| Particle multiphase flow problems involve many engineering related disciplines,such as energy,mining,metallurgy,petroleum,environmental protection,geotechnical and chemical engineering,etc.Although the behavior of single particles is easily analyzed,with the increase of the number of particles,the complex contact between particles leads to the behavior characteristics of the particles which are closely related to the scale of the multiphase flow system.For the chemical process involving particles,the characteristics of the particle multiphase flow system with different scales are completely different.It is necessary to test and analyze the size of the small scale and the scale of the pilot scale.The cost and time of the cold test and hot test of the small scale are still acceptable,but for the pilot scale,the cost of the test is too high and the test time is long.At present,in the field of engineering,it is urgent to establish a numerical model of engineering requirements with reasonable calculation cost,which can effectively replace the test times and shorten the time of research and development.In this study,a DEM-VOF model is extended to turbulent free-surface flows with particles,by means of Reynolds stress model(RSM).Besides,we adopt a novel virtual dual-grid porosity model to calculate the fluid porosity.The simulated results of single particle sedimentation,the falling of sinking particles and the floating of buoyant particles agree well to analytical and literatures,which validate the proposed DEM-VOF model.Furthermore,the DEM-VOF model developed in this paper is applied to the simulation of free surface flow with particles in solid-liquid mixing system for the first time.It is found that elliptical-head vessel is preferred to a flat-bottomed vessel for solid–liquid mixing by comparing the simulation results of four different stirred tanks,which agrees well to the related content of the book “Handbook of Industrial Mixing”. |
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