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

residence time distribution

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   December 6, 2005, 03:49
Default residence time distribution
  #1
markus
Guest
 
Posts: n/a
Hi... I want to use a Particle Tracking approach to obtain the RTD of a vessel based on a steady state simulation. When doing this the mean residence time gets way to high. I used small particles with a density of 1 and added turbulent dispersion. I am not sure about adding additional forces.

Any hints to the problem or another suggestions on how to obtain a "lagrangian" residence time distribution?

  Reply With Quote

Old   December 6, 2005, 09:58
Default Re: residence time distribution
  #2
Martin
Guest
 
Posts: n/a
it it much easier to implement an Additional Variable "RDT" with unit [s] and transport equation. RDT is set "0" at all inlet.

Then you create a subdomain "RDT sub" over all and impement a source for RTD with 1 [s/s]. Now RDT will become greater with resident time.

bye martin

  Reply With Quote

Old   December 6, 2005, 10:46
Default Re: residence time distribution
  #3
markus
Guest
 
Posts: n/a
I aready tried the implementation of an additional Variable RTD. Analysing the spatial distribution of RTD at the outlet of my reactor gives the right mean residence time, but just a rough approximation of the distribution (too coarse grid??) and a too narrow distribution (probably due to numerical diffusion effects). That why this approach seems not very powerful to me.

markus
  Reply With Quote

Old   December 8, 2005, 02:47
Default Re: residence time distribution
  #4
Martin
Guest
 
Posts: n/a
your particle tracking can't be better than your grid - so this would be the problem with your results. Diffusion effects shouldn't be if you use ADVECTION SCHEME: high res

  Reply With Quote

Old   December 19, 2005, 06:52
Default Re: residence time distribution
  #5
zhixin huang
Guest
 
Posts: n/a
Hi... How to get residence time distribution in cfx-post? thanks.
  Reply With Quote

Old   December 19, 2005, 12:48
Default Re: residence time distribution
  #6
markus
Guest
 
Posts: n/a
I'd run a transient simulation with a frozen flowfield where you solve a transport equation for an additional variable (scalar). Use pulse or step input and then monitor the massflow average of this quantity over time at the outlet.

markus
  Reply With Quote

Reply


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
TimeVaryingMappedFixedValue irishdave OpenFOAM Running, Solving & CFD 32 June 16, 2021 07:55
Pathline colored by time = residence time pkleb FLUENT 1 February 26, 2021 09:00
Superlinear speedup in OpenFOAM 13 msrinath80 OpenFOAM Running, Solving & CFD 18 March 3, 2015 06:36
How to get residence time distribution? bigfans FLUENT 0 April 27, 2009 10:39
Residence Time Distribution rajeev FLUENT 11 July 26, 2001 14:49


All times are GMT -4. The time now is 04:54.