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

Strange averaging in directMappedFixedValue BC

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 24, 2010, 09:28
Default Strange averaging in directMappedFixedValue BC
  #1
Member
 
Tobias Holzinger
Join Date: Mar 2009
Location: Munich, Germany
Posts: 46
Rep Power: 17
woody is on a distinguished road
Dear All,

while trying to derive my own BC from the direct mapped BC, i was wondering why there are two different averaging possibilities:

Code:
   if (setAverage_)
    {
        Type averagePsi =
            gSum(this->patch().magSf()*newValues)
           /gSum(this->patch().magSf());

        if (mag(averagePsi)/mag(average_) > 0.5)
        {
            newValues *= mag(average_)/mag(averagePsi);
        }
        else
        {
            newValues += (average_ - averagePsi);
        }
    }
Any Idea about the streching if the average differs to much?


Have FUN!
woody is offline   Reply With Quote

Old   September 7, 2012, 06:10
Default
  #2
Senior Member
 
Florian Krause
Join Date: Mar 2009
Location: Munich
Posts: 103
Rep Power: 17
florian_krause is on a distinguished road
Quote:
Originally Posted by woody View Post
Dear All,

while trying to derive my own BC from the direct mapped BC, i was wondering why there are two different averaging possibilities:

Code:
   if (setAverage_)
    {
        Type averagePsi =
            gSum(this->patch().magSf()*newValues)
           /gSum(this->patch().magSf());

        if (mag(averagePsi)/mag(average_) > 0.5)
        {
            newValues *= mag(average_)/mag(averagePsi);
        }
        else
        {
            newValues += (average_ - averagePsi);
        }
    }
Any Idea about the streching if the average differs to much?


Have FUN!
Hi guys,
I am successfully using the mapped BC for LES of turbulent flow through a 90deg bend, with the mapping region located in an (extended) straight inlet section. I switched on averaging of velocity to obtain my desired bulk velocity.

While running the simulation, I assumed that OF always computes the new velocities according to the above else statement, using the difference between the desired average and the current velocities. Then I checked the corresponding code and I'm also a bit confused by the same the if statement, specifically by the condition and the first correction method.

Any ideas?

Thanks,
Florian

Last edited by florian_krause; September 7, 2012 at 06:29.
florian_krause is offline   Reply With Quote

Reply

Tags
averaging, boundary conditions, directmappedfixedvalue


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
different between the various averaging huwei CFX 3 February 22, 2015 14:09
Strange Flamelet Generation Problem tar FLUENT 11 March 22, 2014 11:52
When to use mass flow averaging cspectre CFX 2 December 6, 2009 06:30
Averaging LES iko FLUENT 3 July 3, 2008 06:55
Reynolds averaging and k-epsilon Jaap Hoffmann Main CFD Forum 1 August 4, 2003 05:57


All times are GMT -4. The time now is 09:34.