CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Main CFD Forum

Why to use Turbulence Model

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

Reply
 
LinkBack Thread Tools Display Modes
Old   December 29, 2006, 14:16
Default Why to use Turbulence Model
  #1
Valdemir G. Ferreira
Guest
 
Posts: n/a
Hi Dear Friends,

The question is this one:

Why one needs to use turbulence modelling?

Best Regards

VG Ferreira
  Reply With Quote

Old   December 29, 2006, 14:42
Default Re: Why to use Turbulence Model
  #2
pc
Guest
 
Posts: n/a
Practicality.

Try doing DNS for high Reynolds number flow over a complete aircraft.

  Reply With Quote

Old   December 29, 2006, 14:59
Default Re: Why to use Turbulence Model
  #3
Valdemir G. Ferreira
Guest
 
Posts: n/a
Dear PC,

I am in the same positon

Ferreira
  Reply With Quote

Old   December 29, 2006, 15:48
Default Re: Why to use Turbulence Model
  #4
pc
Guest
 
Posts: n/a
My response was somewhat tongue-in-cheek.

Seriously, though: these models are used to represent the effects of what we cannot resolve. You introduce terms for the creation/destruction/transport of turbulent kinetic energy, rather than compute the fluctuations at all scales directly and pull out the statistics from a long, expensive transient run. Modeling is currently the only practical option for most real problems and geometries of interest.

Many of these models do rather well for various problem classes, but of course they're not the whole solution. Many a degree has been awarded to people exploring turbulence modeling...

  Reply With Quote

Old   December 29, 2006, 16:48
Default Re: Why to use Turbulence Model
  #5
Valdemir G. Ferreira
Guest
 
Posts: n/a
Dear PC,

I am simulating a 3D problem using my code, and it is given segmentation fault. Is it possible to avoid this interruption by implementing the K and Epsilon equations?

Ferreira
  Reply With Quote

Old   December 29, 2006, 22:40
Default Re: Why to use Turbulence Model
  #6
TG
Guest
 
Posts: n/a
A segmentation fault is caused by an error in programming - a divide by 0 or going beyond memory limits. It has nothing whatsoever to do with implementing a turbulence model. You have a programming error - not a physics error.
  Reply With Quote

Old   December 31, 2006, 01:18
Default Re: Why to use Turbulence Model
  #7
Venkatesh V
Guest
 
Posts: n/a
Hi, If you are getting segmentation fault, I would suggest you to check the code throughly and try handle all the exceptions with proper error message so that each time you can know where your code is blowing.

Some times wrong physics my spoil the quality of solution matrix which may cause segmentation fault. Modeling turbulence would enhance the dissipation in your code, this will try to smoothout some sharp gradient which can give stability to your solver.

  Reply With Quote

Reply

Thread Tools
Display Modes

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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Wrong calculation of nut in the kOmegaSST turbulence model FelixL OpenFOAM Bugs 27 March 27, 2012 09:02
Low Reynolds k-epsilon model YJZ ANSYS 1 August 20, 2010 13:57
KOmega Turbulence model from wwwopenFOAMWikinet philippose OpenFOAM Running, Solving & CFD 30 August 4, 2010 10:26
Fan heater model: what turbulence source to use? andy20 CFX 7 March 3, 2008 17:42
SSG Reynolds Turbulence Model Georges CFX 1 February 28, 2007 17:15


All times are GMT -4. The time now is 09:10.