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

Droplets breakup

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

Reply
 
LinkBack Thread Tools Display Modes
Old   December 10, 2002, 15:09
Default Droplets breakup
  #1
Julie Polyakh
Guest
 
Posts: n/a
Hi,

Does anybody have successful experience modeling droplets breakup with STAR-CD?

Regards,

Julie
  Reply With Quote

Old   December 11, 2002, 03:16
Default Re: Droplets breakup
  #2
Ossi
Guest
 
Posts: n/a
It depends on how you define "successful"...

  Reply With Quote

Old   December 11, 2002, 05:58
Default Re: Droplets breakup
  #3
Julie Polyakh
Guest
 
Posts: n/a
I want the computations to agree with experiment. (Now you will ask how do I define "agree"?)
  Reply With Quote

Old   December 11, 2002, 06:25
Default Re: Droplets breakup
  #4
Ossi
Guest
 
Posts: n/a
We have simuleted drops in diesel engines as well as in constant volume bombs. The constant volume bomb computations have been compared with experiments done in the same conditions (spray penetration, drop SMD, spray width and spray shape).
  Reply With Quote

Old   December 11, 2002, 14:08
Default Re: Droplets breakup
  #5
Julie Polyakh
Guest
 
Posts: n/a
Have you calculated drops breakup? I don't see that it works.

In general, I have problems with drops trajectory. It seems like the drag coefficient is too small.

Another question is cell dimensions. Can you give me specific example of cell dimensions from your model?
  Reply With Quote

Old   December 12, 2002, 04:28
Default Re: Droplets breakup
  #6
Ossi
Guest
 
Posts: n/a
I assume you are doing transient simulations because you are trying to breakup droplets. I have not observed problems in drop drag. In constant volume bomb simulations I am typically using cylindrical grid and the cell size is roughly 1mm in every direction near the nozzle. Gradually the cell size is getting bigger when moving away from the nozzle location.
  Reply With Quote

Old   December 12, 2002, 05:02
Default Re: Droplets breakup
  #7
Julie Polyakh
Guest
 
Posts: n/a
Hi Ossi,

I am performing steady-state simulation. There are nothing said about break-up model apliciability with simulation types. Moveover, they use the Reitz breakup in Tutorial 2.3 in steady-state calculation.

Can you explain the meaning of Droplet Trajectory Max File Size(MB) and of Maximum Tracking Time values, please? How one determinates their values and how do they influence the solution?

Thank you,

Julie
  Reply With Quote

Old   December 12, 2002, 05:21
Default Re: Droplets breakup
  #8
Ossi
Guest
 
Posts: n/a
I think one cannot use the droplet collision model for steady-state runs, sorry about that.

Max file size is the max allowed file size of the case.trk file, and max tracking time will ensure that if a drop for some reason will go to a never-ending loop, it will not be tracked more than the specified time.
  Reply With Quote

Old   December 12, 2002, 05:36
Default Re: Droplets breakup
  #9
Julie Polyakh
Guest
 
Posts: n/a
I was talking about droplets breakup (not droplets collision) model.

If I set max .trk file size smaller than it really is, what happens then?
  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
Droplet Breakup Vinod Dhiman FLUENT 1 October 22, 2010 03:11
Another breakup model Jay, Choi CD-adapco 5 January 13, 2010 14:36
DPM - breakup postprocessing bohis FLUENT 0 May 6, 2008 02:58
jet breakup basics alex FLUENT 1 January 29, 2008 04:09
breakup models kiao Main CFD Forum 1 May 11, 2005 13:47


All times are GMT -4. The time now is 12:12.