Hello,

I am using Fluent 3d for simulating the trajectories of particles in a detention tank. The particles are assumed to be a discrete phase in a turbulent water flow. So, I am using the Discrete Random Walk Model in order to take into the effect of the turbulence on the particle motion.

Each eddy is defined by a Gaussian distributed random velocity fluctuation u', v', and w'. But near the bed, the velocity fluctuation is not Gaussian anymore (especially the vertical velocity) (because of bursts). So, I would like to define my own distributions for the velocity fluctuations near the bed.

Does someone know how I can access these distributions and modify them in an User Defined Function ? I would like to keep the Gaussian distribution when the wall unit, y*, is superior to a threshold value, and use my own distributions when y* is inferior to this value. Does someone have another idea to model the influence of burst on particle motion ?

Matthieu

[vincenzolights]

Originally Posted by Matthieu
;148020

Hello,

I am using Fluent 3d for simulating the trajectories of particles in a detention tank. The particles are assumed to be a discrete phase in a turbulent water flow. So, I am using the Discrete Random Walk Model in order to take into the effect of the turbulence on the particle motion.

Each eddy is defined by a Gaussian distributed random velocity fluctuation u', v', and w'. But near the bed, the velocity fluctuation is not Gaussian anymore (especially the vertical velocity) (because of bursts). So, I would like to define my own distributions for the velocity fluctuations near the bed.

Does someone know how I can access these distributions and modify them in an User Defined Function ? I would like to keep the Gaussian distribution when the wall unit, y*, is superior to a threshold value, and use my own distributions when y* is inferior to this value. Does someone have another idea to model the influence of burst on particle motion ?

Matthieu

Hello Matthieu, I know this topic is old but have you solved this problem?