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October 29, 2018, 11:08 |
Estimating Kolmogorov scale in LES
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#1 |
New Member
Brian
Join Date: Mar 2009
Posts: 17
Rep Power: 17 |
Dear all,
I was hoping someone might be able to advise me on how best to estimate the Kolmogorov (length) scale in practical terms in CFX. I am running LES simulations using the WALE SGS, and am pretty new to running LES simulations at all. So far, my best idea has been to follow the treatment from Pope's Turbulent Flows (section 13.3.3) which has: where: allowing to be calculated directly from the velocity/strain tensors (averaged appropriately and saved out as transient statistics), and then use to estimate the Kolmogorov length scale. This doesn't seem like a particularly direct method to me though; is there a better/faster way of doing it? Thanks in advance! |
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October 29, 2018, 18:37 |
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#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,864
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There are a whole bunch of ways to estimate epsilon, the Fluent manual lists a lot of them (http://jullio.pe.kr/fluent6.1/help/html/ug/node178.htm)
But note these estimates rely on knowledge of things like length scales, turbulent viscosity ratioes and so on, and these parameters can be difficult to determine as well. You will have to determine whether any of these approaches are going to work better than the direct (and more formally correct) method you describe.
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November 1, 2018, 07:44 |
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#3 |
New Member
Brian
Join Date: Mar 2009
Posts: 17
Rep Power: 17 |
Brilliant - thanks! I'll have a look and see if any of those methods seem reasonable.
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Tags |
kolmogorov, les, scales, turbulence |
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