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

difference active/passive scalar

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 21, 2005, 07:41
Default difference active/passive scalar
  #1
Torsten
Guest
 
Posts: n/a
i have an other question too. can anybody explain to me, what is the difference between active and passive scalar. yes, i have read the help-files, but i am able to make nothing of it. thank you.
  Reply With Quote

Old   April 21, 2005, 09:09
Default Re: difference active/passive scalar
  #2
4xF
Guest
 
Posts: n/a
Simple: an active scalar modifies the physical properties like density and viscosity according to the local concentration of the scalar. That means that if you have 100% of an active scalar, density and viscosity will be the same as the ones of the active scalar. Whereas for 0%, density & viscosity will be the ones of the background fluid. The passive scalar on the other hand do not influence the fluid properties, but there is still a transport equation solved for it. You can consider it as a tracer.
  Reply With Quote

Old   April 22, 2005, 03:50
Default Re: difference active/passive scalar
  #3
xhliu1
Guest
 
Posts: n/a
Hello,

Torsten, Here I have a question to ask for help: When add source to the continuity equation using my subroutine,what should I express the term of div(p) as?

Good Lucky! Thanks!
  Reply With Quote

Old   April 22, 2005, 06:06
Default Re: difference active/passive scalar
  #4
Torsten
Guest
 
Posts: n/a
Hello 4xF,

if i have an active scalar, in a cell will solved a mixing value for density, viscosity and temperature in accordance of the concentration of the scalar. what happens for a passive scalar? in the same cell i get only the density and so on of the background fluid. what does the temperatur? if the scalar has 500 K an the background fluid 300 K. i think i get a mixing temperature. is that right, that this temperature affects e.g. the density of the background fluid?

thank you!

  Reply With Quote

Old   April 22, 2005, 10:52
Default Re: difference active/passive scalar
  #5
4xF
Guest
 
Posts: n/a
If you are just interested into the variations of density with temperature during a mixing process, why don't you use the temperature (which is a transported scalar) and use a 'cold' and 'hot' source?
  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
Passive scalar transport novyno OpenFOAM Running, Solving & CFD 9 September 6, 2012 06:52
Passive Scalar Andy R FLUENT 0 January 10, 2007 15:49
passive scalar boundaries ultrich CD-adapco 0 July 12, 2005 11:20
starwatch & passive scalar isidro CD-adapco 1 June 24, 2005 23:59
Mixing of a passive scalar Maged Ismail FLUENT 0 June 10, 2005 09:09


All times are GMT -4. The time now is 10:50.