Drag induced lift in granular media

TL;DR

This study investigates how the shape of an object dragged through granular media affects the lift force it experiences, combining experiments and simulations to understand the underlying mechanics.

Contribution

It introduces a method to approximate intruder lift forces in granular media by summing contributions from flat-plate elements based on local surface stress.

Findings

Lift force depends on intruder shape and orientation.

Lift forces can be predicted from flat-plate stress analysis.

Experimental and simulation results are consistent.

Abstract

Laboratory experiments and numerical simulation reveal that a submerged intruder dragged horizontally at constant velocity within a granular medium experiences a lift force whose sign and magnitude depend on the intruder shape. Comparing the stress on a flat plate at varied inclination angle with the local surface stress on the intruders at regions with the same orientation demonstrates that intruder lift forces are well approximated as the sum of contributions from flat-plate elements. The plate stress is deduced from the force balance on the flowing media near the plate.