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-   -   dpm modeling (http://www.cfd-online.com/Forums/fluent/110056-dpm-modeling.html)

milad653279 December 3, 2012 05:12

dpm modeling
 
hi
what is difference between steady particle tracking and unsteady particle tracking?

barzin December 3, 2012 08:22

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 1e-06 and so on).

Hope that helps

milad653279 December 5, 2012 12:34

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.:(:(

barzin December 6, 2012 05:25

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.

hityangsir December 7, 2012 08:57

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

barzin December 7, 2012 12:29

Hi mate,

Sorry I did not get the question. Can u please shed more light?

hityangsir December 8, 2012 05:33

I am sorry for that. What I dont understand is that "Lagrangian trajectory integration time is from t=0 to t=inf"?

barzin December 8, 2012 07:05

Don't worry, I got you now, This mean the whole particle trajectory!

Payam89 January 23, 2013 07:00

Dpm
 
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

barzin January 28, 2013 11:01

Hey Payam,

You need to have a deeper look in DPM and injection panel! I'm sure you'll able to find it.

Payam89 January 29, 2013 07:33

Dpm
 
Quote:

Originally Posted by barzin (Post 404530)
Hey Payam,

You need to have a deeper look in DPM and injection panel! I'm sure you'll able to find it.

But when I change the air by Water it doesn't work.My problem is "Fe" particles which is immersed in Water.But I'm not sure that Dpm is the model I should use!

Thanks


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