# specifying turbulance from laminar

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

 February 12, 2007, 06:48 specifying turbulance from laminar #1 asghari Guest   Posts: n/a Hi all; How can we distinguish between turbulance from laminar flows in CFD commercial softwares or another codes? suppose in my case ,in the biginning, my code converges,then i increase the velocity in inlet as much as fluid place in the turbulent flows,if i use no turbulance model what event is possible to happend? Thanks in advance for everybody help me.

 February 12, 2007, 09:13 Re: specifying turbulance from laminar #2 john deas Guest   Posts: n/a It might have problems to converge, or, you might have results different from the experience, because one term of the equation which is negleted in laminar flow will be completely missing. You won't be using the equations that describe your physical system.

 February 13, 2007, 09:39 Re: specifying turbulance from laminar #3 Asghari Guest   Posts: n/a Thank you, But you suppose a case where Reynolds number=500(Low Reynolds), how can i discover that it is turbulent or laminar? I usually solve it in laminar flow , whereas flow may be turbulent. Thanks in advance for any help.

 February 13, 2007, 14:08 Re: specifying turbulance from laminar #4 John Deas Guest   Posts: n/a You can make both calculation for one general case, and look at the turbulent energy for the turbulent case. Then you can extrapolate your results to similar geometries.

 February 14, 2007, 03:32 Re: specifying turbulance from laminar #5 asghari Guest   Posts: n/a Ok,but I can't still underestand how can i specify that a sample case is laminar or turbulent flow. can you present for me a detailed discussion for this object. you tell me in previous message "You can make both calculation for one general case, and look at the turbulent energy for the turbulent case" , but you did'nt indicate to turbulent criterion .For example , suppose i compute a flow using laminar model , whereas flow might be turbulent , How is this capable of distinguish

 February 14, 2007, 04:17 Re: specifying turbulance from laminar #6 john deas Guest   Posts: n/a For example, you can compare in your sample zone with obstacles and zones without obstacles. If in the obstacle zone you have significatly more turbulent energy, you can deduce that using a laminar model will cost you a lot of information in this zone. As for a quantitative criterion for this... Well I have none (I am a newly introduced to CFD )

 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 Jade M CFX 14 June 15, 2016 09:36 junbbung FLUENT 1 December 2, 2012 06:57 sachin OpenFOAM 1 February 12, 2011 10:07 kjetil OpenFOAM Running, Solving & CFD 3 July 21, 2009 09:15 MDG FLUENT 0 October 31, 2006 17:45

All times are GMT -4. The time now is 05:10.