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January 14, 2014, 19:09 |
Want to implement a turbuence model! How?
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#1 |
Member
David
Join Date: Feb 2013
Posts: 38
Rep Power: 13 |
My advisor want me to implement a 2-equation turbulence model, like K-W or K-E, I am wondering those two equations, should I simultaneously solve them together with N-S equations?
Or, can I solve N-S equation firstly, and then treat the flow field as stable field, and then only calculate k-E equations for the fluctuating variables. Normally, how do you guys do it? Thanks. |
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January 15, 2014, 16:25 |
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#2 |
Member
Join Date: Jun 2011
Posts: 51
Rep Power: 14 |
Hi David,
I would be curious to know how you will handle the clousure problem. AFAIK u need to related the unkonw Reynolds stresses to the known mean flow variabes through the turbulent transport equations. The latest can be 1eq. models, 2eq. model or second clousures. U must end up with: Full NS eq. - Averaged NS eq. = eq. for fluctuations. Regards, |
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January 16, 2014, 11:46 |
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#3 |
Senior Member
Martin Hegedus
Join Date: Feb 2011
Posts: 500
Rep Power: 19 |
In general, the turbulence model is decoupled from the N.S. equations during the solution process.
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January 16, 2014, 23:51 |
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#4 |
Member
Join Date: Oct 2012
Posts: 46
Rep Power: 13 |
Hi!!
This is how I had implemented k-e model 1. Initialize some velocity field. 2. Calculate k. 3. Calculate epsilon 4. Calculate turb viscosity. 5. solve NS to get new velocity field. 6. if velocity < stopping criteria, goto 2, else stop. If you have any doubts, please reply back!! |
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January 17, 2014, 00:38 |
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#5 |
Senior Member
Martin Hegedus
Join Date: Feb 2011
Posts: 500
Rep Power: 19 |
A note, from what I understand, the two equation models are finicky about how the convection terms are discritized. The SA model is forgiving, so first order upwind is OK. Also, the two equation implicit methods are a little more tricky, assuming of course that an implicit method is used.
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January 17, 2014, 11:45 |
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#6 | |
Member
David
Join Date: Feb 2013
Posts: 38
Rep Power: 13 |
Quote:
THanks for all. When calculating k and epsilon, what algorithm can I use? for example, if I used SIMPLE for velocity field, do I need do any special treatment for the K and E equations? Thanks. |
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January 19, 2014, 00:03 |
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#7 |
Senior Member
TWB
Join Date: Mar 2009
Posts: 400
Rep Power: 19 |
Hi, I'm also trying to update my laminar code to turbulent. I'm reading Wilcox's turbulence modeling for CFD. Is there any books or online material which details the steps for a novice to follow?
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January 19, 2014, 01:20 |
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#8 | ||
Member
Join Date: Oct 2012
Posts: 46
Rep Power: 13 |
Quote:
Give me some time, and i'll upload a document regarding the same, just remind me once after wednesday Quote:
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January 19, 2014, 12:40 |
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#9 | |
Member
David
Join Date: Feb 2013
Posts: 38
Rep Power: 13 |
Quote:
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