Shock wave propagation in vibrofluidized granular materials
  Shock wave formation and propagation in two-dimensional granular materials under vertical vibration are studied by digital high speed photography. The steepen density and temperature wave fronts form near the plate as granular layer collides with vibrating plate and propagate upward through the layer. The temperature front is always in the transition region between the upward and downward granular flows. The effects of driving parameters and particle number on the shock are also explored. 
Kai Huang, Guoqing Miao, Peng Zhang, Yi Yun and Rongjue Wei