Pattern Formation And Convection Motion Of Horizontally Vibrated Granular Materials

Convection,segregation and pattern formation in horizontally vibrated granular systems are complex phenomena.These phenomena are important for the improvement of several industrial developments such as agriculture,mining,pharmaceutical,geo-sciences,and civil engineering,etc.The most of the previous theoretical and experimental works were focused on vertical vibration direction;only limited studies explored the horizontally vibrated granular systems.In this thesis,we studied horizontally vibrated monolayer of mono-sized granular particles systems,a monolayer of binary granular particles system,a deep layer of binary granular particles system and relations between these systems.At first,a monolayer of 500 g active aluminum oxide particles of size d = 8.0± 0.2 mm was filled in a squire container of size(LX=25 cm,LY=25 cm,LZ=18 cm)and vibrated horizontally with frequencies f = 5 Hz,10 Hz,and 15 Hz,respectively,dimensionless acceleration ?varied from 0.8 to 1.4.Four different regions namely Solid Region,Cluster Region,Gassy Region and Empty Region,as well as a 3D state(when particles jumped from one of the corners of the container),were observed in the system,Moment of inertia I of the particles played a significant role in energy dissipation and convection motion.This work also related the moment of inertia with angular momentum L and linear velocity vt of the system as I?(Lv,).Convection motion can be observed when the product of angular momentum and linear velocity(Lv,)>2.24X104 gcm3/s2 and dimensionless acceleration ??1.2.Vibrating frequency f does not affect 3D state;this state depends only on the dimensionless acceleration ?.Moreover,we also studied a horizontally vibrated monolayer of 400 g active aluminum oxide particles at frequencies of 5 Hz,10 Hz,and 15 Hz,respectively,where dimensionless acceleration ? varied from 0.8-1.4.Different modes of convection,such as non-convection,two rolls convection,one roll clockwise convection,and one roll counter-clockwise convection modes,were observed in the system.Different densities regions were also observed in the system as Gassy,Empty,Cluster and Solid Regions.Empty Region size affects the densities of all regions and no prominent effect of Cluster Region was observed on convection modes.When kinetic energy ratio of Gassy and Solid regions(?= kg/ks)were about 0.02,5.36,6.85 and 8.76,Non Convection mode,Two Rolls Convection mode,One Roll Clockwise Convection mode,and One Roll Counter-Clockwise Convection modes were observed in the system,respectively.We also investigated a monolayer of binary size particles system vibrated with fixed frequencies ranging from 2 Hz-7 Hz and dimensionless acceleration ?varied from 0.10-1.7.Different phases were observed in the system.At first,clusters evolve and extend to stripe formation,then clear stripe patterns begin to form,at that point,convection motion was started in the system beginning with one Counter-Clockwise Convection Roll and then One Clockwise Convection Roll.Afterwards,the numbers of convection rolls were increased and stripe distribution changed to homogeneous distribution.This transition of phases,final patterns and types of convection motion depended on the dimensionless acceleration,the energy supplied to the system and the average velocity of particles.In chapter 7,we investigated a deep layer of binary mixture d=(4.0 ± 0.2)mm and d=(8.0 ±0.2)mm particles.The system was vibrated horizontally with frequencies of 5 Hz,10 Hz,and 15 Hz respectively,where dimensionless acceleration ? varied from 0.8-1.4.We observed different types of movement of particles in the system.Helical movement of large particles was observed along the walls perpendicular to direction of vibration and straight-line movement was observed on walls parallel to direction of vibration.Movement direction of large particles along the walls parallel to direction of vibration affected the convection rolls.When large particles along the walls parallel to direction of vibration moved in opposite direction homogeneous convection rolls were observed in the system and when moved in the same direction,convection rolls were observed in the corners of the container.Helical and straight-line movements of particles along the walls were the part of convection motion.A heap was appeared due to vibration,which had a dominant effect on the convection rolls.Heap position was the function of frequency f and dimensionless accelerations ?.