Continuous chute-flow rheometer: A multi-modal approach to dense granular flows--颗粒学报PARTICUOLOGY

Henry, K., Chen, Z., Wassgren, C., & Mort, P. (2025). Continuous chute-flow rheometer: A multi-modal approach to dense granular flows. Particuology, 101, 146-154. https://doi.org/10.1016/j.partic.2024.08.011

Continuous chute-flow rheometer: A multi-modal approach to dense granular flows

Kayli Henry^a, Zhengpu Chen^b, Carl Wassgren^c, Paul Mort^a *

a School of Materials Engineering, Purdue University, West Lafayette, IN, USA
b School of Agricultural and Biological Engineering, Purdue University, IN, USA
c School of Mechanical Engineering, Purdue University, West Lafayette, IN, USA

10.1016/j.partic.2024.08.011

Volume 101, June 2025, Pages 146-154

Received 10 May 2024, Revised 31 July 2024, Accepted 23 August 2024, Available online 5 September 2024, Version of Record 29 May 2025.

E-mail: pmort@purdue.edu

Highlights

• Continuous granular-flow rheometer with multi-modal sensing: flow rate, torque, particle velocimetry.

• Orthogonal shear fields affected axial flow rates.

• Specific torque was calculated relative to active mass in shear fields.

• Orthogonally-sheared draining experiments had linear ranges with steady flows and specific torques.

• The relationship of specific torque and outflow rate suggests a pump-curve analogy.

Abstract

This study describes a model-directed experimental approach toward the measurement of dense granular rheology. It used a concentric cylinder rheometer tilted along an axis, essentially a chute flow where applied shear can further affect the continuous dense flow of granular media. Experiments were done using draining flows over a range of shear rates imposed by the concentric rotor within the device. Multiple sensors were used to investigate the interaction of mass holdup, shear rate, specific torque, particle velocity, and discharge mass flow rate. A linear range was observed wherein the specific torque and mass flow rate remained steady during draining. The flow rate, specific torque, and particle speed measurements increased with increasing rotor speed. The relative variance of the mass flow rate was found to be proportional to the temporal scale of scrutiny; it decreased at higher shear rates for short time intervals. Wall slip at the rotor was inferred from particle velocity measurements. With increasing shear rate, gradual increases in flow rate were observed combined with increased specific torque and wall slip. A sharp transition between quasi-static and dense-inertial regimes was not observed with this device; instead, the observed increase in specific torque was gradual with an apparent asymptotic limit, suggesting a pump-curve analogy where the outlet mass flow rate was controlled as a function of orthogonal shear.

Graphical abstract

Keywords

Dense granular flow; Granular rheology; Couette; Chute; Continuous; Multi-modal sensing

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