Interaction of a granular stream with an obstacle

TL;DR

This study numerically examines how a granular stream interacts with an obstacle, revealing different force behaviors at high and low velocities, including a gas-filled gap formation at low velocities.

Contribution

It provides new insights into the velocity-dependent forces and gap formation in granular streams impacting obstacles, highlighting a transition from quadratic to different force laws.

Findings

Force proportional to velocity squared at high speeds

Gap formation with granular gas at low speeds

Different force laws depending on stream velocity

Abstract

We investigate numerically the interaction of a stream of granular particles with a resting obstacle in two dimensions. For the case of high stream velocity we find that the force acting on the obstacle is proportional to the square of the stream velocity, the density and the obstacle size. This behavior is equivalent to that of non- interacting hard spheres. For low stream velocity there appears a gap in between the obstacle and the incoming stream particles which is filled with granular gas of high temperature and low density. As soon as the gap appears the force does not depend on the square of velocity of the stream but the dependency obeys another law.