ESEL Paper Review_201201003

By Hong Guo

Mail: hongguo@gist.ac.kr

Phone: (+82) (0)10 82276568

1, Title and Author

Title: Numerical simulation of sedimentation of micro particles using the dicrete particle method

Journal: Particuology

Authors:

Chane-Yuan Yang a,*, Yulonkg Ding a, Dave York b, Walter Broeckx b

a Institute of Particle Science and Engineering , University of Leeds, Leeds LS2 9Jt, UK

b Procter and Gamble Newvastle Technical Centre, Newcastle-upon-Tyne NE12 9TS, UK

2. Summary of Paper

This paper reports some preliminary modeling results of mono-dispersed micro particles settling in aqueous suspensions under various conditions. The results show the short time dynamics of fluid phase, which has a similar order of magnitude to the particle phase. In addition, preliminary analyses of the results have been carried out on the evaluation of particle settling based on a newly proposed parameter, local normalized volume fraction.

2.1 Results

The CFD simulation was completed to investigate the effect of particle physical properties (density and size), liquid properties (viscosity, liquid compositions), and particle concentration on the sedimentation behavior.

2.1 Evolution of fluid field

The author changed of the fluid flow field at y=1cm as a function of time under condition and found that settling of particles causes local motion of the fluid. The motion of fluid in the bottom part of the vessel is due to the backflow of liquid in the opposite direction to particle settling. 0.01s short time dynamic was observed. In addition, the magnitude of the fluid velocity in the vessel can be of a similar order to that of the particles, indicating that short time dynamics of the fluid can exert significant effect on particle motion

2.2 Evaluation of spatial distribution of particles and solids velocity

As the number of particlesi relatively small, partilces settling completely at the bottom of the vessel and it also suggests particle structuring with high voidage in some regions, for which gravitation-induced instabilities many play a role

2.3 Local normalized volume fraction (LNVF)

To quantify the particle concentration on the both of upper and lower part of vessel, the author import a new parameter called local normalized volume fraction to describe the local particle concentration in the sub-zones. As a results, the duration of the approximately constant LNVF depends on the positions, settling time, and properties of both fluid and particles.

3. Contribution:

The simulation results well depict the evolution of particle velocity and concentration distribution, and show at the same time the short time dynamics of fluid phase, which has a similar order of magnitude to the particle phase. We could find that even though the work is preliminary, it is firstly us the proposed computational framework to model particle settling in liquid and validate the modeling experimentally. Hopefully this paper could help the sedimentation case study.

4. Author information:

Email: schaeffer.blake@epa.gov