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ENCIT 2016
16th Brazilian Congress of Thermal Sciences and Engineering
IMAGING PROCESSING APPLIED TO GRAVITY-DRIVEN GRANULAR FLOWS THROUGH A VERTICAL PIPE
Submission Author:
Erick de Moraes Franklin , SP , Brazil
Co-Authors:
Carlos Azael Alvarez
Presenter: Erick de Moraes Franklin
doi://10.26678/ABCM.ENCIT2016.CIT2016-0218
Abstract
Gravity-driven flows of granular particles through a vertical pipe was studied experimentally using spatiotemporal diagrams obtained by digital imaging processing. The image processing was accomplished by employing a numerical code developed in MatLab in the course of this work. When the ratio of the tube diameter D to the grain diameter d is within certain limits, 6 ≤ D/d ≤ 30, granular flows may give rise to density waves. These waves consist of regions of high and low grain concentration, denominated granular plugs and air bubbles, respectively. Our experiments were focused in the high concentration regions. The granular flow was filmed by a high-speed camera, while the particles fell down through a transparent glass pipe. An oscillating wave regime was observed which depended on the mass flow rate and the degree of humidity. In this paper, we report measurements of the celerity and mean length of granular plugs. The plugs propagated downward, in the same direction as the granular flow, with constant celerity along the tube, and its size was independent of the mass flow rate.
Keywords
fine grains, density waves, image processing, granular flow
