# Discrete Phase Model

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 September 20, 2011, 05:42 Discrete Phase Model #1 New Member   vittal Join Date: Aug 2011 Posts: 10 Rep Power: 14 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

 September 20, 2011, 11:16 #2 Member   Ronald A. Lau Join Date: Jul 2009 Location: Chicago Posts: 30 Rep Power: 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. liangerscu likes this.

 September 21, 2011, 00:07 Discrete Phase Model #3 New Member   vittal Join Date: Aug 2011 Posts: 10 Rep Power: 14 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.

 October 28, 2014, 08:45 Vof-dpm #4 Member   azna Join Date: Nov 2012 Posts: 30 Rep Power: 13 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

October 28, 2014, 10:07
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vittal
Join Date: Aug 2011
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Quote:
 Originally Posted by azna 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.