CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT > Fluent UDF and Scheme Programming

Using UDF to alter particle size

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 18, 2005, 05:05
Default Using UDF to alter particle size
  #1
Tumppi
Guest
 
Posts: n/a
Hello everybody

Kind of newbie quetion here. I'm trying to alter the particle size (diameter) with UDF in fluent. I made a little code for testing purposes and interpreted it and then defined an injection which uses this UDF. But when I dislay particle track, the diameter doesn't change. I used DEFINE_DPM_LAW as define function. If someone could help me it would be great.
  Reply With Quote

Old   May 18, 2005, 14:45
Default Re: Using UDF to alter particle size
  #2
Allan Walsh
Guest
 
Posts: n/a
I assume you are manipulating P_DIAM(p). Print out P_DIAM(p) in your UDF, before and after manipulating it. Depending on particle type (i.e. inert, combusting, etc.) FLUENT could reset it somewhere else.

Good luck.
  Reply With Quote

Old   May 23, 2005, 08:50
Default Re: Using UDF to alter particle size
  #3
Tumppi
Guest
 
Posts: n/a
Well seems thet I'm dooing something really wrong. When I put printf lines to see what happens I only get 0 values for P_DIAM(p) and its only reported once at the start.

If someone can guide me to right direction that would be nice.
  Reply With Quote

Old   May 23, 2005, 12:13
Default Re: Using UDF to alter particle size
  #4
Allan Walsh
Guest
 
Posts: n/a
Do the values for P_DIAM(P) match up with what FLUENT shows if you do a step-by-step particle tracking? They should.

If it is only getting to your print statement once, it could be that FLUENT is only using your UDF once and then setting the particle to use the next law. Can you check that.

  Reply With Quote

Old   May 25, 2005, 04:21
Default Re: Using UDF to alter particle size
  #5
Tumppi
Guest
 
Posts: n/a
I think I found the answer why I cant get the UDF to work. If you read part 19.9.3 Particle Types at the manual you can see that only law 1 is active when one uses inert particle (which I did). So I gues that I have to use a droplet particle type to get my UDF to work, am I right?

Thank you for your help so far Allan.
  Reply With Quote

Old   May 27, 2005, 04:23
Default Re: Using UDF to alter particle s. Problem Solved
  #6
Tumppi
Guest
 
Posts: n/a
Well I solved the problem and got it to work with inert particle, I had selected wrong law from the custom laws panel at injection properties. When I put my custom law as Law 1 I got it to work.

Thanks for help.
  Reply With Quote

Old   April 7, 2011, 11:17
Default
  #7
New Member
 
fabien tagada
Join Date: Oct 2010
Posts: 5
Rep Power: 16
tagada is on a distinguished road
Hello Tumppi,

I'm very interested to have a look on your UDF, I'm also trying to alter the particle size with UDF an,d it doesn't work.
This is my code:

#include "udf.h"
#include "dpm.h"

DEFINE_DPM_LAW (diam_particle, p, ci)
{
/* compute new particle diameter */
P_DIAM(p) = 6*pow((0.015/2*0.7*1000.0*9.81)* 0.000300*P_POS(p)[0],1/3);
}
Thank you
tagada is offline   Reply With Quote

Old   February 28, 2019, 09:27
Default UDF to consider the particle size in DPM
  #8
Member
 
Liliana de Luca Xavier Augusto
Join Date: Feb 2013
Posts: 68
Rep Power: 13
liliana is on a distinguished road
Hi all,

I am simulating a situation where I have a particle travelling in a fluid. The gap where the fluid flows is too small, and the particle size became important in this case. Does anyone know how can I use an UDF to consider the particle size?

I would be an UDF to make the collision between the particle and the boundary when the distance between the "point" (particle in DPM) is equal or smaller than the diameter of the particle.

Thanks!
liliana is offline   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
UDF for a field size spring FLUENT 0 May 11, 2010 10:02
SPH particle vs. real fragment size Katarina FLUENT 0 April 8, 2009 10:48
HELP! HELP! For udf of particle body force!!!! zhaoh FLUENT 0 February 5, 2007 05:10
udf about particle concentration--who can help me? zhaoh FLUENT 1 January 17, 2007 12:46
Help: UDF of "particle body force" !!! zhaoh FLUENT 3 January 16, 2007 21:17


All times are GMT -4. The time now is 10:39.