Density-driven convection roll in annular vibrated granular bed

Department of Mechanical Engineering, Muhammad Ali Jinnah University, Islamabad, Pakistan

^a e-mail: ndahmed@gmail.com

Received: 28 March 2012
Revised: 10 May 2012
Accepted: 28 June 2012
Published online: 3 August 2012

Abstract

The author presents the results of inelastic granular flow in an annular vibro-fluidized granular bed using hydrodynamic model suitable for dense inelastic granular gas. Using the steady-state balances of mass, momentum and energy for dissipative dense gas, the physics of the vibrated bed is initially validated in comparison with molecular dynamics (MD) simulations using the observable system parameters such as packing fraction and granular temperature. The instability of the vibrated bed is also explored due to the influence of additional dissipative inner wall. The phase map of inner and outer wall dissipations shows a characteristic line of division between the single roll systems with opposite rotations. In addition to single roll, a two roll system is observed as the density of the flow increases. The results show a qualitatively similar trend as seen in MD simulations for higher cell loadings. The findings are important as the results indicate that the increase in the packing fraction, in addition to side wall dissipation, leads to complex flow instabilities in the granular flow.