Measurement of Velocity and Particle Size in Shock Wave Area Generated by Experimental Granular Flow Impacting on a Cylinder Based on Image Processing Methods

Abstract

AbstractThe measurement of flow velocity and particle size remains an important issue in granular -flow dynamics and can provide important basis to better understand the physics in granular material, particularly when it impacts on a structure. In this study, laboratory chute experiments were performed with quartz-glass particle materials to investigate the characteristics of granular shock developed upstream of a cylinder generated by granular flow impacts. A time series of flow images recorded by a camera has been analyzed and processed using the digital image processing methods such as the gray processing, the image binarization, the image corrosion and expansion, and the generative adversarial networks, with a goal of obtaining flow velocity and particle size in the granular shock area. The experimental results reveal that the granular-flow velocity grows with increasing slope angle. The granular shock thickness shows a general increase with the growing number of particles in the shock area, and the number of particles demonstrates an inversely proportional to increasing Froude number, providing a potential method for determining the particle size of dense granular flow. The findings of this study could help to better understand the shock dynamics of granular flow impacting on an obstacle.