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-   -   Lagrangian Tracking in CFX (Multiphase flow) (http://www.cfd-online.com/Forums/cfx/103330-lagrangian-tracking-cfx-multiphase-flow.html)

 inotin June 17, 2012 16:45

Lagrangian Tracking in CFX (Multiphase flow)

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!

 ghorrocks June 17, 2012 19:30

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.

 inotin June 17, 2012 19:39

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.

 ghorrocks June 17, 2012 19:58

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.

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