dpm modeling

milad653279 · December 3, 2012, 04:12

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

barzin · December 3, 2012, 07:22

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, 11:34

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, 04:25

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, 07:57

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, 11:29

Hi mate,

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

hityangsir · December 8, 2012, 04:33

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, 06:05

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

Payam89 · January 23, 2013, 06:00

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, 10:01

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, 06:33

Quote:

Originally Posted by barzin

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

December 3, 2012, 04:12	dpm modeling	#1
milad653279 Member Milad Setareh Join Date: Oct 2012 Location: Tehran, Iran Posts: 35 Rep Power: 13	hi what is difference between steady particle tracking and unsteady particle tracking?

December 3, 2012, 07:22		#2
barzin Member barzin Join Date: Jan 2011 Posts: 33 Rep Power: 15	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 kamyab likes this.

January 23, 2013, 06:00	Dpm	#9
Payam89 Member payamfadaei Join Date: Oct 2012 Location: Mashhad/Iran Posts: 32 Rep Power: 13	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

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December 5, 2012, 11:34		#3
milad653279 Member Milad Setareh Join Date: Oct 2012 Location: Tehran, Iran Posts: 35 Rep Power: 13	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, 04:25		#4
barzin Member barzin Join Date: Jan 2011 Posts: 33 Rep Power: 15	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, 07:57		#5
hityangsir New Member Y. Yang Join Date: Mar 2010 Location: Miami, United States Posts: 28 Rep Power: 16	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, 11:29		#6
barzin Member barzin Join Date: Jan 2011 Posts: 33 Rep Power: 15	Hi mate, Sorry I did not get the question. Can u please shed more light?

December 8, 2012, 04:33		#7
hityangsir New Member Y. Yang Join Date: Mar 2010 Location: Miami, United States Posts: 28 Rep Power: 16	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, 06:05		#8
barzin Member barzin Join Date: Jan 2011 Posts: 33 Rep Power: 15	Don't worry, I got you now, This mean the whole particle trajectory!

January 28, 2013, 10:01		#10
barzin Member barzin Join Date: Jan 2011 Posts: 33 Rep Power: 15	Hey Payam, You need to have a deeper look in DPM and injection panel! I'm sure you'll able to find it.