Dense granular flow around a penetrating object: Experiments and hydrodynamic model

TL;DR

This study combines experiments and a hydrodynamic model to analyze the flow and drag force on a cylinder penetrating dense granular material, revealing flow localization and force scalings independent of velocity.

Contribution

It introduces a hydrodynamic model based on extended kinetic theory that accurately reproduces flow localization and drag force behavior in dense granular flow around a penetrating object.

Findings

Flow localizes near the cylinder

Drag force scales linearly with pressure and cylinder diameter

Flow regime is valid at low granular Reynolds number

Abstract

We present in this Letter experimental results on the bidimensional flow field around a cylinder penetrating into dense granular matter together with drag force measurements. A hydrodynamic model based on extended kinetic theory for dense granular flow reproduces well the flow localization close to the cylinder and the corresponding scalings of the drag force, which is found to not depend on velocity, but linearly on the pressure and on the cylinder diameter and weakly on the grain size. Such a regime is found to be valid at a low enough "granular" Reynolds number.