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

Could Fluent initialize flow from time-average field data?

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

Like Tree2Likes
  • 2 Post By LuckyTran

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 25, 2016, 22:21
Default Could Fluent initialize flow from time-average field data?
  #1
New Member
 
Howard Zhang
Join Date: Oct 2014
Posts: 12
Rep Power: 11
hongfu2233 is on a distinguished road
Hi all,
Could Fluent initialize flow from time-average field data and how?
Thanks
hongfu2233 is offline   Reply With Quote

Old   February 9, 2017, 10:05
Default
  #2
New Member
 
Howard Zhang
Join Date: Oct 2014
Posts: 12
Rep Power: 11
hongfu2233 is on a distinguished road
no one help me?
hongfu2233 is offline   Reply With Quote

Old   February 10, 2017, 04:31
Default
  #3
Member
 
Join Date: Jun 2016
Posts: 66
Rep Power: 11
Zbynek is on a distinguished road
You can initialize a case with any data if you have them in an appropriate format. If you want someone to give you a more specific answer, you should mention whether you already have the time-averaged data and if yes, how you obtained them and thus in which format they are.
Zbynek is offline   Reply With Quote

Old   February 10, 2017, 05:38
Default
  #4
New Member
 
Howard Zhang
Join Date: Oct 2014
Posts: 12
Rep Power: 11
hongfu2233 is on a distinguished road
Thanks for your reply! I have gotten the time-averaged data using the utility of Fluent (Run Calculation => Data Sampling for Time Statistics). I would like to know how can I initialize flow from this time-averaged data?
hongfu2233 is offline   Reply With Quote

Old   February 10, 2017, 06:35
Default
  #5
Member
 
Join Date: Jun 2016
Posts: 66
Rep Power: 11
Zbynek is on a distinguished road
Ok, I do not have a great answer since I never did this so I will just give you ideas that just pop out in my head.

You may try to open the .dat file in a text editor and locate the time-averaged data. These use to replace the instantaneous data. If you do not have any time-averaged data in the .dat file, you should go to File->Export->Solution Data... and choose the quantities you want to export in the .dat file. Alternatively, you may get to the time-averaged data through a UDF (check Time-Sampled Data chapter) and save them in the memory. It will require some time from you to understand how the .dat file is arranged. Important - when exporting the .dat file, uncheck the Binary option so the data is written in ASCII and you are able to open and modify it in a text editor.

I know that this looks like a cumbersome solution. Maybe someone can come up with something smoother.
Zbynek is offline   Reply With Quote

Old   February 14, 2017, 21:08
Default
  #6
New Member
 
Howard Zhang
Join Date: Oct 2014
Posts: 12
Rep Power: 11
hongfu2233 is on a distinguished road
Thanks again, it sounds really tedious. I am looking for a post-processing software which can import and export Fluent data. Do you have any idea?
hongfu2233 is offline   Reply With Quote

Old   February 14, 2017, 23:09
Default
  #7
Senior Member
 
Lucky
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 5,685
Rep Power: 66
LuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura aboutLuckyTran has a spectacular aura about
Quote:
Originally Posted by hongfu2233 View Post
Thanks for your reply! I have gotten the time-averaged data using the utility of Fluent (Run Calculation => Data Sampling for Time Statistics). I would like to know how can I initialize flow from this time-averaged data?
There is a way to do it entirely within Fluent. I have written up the steps several times but I can't find the exact commands so I write just the outline. Maybe if your google skills are keen enough, you can dig up my old post.

It requires a few steps, a little tedious but not that bad. The problem is the time-averaged data are stored in new variables, whereas the raw variables are the instantaneous quantities. Unfortunately you cannot set the instantaneous quantities equal to the time-averaged ones directly and need a workaround. Fluent does not let you patch using the time-averaged fields, but it does let you patch using a custom field function.

What you need to do is define a bunch of custom field function. Make a field function for each of the time-averaged variables you need. These are just dummy functions so you can call them whatever, but define these field functions as equal the time-averaged variables that you get from your data sampling. I.e. a dummy x-velocity that will be equal to the mean x-velocity.

Now after you have done this for all the variables, you can now go the initialization pane and use the patch command. You can patch custom field functions onto the instantaneous variables. So patch (or overwrite) the x-velocity using the dummy x-velocity field.

For other software. Tecplot is great if you have access to it. But using the method I wrote above is much better because Fluent doesn't do any interpolation.
hongfu2233 and Zbynek like this.
LuckyTran is online now   Reply With Quote

Old   February 15, 2017, 04:10
Default
  #8
New Member
 
Howard Zhang
Join Date: Oct 2014
Posts: 12
Rep Power: 11
hongfu2233 is on a distinguished road
It works! Thank you, LuckyTran!
hongfu2233 is offline   Reply With Quote

Reply

Tags
initialize flow, time-average field dat

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
CFD by anderson, chp 10.... supersonic flow over flat plate varunjain89 Main CFD Forum 18 May 11, 2018 07:31
[Other] dynamicTopoFVMesh and pointDisplacement RandomUser OpenFOAM Meshing & Mesh Conversion 6 April 26, 2018 07:30
Time Averaged Data (for flow field) TECPLOT biancab Tecplot 6 November 30, 2016 12:01
Sudden jump in Courant number NJG OpenFOAM Running, Solving & CFD 7 May 15, 2014 13:52
plot over time fferroni OpenFOAM Post-Processing 7 June 8, 2012 07:56


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