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-   -   Discrete Phase Model (http://www.cfd-online.com/Forums/fluent/92623-discrete-phase-model.html)

vittal September 20, 2011 05:42

Discrete Phase Model
 
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

ronaldalau September 20, 2011 11:16

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.

vittal September 21, 2011 00:07

Discrete Phase Model
 
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.

azna October 28, 2014 09:45

Vof-dpm
 
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

vittal October 28, 2014 11:07

Quote:

Originally Posted by azna (Post 516318)
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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