[Emy]

Hello everyone!

I am running an LES in fluent to study particle deposition in a bend so here are the steps I followed:

1- run a steady K-e flow in a simple tube with periodic BC
2-after convergence I extract the instantaneous fluctuations using solve/initialize/init-turb-vel-fluctuations
3-switch to LES after convergence I export the velocity profile at the outlet cross-section to use as a velocity profile for the bend inlet
4- I imported the velocity profile for the bend inlet, and run my LES for the bend pipe
5- after convergence I enabled the DPM model to study the particle deposition

6- I compute the deposition efficiency

The problem is that the number of deposited particles is very small, I need to get a deposition efficiency of 10% instead I get 0.003% !!
the diameter of the particle I used is 2micrometer, the deposition of that range of particles depends on turbulent fluctuations so I think that the flow fluctuations are not well modeled!

for the bend inlet BC, I used the no perturbation option, is that the problem? because I read in Fluent manual that :

"no perturbation means: The stochastic components of the flow at the velocity-specified inlet boundaries are neglected if the No Perturbations option is used. In such cases, individual instantaneous velocity components are simply set equal to their mean velocity counterparts. This option is suitable only when the level of turbulence at the inflow boundaries is negligible or does not play a major role in the accuracy of the overall solution."

Any guidelines please, this is my first time using unsteady flow and LES!

Thank you!