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

USER DEFINED SCALARS

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 30, 2003, 14:35
Default USER DEFINED SCALARS
  #1
yann
Guest
 
Posts: n/a
hi,

i would want to know how to defined user scalar for which transport equation may be solved or not, by the way of pil command.

for instance if i want to define the mach number as u/sqrt(gamma*r*T) , so i dont want to define a transport equation for it, how can i define that user scalar as a function of solved and existing flow variables...

thanks

in addition i saw in some Q1 that there exist some variable that phoenics recognize such as MACH PTOT (total pressure) but i cannnot find any list of such variables in POLIS or whatever... where can i find the complete list??
  Reply With Quote

Old   July 31, 2003, 01:48
Default Re: USER DEFINED SCALARS
  #2
Rami
Guest
 
Posts: n/a
yann,

If you wish to add a transport equation for an additional variable, say var1, you should add the pill command solve(var1). You should then add BC and IC for this variable, and also define its diffusion coefficients by PRNDTL(var1)=... and PRT(var1)=... (the latter applies only for turbulent flow). You may also need to define relaxation for this variable. If only the standard transient, convection, diffusion and source available in PHOENICS are needed - then that's it. On the other hand, if you wish to have a non-standard term, e.g., a source term that depends on other variables, you should add some coding in ground either directly or by the newer methods (PLANT and INFORM).

For variables not having a conservation equation associated with, but that are rather derived from the other variables (such as the Mach number in your example), you should use store(var2) for a variable named var2.

More details may be found in POLIS (e.g., SOLVE and STORE).

I cannot help further in regards to the MACH and PTOT you mentioned. Hopefully CHAM will enlighten us in this respect.

Rami
  Reply With Quote

Old   July 31, 2003, 10:31
Default thanks but...
  #3
yann
Guest
 
Posts: n/a
thanks for your tips... but if i define a non-solved variable with STORE(var2) and i want this variable to be var2 = 0.5*U1 **2

where can i define var2 as this function, in Q1 or in ground?? thanks regards
  Reply With Quote

Old   July 31, 2003, 22:34
Default Re: thanks but...
  #4
xqy
Guest
 
Posts: n/a
in plant, you can handle it very easyly
  Reply With Quote

Old   February 7, 2004, 08:52
Default Re: thanks but...
  #5
STK
Guest
 
Posts: n/a
I HAVE THE SAME PROBLEM HOW I CAN DEFINE A VARIABLE VAR1=0.5*U1**2 AND IN PRINT-OUT TAKING THE RESULTS AS THE ABOVE FUNCTION OF THE U1 (CONVERGENCED- LAST SWEEP) 1.IF YOU KNOW A SIMPLE CODE IN GROUND AND THE CORRESPONDING COMMANDS IN Q1

2. IN PLANT MENU

THANKS IN ADVANCE
  Reply With Quote

Old   November 13, 2013, 14:23
Default transient user defined variable
  #6
Member
 
niru
Join Date: Apr 2012
Posts: 48
Rep Power: 4
Niru is on a distinguished road
I am facing a similar problem
I have variable which need not be solved for transport equations.
Var 1=areAve(liquid)@wall*Time step Size is my variable.
This is a transient simulation where areaAve changes with respect to time.
I want the values for var 1 at different times.
How to do define this variable in CFX Pre.
Niru is offline   Reply With Quote

Old   November 14, 2013, 08:46
Default
  #7
Member
 
Roman Gobitz-Pfeifer
Join Date: Dec 2009
Location: Stuttgart
Posts: 69
Rep Power: 6
Wikie is on a distinguished road
Hi Nuri,

you should place your question in the CFX forum instead of the Phoenics forum. You might have a better change to get a sufficient answer there.

cheers
wikie
Wikie is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
User defined scalars!! Mischelle FLUENT 3 July 4, 2013 10:04
user defined scalars shankar FLUENT 0 May 7, 2005 06:55
user defined scalars ramesh FLUENT 1 June 11, 2004 17:25
USER-DEFINED ARRAYS-SCALARS STK Phoenics 0 February 7, 2004 08:56
Multiple user defined scalars Hassid Samuel FLUENT 3 March 27, 2001 02:12


All times are GMT -4. The time now is 11:52.