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

k-e equation in in cartesian coords

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 15, 2003, 19:46
Default k-e equation in in cartesian coords
  #1
carlslack
Guest
 
Posts: n/a
Hi,

I'm trying to expand the k-epsilon equations from cartesian tensor notation to cartesian coordinates to form a system of equations for finite element analysis.

Both the k- and e-equations contain a term with the Reynolds stresses expressed as follows:

( @Ui/@Xj + @Uj/@Xi ) ( @Ui/@Xj)

Does this represent a scalar quantity (ie the scalar product of the two tensors), or a 3x3 matrix product in 3D?

Thanks in advance, -CS
  Reply With Quote

Old   January 15, 2003, 22:45
Default Re: k-e equation in in cartesian coords
  #2
Linfeng BI
Guest
 
Posts: n/a
Any term in k and e equations is scalar because k and e themselves are scalars.
  Reply With Quote

Old   January 20, 2003, 09:45
Default Re: k-e equation in in cartesian coords
  #3
Bredberg
Guest
 
Posts: n/a
What you are looking at is part of the production term in k and eps-equation, which are - yes a scalar. However in order to compute the production term you need to cycle through i and j indices from 1 to 3, hence the expression becomes something like:

P_k=\nu_t((dU/dy+dV/dx)dU/dy+(dU/dz+dW/dx)dU/dz+....

/Jonas
  Reply With Quote

Reply

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
mass flow in is not equal to mass flow out saii CFX 12 March 19, 2018 06:21
Calculation of the Governing Equations Mihail CFX 7 September 7, 2014 07:27
Constant velocity of the material Sas CFX 15 July 13, 2010 09:56
Viscosity and the Energy Equation Rich Main CFD Forum 0 December 16, 2009 15:01
Two-Phase Buoyant Flow Issue Miguel Baritto CFX 4 August 31, 2006 13:02


All times are GMT -4. The time now is 02:20.