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

Equation in Turbulent Intensity

Register Blogs Community New Posts Updated Threads Search

View Poll Results: What is the equation used in turbulent intensity?
The square of the standart deviation of the mean velocity divided by the mean velocity itself? 1 50.00%
Or another equation? 1 50.00%
Multiple Choice Poll. Voters: 2. You may not vote on this poll

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   July 8, 2023, 12:42
Question Equation in Turbulent Intensity
  #1
New Member
 
Guilherme Grácio
Join Date: Jul 2023
Posts: 1
Rep Power: 0
gbgracio is on a distinguished road
What is the equation used to determine the Turbulent Intensity in the fluent solution software?
gbgracio is offline   Reply With Quote

Old   July 8, 2023, 14:16
Default
  #2
Senior Member
 
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,754
Rep Power: 66
LuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura about
The square of the (temporal) standard deviation of the mean velocity is zero because it is a mean. Clearly this is not what you mean...

However, there is the caveat that you cannot get the fluctuations, which if you remember is why we have turbulence models in the first place. So, the rmse of the fluctuations is back-calculated from \sqrt{\frac{2}{3}k}

Next is the issue is which mean velocity to use. You can take either the local mean velocity or a bulk average velocity or free stream velocity. For conventional reasons, most people use one of the latter ones. So... Fluent normalizes by the reference velocity in reference values which is a user specified number and default is 1.

If you want to calculate a turbulence intensity using local mean velocity, you have to create your own field function.
LuckyTran is online now   Reply With Quote

Reply

Tags
equations, fluent, scale factor, turbulence intensity


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
Turbulent Diffusion for Temperature Equation Tobi OpenFOAM Programming & Development 6 July 8, 2019 04:28
Problem with divergence TDK FLUENT 13 December 14, 2018 07:00
How to calculate Turbulent Intensity? prem FLUENT 10 September 29, 2018 10:46
error message cuteapathy CFX 14 March 20, 2012 07:45
Turbulent intensity swe704 Main CFD Forum 0 November 13, 2009 04:42


All times are GMT -4. The time now is 07:50.