CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

to determine Integral length scale in Fluent

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

Like Tree1Likes
  • 1 Post By CeesH

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   February 6, 2017, 02:28
Default to determine Integral length scale in Fluent
  #1
Senior Member
 
raunak jung pandey
Join Date: Jun 2016
Posts: 102
Rep Power: 10
raunakjung is on a distinguished road
Hello everyone

I am trying to calculate integral length scale in Fluent for a fluidic oscillator. My objective is to carry out LES simulation.
I am using the expression :

integral length scale l0 = k^1.5 /e where k - turbulent kinetic energy and e is eddy dissipation.
During post processing maximum and minimum values of turbulent kinetic energy and eddy dissipation rate is given. Can these values used to determine integral length scale.

If not what is the process to determine integral length scale?

Thank You

Last edited by raunakjung; February 6, 2017 at 04:43.
raunakjung is offline   Reply With Quote

Old   February 6, 2017, 03:56
Default
  #2
Senior Member
 
Cees Haringa
Join Date: May 2013
Location: Delft
Posts: 607
Rep Power: 0
CeesH is on a distinguished road
You can make a custom field fuction (under define) with the required equation. This will calculate the length scale in every grid cell. You can then plot it as a contour plot, export it, like you could do with any field. You can also define an equation in CFD post alternatively.
CeesH is offline   Reply With Quote

Old   February 6, 2017, 04:46
Default
  #3
Senior Member
 
raunak jung pandey
Join Date: Jun 2016
Posts: 102
Rep Power: 10
raunakjung is on a distinguished road
Quote:
Originally Posted by CeesH View Post
You can make a custom field fuction (under define) with the required equation. This will calculate the length scale in every grid cell. You can then plot it as a contour plot, export it, like you could do with any field. You can also define an equation in CFD post alternatively.
Thank You for your answer. I made a custom field function calculator to determine integral length scale. I have the maximum and minimum values. My goal is to carry out LES simulation. Which value should I use to determine the size of my grid for LES simulation. The maximum or minimum.

Thank YOU
raunakjung is offline   Reply With Quote

Old   February 7, 2017, 10:03
Default
  #4
Senior Member
 
Cees Haringa
Join Date: May 2013
Location: Delft
Posts: 607
Rep Power: 0
CeesH is on a distinguished road
For LES, calculate the Kolmogorov scale, and try to locally refine your mesh to approx. 5-10x the Kolmgorov scale in the bulk. The finer, the more scales you resolve of course.
Darko likes this.
CeesH is offline   Reply With Quote

Reply

Tags
eddy dissipation rate, integral length scale, turbulent kinetic energy

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Evaluation of length scale ratio for LES, DES, SAS etc. siw CFX 12 May 19, 2016 03:25
Turbulence length scale and integral length scale rizhang CFX 2 April 22, 2016 08:22
Modelled Length Scale in SAS-SST Simulation jego Main CFD Forum 0 January 16, 2016 07:45
DPM: Particle Tracking Madhukar FLUENT 1 July 24, 2007 04:51
Von Karman Integral Length Scale Txingurri Main CFD Forum 0 May 2, 2002 13:05


All times are GMT -4. The time now is 00:13.