DPM Diameter querry

Mohsin · August 16, 2010, 22:00

I am using DPM surface injection from inlet whose sides are 0.82*0.89 m. But when i inject particles of 10 m diameter still i get the resullt at the outlet. why is it so??? How can a particle enter into a duct having bigger dimensions than the duct? Aren't I supposed to get an error??

Your urgent response will be highly appreciated.

Mohsin

xrs333 · August 16, 2010, 22:37

DPM model is a Euler-Lagrangian multiphase flow model, that is, the discrete phase is considered as particles no matter how big it is, only the trajectory of the centroid is cumputed.

Mohsin · August 16, 2010, 22:43

Thanks for your reply

As far as i know in the langrangian method the particles are tracked while in Eulerian method fixed point is taken and particles are not followed.

Dpm uses Langrangian formulation but How can a trajectory be calculated if the diameter of the particle is larger than the duct in which it is moving? could u please elaborate.

xrs333 · August 16, 2010, 23:00

In real world it is impossible for the diameter of a particle larger than the duct. So, in the computer, if you build a computation model like that, the mistake is brought about by you, not by the computer or the DPM model. You built a wrong model with a improper method.

Mohsin · August 16, 2010, 23:04

ok so i will assign the diameters according to the streams I m sending in. for exapmple for group injection of 5 streams in a duct of 5m, I will assign a diameter starting to end point as 0.1 so that each particle stream has 0.1 diameter and it should remian in the domain. otherwise if i assign a diameter of 0.2 fluent will still calualte it but as u mentioned it would contradict with the real world problem and would have errors.

If i m wrong please let me know. Thanks for your time.

August 16, 2010, 22:00	DPM Diameter querry	#1
Mohsin Senior Member Mohsin Mukhtar Join Date: Mar 2010 Location: South Korea Posts: 249 Rep Power: 17	I am using DPM surface injection from inlet whose sides are 0.82*0.89 m. But when i inject particles of 10 m diameter still i get the resullt at the outlet. why is it so??? How can a particle enter into a duct having bigger dimensions than the duct? Aren't I supposed to get an error?? Your urgent response will be highly appreciated. Mohsin

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August 16, 2010, 22:37		#2
xrs333 Senior Member xrs333 Join Date: Aug 2010 Posts: 125 Rep Power: 16	DPM model is a Euler-Lagrangian multiphase flow model, that is, the discrete phase is considered as particles no matter how big it is, only the trajectory of the centroid is cumputed.

August 16, 2010, 22:43		#3
Mohsin Senior Member Mohsin Mukhtar Join Date: Mar 2010 Location: South Korea Posts: 249 Rep Power: 17	Thanks for your reply As far as i know in the langrangian method the particles are tracked while in Eulerian method fixed point is taken and particles are not followed. Dpm uses Langrangian formulation but How can a trajectory be calculated if the diameter of the particle is larger than the duct in which it is moving? could u please elaborate.

August 16, 2010, 23:00		#4
xrs333 Senior Member xrs333 Join Date: Aug 2010 Posts: 125 Rep Power: 16	In real world it is impossible for the diameter of a particle larger than the duct. So, in the computer, if you build a computation model like that, the mistake is brought about by you, not by the computer or the DPM model. You built a wrong model with a improper method.

August 16, 2010, 23:04		#5
Mohsin Senior Member Mohsin Mukhtar Join Date: Mar 2010 Location: South Korea Posts: 249 Rep Power: 17	ok so i will assign the diameters according to the streams I m sending in. for exapmple for group injection of 5 streams in a duct of 5m, I will assign a diameter starting to end point as 0.1 so that each particle stream has 0.1 diameter and it should remian in the domain. otherwise if i assign a diameter of 0.2 fluent will still calualte it but as u mentioned it would contradict with the real world problem and would have errors. If i m wrong please let me know. Thanks for your time.