# TKE budget equation in LES

 Register Blogs Members List Search Today's Posts Mark Forums Read

 March 12, 2014, 00:58 TKE budget equation in LES #1 New Member   SSSSS Join Date: Jun 2011 Posts: 17 Rep Power: 8 Hi, I am calculating TKE budget equation by using solutions from LES simulation. From filtered momentum equation of incompressible flow,(Please note than variables are filtered/resolved value and filter symbol is omitted) By using linear eddy-viscosity model, , the above equation reduces to I could get tke budget equation using the above equation with time averaging like RANS where bar means time mean and tke and resolved fluctuation this equation is basically identical to the counterpart from RANS except for instead of When I applied this equation to the results of flow around a circular cylinder, I found there is imbalance around shear layer otherwise balance is made. I have checked my discretizing each term and it looks good. When I compared resolved turbulent stress (u'v', u'w' and v'w') to subgrid stress (), resolved stress is more than 99%, that means I have resolved most of turbulent field. How can I explain this imbalance around shear layer? Thanks in advance. Last edited by doctorWho; March 12, 2014 at 11:04.

 March 12, 2014, 04:49 #2 Senior Member   Filippo Maria Denaro Join Date: Jul 2010 Posts: 3,419 Rep Power: 39 According to the book of Sagaut, the equations 3.30 to 3.33 are in the form you should use. Now, is your solution statistically steady? What about production and dissipation budget?

 March 12, 2014, 11:02 #3 New Member   SSSSS Join Date: Jun 2011 Posts: 17 Rep Power: 8 FMDenaro Yes, the solution is statistically steady. As I understand, equation 3.30 of Sagaut is equation for instantaneous resolved kinetic energy not resolved turbulent kinetic energy. Also equation 3.33 is equation for unresolved kinetic energy but mine is equation for resolved turbulent kinetic energy which is following the time averaging of RANS. Do you mean that I cannot use tke equation in LES? As I check production and dissipation around shear layer, production is about 10 times larger than dissipation.

 March 12, 2014, 12:27 #4 Senior Member   Filippo Maria Denaro Join Date: Jul 2010 Posts: 3,419 Rep Power: 39 To be more clear, when you compute a LES solution your velocity field is ULES = G*u = u -u'LES then you can compute the satistical average = - Therefore, being = URANS = u -u'RANS = URANS - You can see the difference ...

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post yuyuxuan Tecplot 9 February 12, 2016 04:27 shahzeb irfan FLUENT 0 August 10, 2011 00:00 shahzeb irfan Main CFD Forum 0 August 7, 2011 23:57 Demonwolf Main CFD Forum 2 October 29, 2009 20:53 izardy amiruddin Main CFD Forum 2 July 4, 2002 08:14

All times are GMT -4. The time now is 02:22.