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December 3, 2012, 05:12 
dpm modeling

#1 
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milad
Join Date: Oct 2012
Posts: 33
Rep Power: 5 
hi
what is difference between steady particle tracking and unsteady particle tracking? 

December 3, 2012, 08:22 

#2 
Member
barzin
Join Date: Jan 2011
Posts: 33
Rep Power: 7 
Hi Milad,
Well the difference is the same as the difference between steady state solution and transient solution. In Steady particle tracking the entire particle trajectory is computed until the solution gets converged. More mathematically, the Lagrangian trajectory integration time is from t=0 to t=inf. However in unsteady particle tracking, the Lagrangian integration time is between the assign values (say t=0 to 1e06 and so on). Hope that helps 

December 5, 2012, 12:34 

#3 
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milad
Join Date: Oct 2012
Posts: 33
Rep Power: 5 
Hi Barzin
thanks a lot. I don't understand. I think that in steady particle tracking derivative time is zero so means d/dt=0 therefore velocity is constant and it's meaningless because of Lagrangian approah is always unsteady. so why dpm modeling in fluent has steady particle tracking? I don't understand this contradiction. please explain it.:(:( 

December 6, 2012, 05:25 

#4 
Member
barzin
Join Date: Jan 2011
Posts: 33
Rep Power: 7 
Milad jan
Why do you think it's meaningless? plus it doesn't mean that particle velocity is constant through out the trajectory. imagine that you solve a continuous flow in a pipe. In steady calculation if the initial velocity at inlet is constant, the velocity will decay along the pipe. I think you can adapt this to a particle trajectory calculation. 

December 7, 2012, 08:57 

#5 
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Y. Yang
Join Date: Mar 2010
Location: Miami, United States
Posts: 28
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His Barzin, I have a question too, assume that in a unseady problem, in the steady particle tracking, only the entire particle trajectory is computed until the end of the calculation ? that does not make sense


December 7, 2012, 12:29 

#6 
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barzin
Join Date: Jan 2011
Posts: 33
Rep Power: 7 
Hi mate,
Sorry I did not get the question. Can u please shed more light? 

December 8, 2012, 05:33 

#7 
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Y. Yang
Join Date: Mar 2010
Location: Miami, United States
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I am sorry for that. What I dont understand is that "Lagrangian trajectory integration time is from t=0 to t=inf"?


December 8, 2012, 07:05 

#8 
Member
barzin
Join Date: Jan 2011
Posts: 33
Rep Power: 7 
Don't worry, I got you now, This mean the whole particle trajectory!


January 23, 2013, 07:00 
Dpm

#9 
Member

Hi Dears
I have a air flow which enter a cavity and exit it,I want to add some particles to the flow which has a lift and drag(I'm going to change their direction by magnetic fields)...How can I determine the diam and number of particles,velocity,permaebility and density and.... In which panel this settings exist?? Thanks a lot 

January 28, 2013, 11:01 

#10 
Member
barzin
Join Date: Jan 2011
Posts: 33
Rep Power: 7 
Hey Payam,
You need to have a deeper look in DPM and injection panel! I'm sure you'll able to find it. 

January 29, 2013, 07:33 
Dpm

#11  
Member

Quote:
Thanks 

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