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Seminar - Modeling and Simulation of Milling Processes by Prof. Avi Levy
日期:2016 年 08 月 03 日 ( 星期三)
Time:11:00 am – 12:00 pm
Venue:EF305

Abstract:

Milling systems are widely used in many industrial applications although they are operated at very low efficiency. A successful design of milling process has been the goal of many research groups. A novel approach for modeling and simulating particles breakage in bulk solids applications is presented. The model considers empirical comminution functions (material functions) and their implementation in DEM simulations (machine function). The comminution functions include: initial strength distribution, selection function, breakage function and fatigue function.

Fluid flow may influence the milling process or even the main reason for it, e.g., the spiral jet-mill, which is one of the most common comminution systems. Jet-mill performance is mainly affected by a combination of two parallel processes: particle breakage and classification. The ability to design jet mills prior to full scale experiments and to optimize existing systems has long been a goal of designers. In order to optimize the performance of the jet-mill, a combined 3D CFD-DEM simulation was developed to accurately predict the jet-mill behavior. The particles size is decreasing due to breakage in the simulation, just as in the actual process. The breakage forces acting on the particles are affected by particle-particle, particle-walls interactions. As the forces increases, finer particles are formed and attraction forces, such as Van der Waals force (VdW) becomes dominant. The VdW forces cause the fine particles to agglomerate or stick (caking) to the jet-mill walls, and it is gradually affect the milling process. The effect of VdW forces on the milling process was investigated numerically, since it cannot be done in an experimental unit and the predictions of the numerical simulations with and without VdW force were compared with experimental data.

Bio-sketch:

Prof. Avi Levy studied Mechanical Engineering at Ben-Gurion University of the Negev, ISRAEL. He got his Ph.D. in 1995 from the same university. He worked as a research scholar in the above university until 1995 and as a research fellow at Glasgow Caledonian University in the Center for Industrial Bulk Solids Handling until 1997. Then he joined to the department of Mechanical Engineering at Ben-Gurion University of the Negev, ISRAEL, where he serves as the Head of Department. On 2004 he served as a Visiting Professor in the Canadian Hydraulics Centre, National Research Centre Canada.

Prof. Levy published about 115 scientific papers, 40 chapters in books and presents over 150 papers in scientific conferences. His area of main interest centers on ‘transport phenomena in multiphase media’, ‘pneumatic conveying’, 'drying', ‘mass momentum and heat transfer’, 'heat pumps', 'bubble pumps' and ‘Shock wave interaction with porous and granular materials.