Rising and sinking intruders in dense granular flows

Abstract

We computationally determine the net bed force on single spherical intruder particles in dense granular flows as a function of particle size, particle density, shear rate, overburden pressure, and gravity. A simple buoyancy-like scaling law is recovered (analogous to that in fluids), but with a scale factor that depends on the particle size ratio due to discrete contacts. Comparing the bed force with the intruder weight results in predictions of whether an intruder rises or sinks that agree with data from various independent experiments of free surface granular flows.