Is There a Critical Acceleration for the Onset of Convection?

摘要

Suppose granular material is shaken vertically with z(t) = A_0 cos(omega_0t). Can we expect to find convection if A_0omega~2 sub 0 < g? By means of theoretical analysis and computer simulation we find that there is no critical GAMMA = |A_0| omega~2 sub 0/g for the onset of convection. Instead we propose a modified criterion which coincides with GAMMA = 1 for small frequency omega_0.