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-   -   Particle Tracking (http://www.cfd-online.com/Forums/flow-3d/119033-particle-tracking.html)

Zerit June 8, 2013 14:09

Particle Tracking
 
Hello All,

I am trying to track sediment movmemnt in Flow-3D so as to picture the incipient movement of the grains. I would be glad if you shove me some idea on how to do it.

I mean aside to the checking the concentration difference.

Thank you,

MuxaB June 12, 2013 11:57

Quote:

Originally Posted by Zerit (Post 432803)
Hello All,

I am trying to track sediment movmemnt in Flow-3D so as to picture the incipient movement of the grains. I would be glad if you shove me some idea on how to do it.

I mean aside to the checking the concentration difference.

Thank you,

You could use mass particles - using the initial particle block or sources, - to track individual sediment grains. The particles would have to have the same properties - size and density, - as the sediment. However, particles do not interact with each other, unlike the real sediment particles.

Zerit June 12, 2013 16:44

Hello MuxaB,

Thank you for your replay. I understand how the particles behave but I have no clue on how to activate it in the program and nothing is mentioned in the user manual/ Flow-3D documentation. Would you be kind enough to shove me some ideas on how to do it in F-3D.

saeedtk June 25, 2013 02:18

hi
it is very easy, go to particle in physics, choose block, define the location of your block, choose diameter and number of particle then ok. choose rho and other properties then run your case.

i hope it helps u

MuxaB July 13, 2013 14:29

Have you figured it out?

MIchael


Quote:

Originally Posted by saeedtk (Post 435718)
hi
it is very easy, go to particle in physics, choose block, define the location of your block, choose diameter and number of particle then ok. choose rho and other properties then run your case.

i hope it helps u


Zerit July 14, 2013 12:54

Right I have activated it and thank you gents.

It is funny though to find that the particles are behaving differently than the packed sediments. The packed sediment deposition and scouring is variable with respect to time & space clearly depicting the stochastic behavior. However with the mass particles, limited number move in a very short period of time and nothing is observed after that. So is it possible that the mass particles are behaving differently?

MuxaB July 14, 2013 17:57

It is certainly possible. Mass particles do not get 'packed' like sediment does. They move according to the force balance - pressure, gravity, drag from fluid.

Quote:

Originally Posted by Zerit (Post 439654)
Right I have activated it and thank you gents.

It is funny though to find that the particles are behaving differently than the packed sediments. The packed sediment deposition and scouring is variable with respect to time & space clearly depicting the stochastic behavior. However with the mass particles, limited number move in a very short period of time and nothing is observed after that. So is it possible that the mass particles are behaving differently?


Zerit July 14, 2013 18:37

but the force balance is also behind the incipient movement of sediment grains even though the local small turbulence may be very chaotic (stochastic).

MuxaB July 16, 2013 18:43

Not quite. Particles are tracked as Lagrangian bodies using the 2nd Newton's law. Sediment is tracked as continuum, so there will be differences. Particles do not interact with each other, only with fluid. For example, particles do not pack and form packed bed.

Quote:

Originally Posted by Zerit (Post 439682)
but the force balance is also behind the incipient movement of sediment grains even though the local small turbulence may be very chaotic (stochastic).


Zerit July 19, 2013 08:15

The results along with your explanation clearly depicts that the use particles in place of sediment to understand the starting movement of sand grains is impossible.

JBurnham July 29, 2013 17:19

If you wish to study forces acting on a single particle, consider using 'general moving object' physics. The scale of the model will be very small so that one or two individual grains are resolved. Then you can look at angularity, resting orientation, etc.


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