Scaling vertical drag forces in granular mediaG. Hill, S. Yeung and S. A. Koehler
Department of Physics, Emory University - Atlanta, GA 30322, USA
received 20 June 2005; accepted in final form 29 July 2005
published online 31 August 2005
The average drag forces on intruders slowly plunging into and withdrawing from shallow beds of monodisperse smooth glass beads and of sifted rough sand scale with the immersion depth and lateral dimensions of the intruder. The withdrawal forces are comparable for both types of media; however, the plunging forces for sand are substantially greater than for smooth glass beads. Furthermore, for glass beads, the rescaled plunging and withdrawal forces have two different power law dependences on the immersion depth, with exponents greater than unity.
81.05.Rm - Porous materials; granular materials.
05.20.Jj - Statistical mechanics of classical fluids.
83.10.Pp - Particle dynamics.
© EDP Sciences 2005