Thanks! Riaan
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Old   April 12, 2005, 02:49
Default Re: Low Re Backward facing step
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Markus
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Hi Riaan

Ever thought about a laminar flow regime at your Re ?

br, Max
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Old   April 12, 2005, 17:50
Default Re: Low Re Backward facing step
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Riaan
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I doubt the flow will be laminar in the re-attachment region, or in the circulation region aft of the step.
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Old   April 14, 2005, 03:21
Default Re: Low Re Backward facing step
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Markus
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I assume your Re of 1e-6 is based on inlet velocity and inlet cross section. I am quite sure that there is no transition to turbulent flow even in the areas you have mentioned. By the way, I think there is a FLUENT tutorial about your case, which highlights laminar and turbulent flow over a backward facing step.

Cheers
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