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

Near wall particles

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

Reply
 
LinkBack Thread Tools Display Modes
Old   September 1, 2000, 03:24
Default Near wall particles
  #1
Staffan
Guest
 
Posts: n/a
Hi,

I'm simulating particle flow in a combustion chamber. My particles are of the sizes: 0.0001m, 1e-5m and 1e-6m. The problem is that small particles hits the walls as often as the bigger ones. In reality the small ones should follow the gasflow. How does fluent calculate near wall threatment of particles? a.) Is a particle considerd as trapped (escaped or reflexed) when it enters the cell next to the wall or when the particle actually hits the wall? b.)Does the mesh size near the boundaries influence the results of the near wall threatment of particles?

Thanks, Staffan
  Reply With Quote

Old   September 4, 2000, 12:38
Default Re: Near wall particles
  #2
Rüdiger Schwarze
Guest
 
Posts: n/a
I've got the same unphysical results in a similar problem. I think that the drw model is responsible for these errors. The particle obtains a fluctuating velocity u' in the free flow field and an eddy life time which is much more longer the the flying time through the boundary layer.
  Reply With Quote

Old   October 2, 2000, 08:47
Default Re: Near wall particles
  #3
Hesham El-Batsh
Guest
 
Posts: n/a
I think the turbulence model has great effect. For example, the standard k-e model is a fully turbulent model and generates high turbulent knietic energy which affects the particle fluctuating velocity used in RWM and finally increases the number of particles hitting the surface. To accurately predict particle dispersion near the wall using RWM, low Reynolds number models are required. The other possibility is to use damping functions in the near wall region. One of the damping functions can be found in this reference: Wang, Y. and James, P. W. "On the Effect of Anisotropy on the Turbulent Dispersion and Deposition of Small Particles" International Journal of Multiphase flow, v. 25, pp. 551-558, 1999
  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
tmerge utility creates unwanted interface/walls comes in the final mesh dinesh2n@gmail.com OpenFOAM Other Meshers: ICEM, Star, Ansys, Pointwise, GridPro, Ansa, ... 11 January 20, 2012 06:23
Patches for OpenFOAM 1.7 on MacOS X gschaider OpenFOAM Installation on Windows, Mac and other Unsupported Platforms 101 September 21, 2011 05:37
Urgent help needed plz! No. of particles in surface injection ajkratos FLUENT 4 March 22, 2011 11:32
how to determine the number of particles injected. welch FLUENT 1 November 1, 2005 05:11
Quick Question - Wall Function D.Tandra Main CFD Forum 2 March 16, 2004 04:29


All times are GMT -4. The time now is 12:20.