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-   -   DPM: accretion and difference between two wall BC's (http://www.cfd-online.com/Forums/fluent/80026-dpm-accretion-difference-between-two-wall-bcs.html)

cactilio86 September 13, 2010 09:52

DPM: accretion and difference between two wall BC's
 
Hello all,

Let's see if someone can put some light on what Fluent actually does (user's guide has not proved useful in this case).

I have two small questions regarding the use of DPM:

1.- One is related to the accretion model: I have three different surface injections at the same surface, each with a certain (small) mass flow. When I compute the (surface) integral of the accretion in ALL wall surfaces, then the results do not make any sense: I find that the total deposition per second is about two orders of magnitude larger than the total mass injected (per second). Particles are inert.

2.- Doing some trials, I figured that using the "trap" BC at the wall would result in the same results as using the "reflect" BC with restitution coefficient of 0. I have my hypothesis about why it's not the case: the particle, even if reported as "touching the wall'and hence stripped of all momentum, can be blown away by the local flow. But this means that the position of the particle is not really AT the wall (no-slip BC would make impossible for the particle to be blown away), but somewhere near (next cell centre? ). Can anyone confirm upon this?

Any help is highly appreciated !
Regards


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