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

Particle residence time!!

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

Reply
 
LinkBack Thread Tools Display Modes
Old   June 12, 2008, 00:03
Default Particle residence time!!
  #1
Kandy
Guest
 
Posts: n/a
Hello there,

I want to calculate the age of air in a volume.

will, calculating the particle residence time give me a solution on this. if so can you please tell me how i can do it.

Please let me know.

Thanks Kind Regards Kandy
  Reply With Quote

Old   June 12, 2008, 00:35
Default Re: Particle residence time!!
  #2
Allan Walsh
Guest
 
Posts: n/a
Try pathlines colored by particle residence time. I have used this to visually get an estimate of residence time without any text summary statistics.
  Reply With Quote

Old   June 12, 2008, 04:55
Default Re: Particle residence time!!
  #3
novice
Guest
 
Posts: n/a
Hi,

I think you have to define particle injections using Discrete Phase Model. Using DPM u can define particle injections from a surface(for ex: from inlet).

best regards

  Reply With Quote

Old   June 12, 2008, 17:07
Default Re: Particle residence time!!
  #4
red lemon
Guest
 
Posts: n/a
you need not use DPM. You can use a user defined scalar that is seeded into the domain. Just solve your steady case then setup the UDS and solve a few iterations (say 5 or 10) for the UDS. Your support group can provide details of this UDS approach or I can if you cannot obtain.
  Reply With Quote

Old   June 12, 2008, 20:17
Default Re: Particle residence time!!
  #5
kandy
Guest
 
Posts: n/a
Thanks Guys!!

We din't purchase support in the package.

Please type me in the details in your spare time. i will be highly obliged.

With Kind Regards

Kandy
  Reply With Quote

Old   June 13, 2008, 04:18
Default Re: Particle residence time!!
  #6
novice
Guest
 
Posts: n/a
Hi Red lemon,

Can u please send me the procedure u worte. It will be interesting for me how to do this task using a udf.

Regards

  Reply With Quote

Old   June 13, 2008, 04:31
Default Re: Particle residence time!!
  #7
Fluent_guy
Guest
 
Posts: n/a
dear sir,

yes, pls tell us the procedure for the Eulerian-Eulerian model. I mailed Fluent.Inc many times, but without any reply from them. They refer to Solution No. 619. However, this method is not suitable for RTD measurement of multiple dispersed phases. (if anyone requires the solution 619, i can paste the same here) red-lemon,we are all hoping for your reply.

thanks and regards.
  Reply With Quote

Old   June 13, 2008, 08:32
Default Re: Particle residence time!!
  #8
red lemon
Guest
 
Posts: n/a
ok I will post use of uds for residence time. It is the same method employed in Airpak that uses Fluent but in this case it is done in the GUI in a simpler format and Fluent's method is a bit confusing. Bear with me as I recover details.
  Reply With Quote

Old   June 17, 2008, 13:51
Default Re: Particle residence time!!
  #9
red lemon
Guest
 
Posts: n/a
OK here you go.

Convert this text to a *.c file then compile as usual and follow notes to hook in. Then solve for scalar only and post process.

/* Diffusivity for mean age of air

is solved using a user-defined scalar. This

calculation can be performed after the normal

problem has already been solved ... just turn off

all of the previous equations being solved for

and activate solution of the user-defined scalar-0

equation. Make sure to select

- mean_age_diff as the uds diffusivity in the materials panel

- mass flow rate as the uds flux function

- mean_age_source as the uds volumetric source term in

all fluid regions

Use a journal like this to do that in F63 :

def bc fluid fluid-1 n y 0 0 0 0 0 0 0 1 n y "mean_age_source" n y 0 0 0 0 0 0 n n n

def bc fluid fluid-2 n y 0 0 0 0 0 0 0 1 n y "mean_age_source" n y 0 0 0 0 0 0 n n n

def bc fluid fluid-3 n y 0 0 0 0 0 0 0 1 n y "mean_age_source" n y 0 0 0 0 0 0 n n n

etc

- set uds-0 scalar values = 0.0 at all inlets and outlets

mean age of air calculations do not require

any energy, radiation, or species transport

calculations to have been performed

*/

/************************************************** *****/

#include "udf.h"

#include "prop.h"

DEFINE_DIFFUSIVITY(mean_age_diff, c, t, i)

{

return C_R(c,t)*2.88e-05+C_MU_EFF(c,t)/0.7;

}

DEFINE_SOURCE(mean_age_source, c, t, dS, eqn)

{

dS[eqn]=0;

return C_R(c,t);

}

  Reply With Quote

Old   June 25, 2008, 11:03
Default Re: Particle residence time!!
  #10
learning_never_ends
Guest
 
Posts: n/a
Hi red lemon,

This is for a single-phase flow..but what should we do if we have multi-phase flow and need to claculate the residence time of the dispersed phases only ?

Thank you.
  Reply With Quote

Old   June 25, 2008, 21:13
Default Re: Particle residence time!!
  #11
kandy
Guest
 
Posts: n/a
Hi red Lemon,

Thank you very much.

I was on holidays. will try this.

Thank you one again.

Regards

Kandy

  Reply With Quote

Old   October 20, 2011, 06:39
Default Hi to every one...I want know How to post process the Mean age of air in fluent.. Ple
  #12
New Member
 
Hanumanth
Join Date: Aug 2009
Posts: 6
Rep Power: 8
p08tm007 is on a distinguished road
Hi to every one...I want know How to post process the Mean age of air in fluent.. Please any one can help regarding this...Thanks in advance ....


Quote:
Originally Posted by red lemon
;151570
OK here you go.

Convert this text to a *.c file then compile as usual and follow notes to hook in. Then solve for scalar only and post process.

/* Diffusivity for mean age of air

is solved using a user-defined scalar. This

calculation can be performed after the normal

problem has already been solved ... just turn off

all of the previous equations being solved for

and activate solution of the user-defined scalar-0

equation. Make sure to select

- mean_age_diff as the uds diffusivity in the materials panel

- mass flow rate as the uds flux function

- mean_age_source as the uds volumetric source term in

all fluid regions

Use a journal like this to do that in F63 :

def bc fluid fluid-1 n y 0 0 0 0 0 0 0 1 n y "mean_age_source" n y 0 0 0 0 0 0 n n n

def bc fluid fluid-2 n y 0 0 0 0 0 0 0 1 n y "mean_age_source" n y 0 0 0 0 0 0 n n n

def bc fluid fluid-3 n y 0 0 0 0 0 0 0 1 n y "mean_age_source" n y 0 0 0 0 0 0 n n n

etc

- set uds-0 scalar values = 0.0 at all inlets and outlets

mean age of air calculations do not require

any energy, radiation, or species transport

calculations to have been performed

*/

/************************************************** *****/

#include "udf.h"

#include "prop.h"

DEFINE_DIFFUSIVITY(mean_age_diff, c, t, i)

{

return C_R(c,t)*2.88e-05+C_MU_EFF(c,t)/0.7;

}

DEFINE_SOURCE(mean_age_source, c, t, dS, eqn)

{

dS[eqn]=0;

return C_R(c,t);

}
p08tm007 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
partickle-tracks and udf, particle-residence-time Alex FLUENT 0 August 15, 2006 03:46
Particle residence time Philip FLUENT 0 June 16, 2006 03:30
how to get the particle residence time in UDF? welch FLUENT 0 November 17, 2005 20:32
Particle Residence Time Ethan CD-adapco 0 July 29, 2002 14:45
Particle tracks and residence time Bo Jensen CD-adapco 1 January 10, 2002 05:19


All times are GMT -4. The time now is 03:19.