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-   -   multiphase model (http://www.cfd-online.com/Forums/fluent-multiphase/116057-multiphase-model.html)

tangfl April 12, 2013 01:06

multiphase model
 
hi,
i am not sure whether i need to turn on multiphase model..and what type of multiphase should i choose? Mixture??

My condition is water jet towards the sand domain..and hitting towards the wall (erosion) which surrounded with sand domain.

ghost82 April 12, 2013 02:23

You can use mixture model if sand volume fraction is <0.1; you can also use dpm model to model erosion, there's a fluent tutorial about erosion in 180 degree U-bend.

Daniele

tangfl April 12, 2013 02:39

thanks for repying..


So does my setting correctly as shown below?

phases
Phase 1 = water liquid
phase 2 = sand -granular

cell zone condition
liquid-solid = porous zone - material = mixture
solid = mixture

Regard on cell zone condition is only available only one type (mixture)??

ghost82 April 12, 2013 02:45

Sorry, I haven't read well your problem, sand is not in the water which erodes some surface, but a jet of water erodes a sand surface..I'm not sure about how approaching this type of problem, I think it is more appropriate to use eulerian model; at time=0 patch solid zone with sand volume fraction=1


Daniele

tangfl April 12, 2013 02:48

Anyways, thank for your attention!! :)

tangfl May 29, 2013 02:40

i'm confuse on the Eulerian model on eulerian parameter.
What the different dense discrete phase model and multi fluid vof model??
My sand domain should treated as fluid or discrete phase??

oj.bulmer June 6, 2013 11:15

DDPM involves langrangian tracking of the particles in dispersed material, and it is different from DPM in that, DPM doesn't take into account the effect of volume fraction of the discrete phase in mass/momentum equations. DDPM does take into account.

VOF is used when the volume fraction of the discrete phase is locally very large, such that there is a distinct interface betwee the two phases, eg, large bubbles in slug flow.

If you are specifying sand domain as porous medium, how are you taking into account the erosion? Can you post an image of your domain and boundary conditions?


OJ

tangfl June 6, 2013 12:16

1 Attachment(s)
hi,

From the picture, the three hole(red) is treated as water jet inlet; my outlet, is the top surface of the sand domain. And the green pipe is the cylinder wall (green).

i'm thinking on eulerian model is the most suitable for my condition, and treated my sand as granular flow, packed bed for study on erosion rate of the wall. I patch my sand domain initial volume faction as 1. Are you agree with my setting??

Problems??
1) what turbulent viscosity and intensity should i set?? For this condition, as water flow in sand domain, it may be not so turbulent in sand domain.

2) Can i set the wall pipe material??

3) Can i just assume the wall boundary condition as no slip condition.


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