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

Turbulence intensity missing!!

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

Reply
 
LinkBack Thread Tools Display Modes
Old   June 11, 2015, 09:49
Exclamation Turbulence intensity missing!!
  #1
Member
 
Martin
Join Date: May 2015
Posts: 30
Rep Power: 4
Martin1 is on a distinguished road
Dear Friends,

I am using a Smagorinsky LES model in my simulations but I can't make a contour plot of the turbulence intensity since that option does not exist in the contours list. I have to make a user defined function but don't know how the turbulent intensity is defined in fluent for this turbulent model.

I have used the equation TI = u'/u

where u'=( 1/3 * (uv'^2 + uw'^2 +vx'^2) )

where the terms uv', uw' etc are the resolved reynolds stress components obtained under unsteady statistics. But this does not give reasonable contour plots.

Can anyone please help me to define the turbulent intensity.
Martin1 is offline   Reply With Quote

Old   June 11, 2015, 14:25
Default
  #2
Member
 
Martin
Join Date: May 2015
Posts: 30
Rep Power: 4
Martin1 is on a distinguished road
No one can help?
Martin1 is offline   Reply With Quote

Old   May 5, 2017, 21:34
Default
  #3
New Member
 
West Bengal
Join Date: Jan 2016
Posts: 3
Rep Power: 3
susovanpal is on a distinguished road
Hello martin1. I am also having the same problem. Have you got any solution for this?
susovanpal is offline   Reply With Quote

Old   May 6, 2017, 00:32
Default
  #4
New Member
 
Swapnil Chavanda
Join Date: Jan 2017
Posts: 19
Rep Power: 2
swpnl9282@gmail.com is on a distinguished road
Hello all,
I'm doing simulation of heat exchanger.
Shell side fluid is water and tube side fluid is hot gas.
So how to capture the properties of gad only in UDF.
If anyone had idea about it, please let me know as early as possible

Sent from my Moto G (4) using CFD Online Forum mobile app
swpnl9282@gmail.com is offline   Reply With Quote

Old   May 6, 2017, 17:26
Default
  #5
Senior Member
 
Lucky Tran
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 1,886
Rep Power: 26
LuckyTran will become famous soon enoughLuckyTran will become famous soon enough
Quote:
Originally Posted by susovanpal View Post
Hello martin1. I am also having the same problem. Have you got any solution for this?
There is a resolved part of the TKE based on the fluctuation of the resolved part (the filtered) velocities. The resolved part of k, say k_resolved = 0.5(u'^2+v'^2+w'^2).

Now you need to get the turbulent kinetic energy of the subgrid scale. This is the tricky part. I forget the formula, it's hiding somewhere in the Fluent manual and Pope's book, but it involves the subgrid scale filter length, and subgridscale viscosity. I could dig it up out of my code later.

However, to get the average subgrid scale kinetic energy you still need to average it. Which means you need to create a custom field function or UDF. Custom field functions don't run in parallel pre-v18, so if you're using anything before v18 it needs a UDF.
LuckyTran is offline   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
Turbulence Intensity at inlet boudary egge24 FLUENT 1 October 10, 2015 15:56
Turbulence intensity - cross wind on a body Fabio88 Main CFD Forum 0 May 4, 2015 03:44
How to define the turbulence intensity and mixing length at an outlet (for k-eps)? david39 OpenFOAM Running, Solving & CFD 6 February 2, 2011 04:01
High turbulence intensity wenfengxie FLUENT 1 April 16, 2010 12:00
High Turbulence Intensity Problem bwg FLUENT 1 January 13, 2010 14:09


All times are GMT -4. The time now is 04:20.