0207_Large-eddy simulations of particles sedimentation in a longitudinal sedimentation...

ESEL Paper Review_20130207
By Hong Guo
Mail: hongguo@gist.ac.kr
Phone: (+82) (0)10 82276568
1, Title and Author
Title: Large-eddy simulations of particles sedimentation in a longitudinal sedimentation basin of a water treatment plant
Journal: Chemical Engineering Journal
M.Al-Sammarraee,A.Chan*, S.M. Salim, U.S. Mahabaleswar
Department of Chemical and Environmental Engineering, University of Nottingham (Malaysia Campus), Jalan Broga, 43500 Semenyih, Selangor Darul Ehsan, Malaysia
2. Summary of Paper
In this paper the process of sedimentation of 13 different sizes of particles are simulated. The flow patterns, the particle settling velocities, the effectiveness of the particle removal for the stream and the particle concentrations distributions along the basin are estimated using large-eddy simulations.
3. Results
? Particles: The mixture model simulates phases by solving the momentum, continuity, and energy equations for the mixture, the volume fraction equations for the secondary phases and algebraic expressions for the relative velocities. Particles are injected after the hydrodynamics of the tanks is solved.
? Flow pattern:
? the k-epsilon model ever-predicts the turbulence at the shear zone as in the case of flow past bluff bodyies. The k-epsilon model also fils to resolve flow structures around the particles and the near the bottom with sufficient accuracies.
? Turbulence generated by the lighter particles is small throughout because of its relatively small fluctuations and turbulent kinetic energy.
? Larger-size particles are expected to settle quickly along the basin because of its mass and inertia.
? Particle settling efficiency:
? The impact of gravity on the motion of small particles is weak, whereas I the case of large particles, velocity correlations along the particle trajectories tend to decrease duet to the crossing- trajectory effect and particle motion becomes disengaged from fluid turbulence.
4. Contribution:
The authors did the 3D computational study and the LES study was conducted. This paper is a kind of further study of the Goula’s work. However, the authors applied the LES to cover the weakness of the k-epsilon model for the viscosity
terms. In addition, a different size of the particles’ simulation is also a key point for studying to our future research.
5. Author information:
Email: andy.chan@nottingham.edu.my
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