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April 15, 2016, 05:26 |
monitoring Velocity fluctuation
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#1 |
New Member
Nazanin Ansari
Join Date: Sep 2013
Posts: 12
Rep Power: 13 |
Hi everyone, i am simulating a delta wing to validate some results for literature.
I have some questions about it. -For validating turbulence intensity distributions, Urms, Vrms and Wrms is it ok to draw the Reynolds stresses in CFD-Post? Are they the same?(Using Reynolds stresses methods). If yes, why are my results quite different from the literature?Is there any explanation for it? -How can i calculate and draw the amplitude spectra of fluctuating pressure coefficient in ANSYS CFX?(The photos from the literature and some values validation are to be seen in attached photos) 1.jpg 2.jpg ^3.png 4.jpg 5.jpg |
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April 15, 2016, 07:59 |
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#2 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,854
Rep Power: 144 |
Is your first question:
Can I compare Reynolds stresses to RMS fluctuations? No, but they are related. Look at any turbulence modellign textbook for details. OR What is my simulation inaccurate? FAQ: http://www.cfd-online.com/Wiki/Ansys..._inaccurate.3F Second Question: Define a monitor point recording pressure at the location you wish to measure and do a transient simulation. This will give you the pressure versus time history. Then process the pressure history using whatever filtering approach you like to separate the mean from fluctuating components. |
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April 15, 2016, 08:13 |
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#3 |
New Member
Nazanin Ansari
Join Date: Sep 2013
Posts: 12
Rep Power: 13 |
Dear Glenn,
thank you very much for your answer, i have checked it in the turbulent book by Pope, but does'nt seem to find it. Could you please tell me how these two are related? |
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April 15, 2016, 08:15 |
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#4 |
New Member
Nazanin Ansari
Join Date: Sep 2013
Posts: 12
Rep Power: 13 |
i just know that the Reynolds stresses are the covariance of velocity fluctuations. Is that correct?
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April 16, 2016, 07:47 |
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#5 |
Super Moderator
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,854
Rep Power: 144 |
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