CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > Phoenics

Time Dependent property

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

LinkBack Thread Tools Search this Thread Display Modes
Old   August 21, 2001, 17:39
Default Time Dependent property
S Rhie
Posts: n/a
I am trying to solve the problem with various air properties(desity, diffusion coeff.) according to the time variation. Can someone please help me how to do? Thanks


ps: I have phoenics 2.2

  Reply With Quote

Old   August 28, 2001, 05:43
Default Re: Time Dependent property
Posts: n/a
Dear SC Rhie

PHOENICS have implemented several models to handle fluid properties. If you are completlely sure your desired model is not included then continue to read this, otherwise stop and read POLIS entry for Fluid Properties.

It is simple but difficult to explain without to know how familiar you are with GROUND programming. Nevetheless we will try. OK?

I will assume you have a recomplilable PHOENICS version and you have designed your Q1 to solve a time dependent problem.

If you want to include a model for density (for example) insert this line into Q1 file


Now you will have to assign your time dependency into GROUND. You will need the index ISTEP for the time step and the value of DT for time step size. You should add the proper code lines for store the total physical (or dimensionless) time. Moves into the Group 9 in GROUND (Section GRND, not GRND1, nor any GRND#) and insert the desired model. You will also need the index DEN1 for density.

Suppose I have a 2D problem with a cartesian grid and I want to increase the density every time step multiplying its value by a function "GFUNCT" of the elapsed time. I have the physical (total) time stored into TOTIME. Every time step I will update TOTIME and the value of function "GFUNCT"


Then into the Group 9 (GRND density section) I will insert the following lines






Depending on how you have compiled your sources (I mean copiler options for variables) or how you declare the integer variable L0DEN1 you can move the line


to Group 1 to save some time. If your problem is 3D the procedure is a little more complex but it is still easy to implement.

I hope this helps you. Regards

  Reply With Quote

Old   August 28, 2001, 12:12
Default Re: Time Dependent property
David Glynn
Posts: n/a
Is the density really changing in time alone, and not in response to other changes in the flow? Maybe so, but this strikes me as unusual. If this really is true, you need to do it in Ground, as Kike suggests.
  Reply With Quote


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
Time Dependent Temperature Dependent BC Analysis RP Main CFD Forum 1 March 28, 2008 01:22
Temperature dependent property kdarc OpenFOAM Running, Solving & CFD 3 March 27, 2007 16:21
Geometrical dependent physical property Jiri Novak FLUENT 4 October 24, 2005 12:08
time dependent MRF ? olivier Main CFD Forum 1 April 1, 2005 10:28
time dependent mrf ? olivier FLUENT 0 April 1, 2005 07:46

All times are GMT -4. The time now is 15:01.