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Amir.11 February 11, 2020 09:10

An issue on CFD/PBM coupled simulation in fluent?
Hi all,

Iím working on a CFD/PBM problem with only constant particle growth through a laminar flow reactor.

As far as I know, when particle growth is constant and occurs alone (no nucleation, no agglomeration and no breakage), the number of particles at outlet has to be exactly the same as inlet.

However, simulations on laminar flow reactor shows an increase in particle number withn the reactor i.e. there is somehow creation of particle in the reactor specially in near-wall zones.
The number of particles at inlet is N=1.91e14 and at outlet it increases to N=2.55e14.

I tested this issue on an ideal plug flow reactor where there was no velocity profile and the particle number at inlet and outlet were exactly the same.
What I am trying to say is that, I think, the problem is not related to PBM algorithm and it arises when PBM is coupled with CFD.

So the question is what is the mechanism in fluent which makes this problem to occur?

My case study is:
2D-Axi (L=0.1(m) , D=0.006(m)), laminar, Eulerian mixture model, PBM model (Standard Method of Moments).
Boundary conditions: axis, velocity inlet, pressure outlet
Solution Method: Coupled
Spatial Discretization: moment: 2nd order upwind, volume fraction: Quick, Momentum: 2nd order upwind and pressure: Presto.

Any comment would be highly appreciated.

vinerm February 11, 2020 10:14

PBM setup
What are the PBM settings for your case? How many moments are you considering?

I wouldn't expect any effect of coupling on 0th moment.

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