Waves in granular flows down a vertical chute

¹ Department of Space, Planetary & Astronomical Sciences and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
² Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
³ Department of Aerospace Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India

^* e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
^** e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
^*** e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Published online: 1 December 2025

Abstract

The flow of granular materials in confined, gravity-driven chute systems is important to various industrial processes. Despite its long research history and practical relevance, solutions to chute flows and their stability continue to be investigated. This study examines the dynamics of granular particles in a vertical chute of a square cross section with nominal side of 50 mm under gravity, focusing on how variations in solid fraction and wall friction influence wave formation in the form of cross-stream oscillations. Using discrete element method simulations, we model the behavior of 2 mm spherical particles that interact through the Hertz- Mindlin contact model with periodic boundaries in the lateral (x) and flow (y) directions. The conditions in the walls in the remaining spanwise direction (z) are varied systematically, including various combinations of walls that are flat-rough and/or bumpy-smooth. Our study indicates that at increased solid fractions, the granular flow transitions to a wave-dominated regime, as the particles descend under gravity. The occurrence and characteristics of these waves are strongly influenced by wall conditions.