# Lagrangian Tracking in CFX (Multiphase flow)

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 June 17, 2012, 16:45 Lagrangian Tracking in CFX (Multiphase flow) #1 New Member   Join Date: Jun 2012 Posts: 2 Rep Power: 0 Hi all, I would be grateful if you answer my question. As far as I know there are 2 main approaches of multiphase modelling: Euler-Euler when particle phase is assumed continuos and Euler-Lagrangian, when each particle is treated as single. In CFX help it is said that in case of Lagrnagian particle tracking each eddy particle enters has some fluctuating velocity due to turbulence which is added to mean velocity. And that resulting velocity affects particle movement. But what about Navier-Stokes equations for each eddy in this case? are they ignored? or in other words: Is fluid phase is calculated using Eulerian approach if we use lagrangian particle tracking in CFX? or it is calculated as it is said above? Thank you!

June 17, 2012, 19:30
#2
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Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
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Lagrangian particle tracking does not consider "eddy particles" (what ever they are). It considers true solid particles are moved about in the flow through drag forces and other forces.

Quote:
 But what about Navier-Stokes equations for each eddy in this case? are they ignored?
Again, I have no idea what you mean by eddies. Lagrangian particle tracking has got nothing to do with eddies.

 June 17, 2012, 19:39 #3 New Member   Join Date: Jun 2012 Posts: 2 Rep Power: 0 But all these forces require defined speed of fluid phase. What i mean is how fluid phase is treated ( or how is it described) and how we get that speed of fluid phasein CFX if lagrangian particle tracking applied? Thank you.

 June 17, 2012, 19:58 #4 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 12,638 Rep Power: 98 This is all in the documentation. The fluid phase is modelled with the NS equations, and the particle phase by particle kinematics. The particle phase is coupled to the fluid phase using source terms.

 Tags cfx, lagrangian, multiphase, particle

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