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Old   September 20, 2011, 05:42
Default Discrete Phase Model
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vittal
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I have come across a problem pertaining to Discrete Phase Model. In this problem, we are defining water droplets of uniform dia. of 0.48 mm as 'droplet' discrete phase (surface injection) where as the continuous phase is water vapour. There is a mesh of 0.28 mm dia wires and the mesh pitch is 0.58 mm. The flow takes place across this wire mesh.

The outcome of the simulation shows that these droplets penetrate even though the distance between the two wires is less than the droplet diameter. When changed the discrete phase to 'inert' with ash as material while maintaining diameter, velocity and total mass flow rate, we still find the droplets penetrating the narrow passage between the adjecent wires, which may not be the case in actual. The ash particles are expected to be filtered or at least they should show significant slowing down.

Can anyone help how to set this problem
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Old   September 20, 2011, 11:16
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Ronald A. Lau
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The discrete phase model only uses the droplet diameter for lifetime.

The droplet is treated as a point in the continuous phase, and will pass through your mesh no matter how big it is.

If the trajectory is such that it contact the wall of your mesh, it could be 'trapped' or reflect off of it depending on the BC of the wall.
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Old   September 21, 2011, 00:07
Default Discrete Phase Model
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vittal
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Thank you for giving reply

Sir, then how can take the diameter into consideration.I am giving Reflect boundary condition to the mesh (wires). Most of the particles are passing through the mesh which is not the actual case.
Do you have any tutorial related to DPM (Discrete Phase Model) (other than the tutorial which was given in the Fluent software).If you have means can you share it with me.

Waiting for your reply.
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Old   October 28, 2014, 09:45
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Hi ,

I am using VOF-DPM approach to model air bubbles into the lake, I'm getting higher terminal velocity than using eulerian approach, I specified air velocity in the boundary condition ( Inlet Velocity) and also in the DPM part.
I was wondering can somebody help me on this ? ( is there any similar papaer or tutorial for this case?

Thanks a lot
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Old   October 28, 2014, 11:07
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Quote:
Originally Posted by azna View Post
Hi ,

I am using VOF-DPM approach to model air bubbles into the lake, I'm getting higher terminal velocity than using eulerian approach, I specified air velocity in the boundary condition ( Inlet Velocity) and also in the DPM part.
I was wondering can somebody help me on this ? ( is there any similar papaer or tutorial for this case?

Thanks a lot
Hi,
I have done similar work but in a tank with air bubble induced, at the bottom of the tank, using VOF method.I didnt exactly observed terminal velocity but I found out that velocity is conserved at the exit point.
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