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-   -   Incomplete Particle Tracks (http://www.cfd-online.com/Forums/fluent/44939-incomplete-particle-tracks.html)

Don Parsons June 6, 2007 11:44

Incomplete Particle Tracks
 
I am modeling flow in a vortex sampler and using the DSP to inject particles of 1 to 6 micro-meters. I have read all of the posts I can find about incomplete particle tracks but I still cannot correct the problem. My flow is laminar so i do not enable any of the turbulent options in the DPM. My max number of steps is already 6e5 and I have my length scale set to 1e-12 and I am using the spherical drag law. As far as the numerics my tolerence is set to 1e-5 and max no. refinements is set to 20. Right now I am using the analytic tracking scheme, though I have many incomplete particles with all schemes. I am just wonder if anyone has any sugestions at all as to what my problem could be and if my settings sound reasonable. Thank you very much for all your help.

Prasad Dudhgaonkar June 7, 2007 17:15

Re: Incomplete Particle Tracks
 
The settings for numerics are default and they seem to be alright to begin with. Do you have any specific purpose in mind when keeping length scale very small (which eventually leads to very high number of steps)? May I please know why you feel your case needs no consideration for turbulence? The answers will help me understand your case better. Thanks for presenting an interesting situation.

Don Parsons June 8, 2007 09:07

Re: Incomplete Particle Tracks
 
First, thanks for the reply. I was keeping the length scale very small as I was trying to have the particle tracks update more often for a more accurate solution. Also I am not considering turbulence because the inlet velocity is quite small leading to a small Reynolds number (though I am not 100% sure how to determine the onset of turbulence in a vortex). Honestly as far as the small length scale goes I was struggleing for a soluton to the incomplete tracks and I was trying different things. Do you think that it is possible that the small length scale is causing the incomplete tracks. Thank you again.


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