Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
EXPERIMENTAL INVESTIGATION SIZE PARTICLES SEGREGATION BY LAMINAR SHEARING FLOWS
Submission Author:
Jaime Gonzalez-Maya , SP
Co-Authors:
Jaime Gonzalez-Maya, Fernando David Cúñez, Erick de Moraes Franklin
Presenter: Jaime Gonzalez-Maya
doi://10.26678/ABCM.COBEM2021.COB2021-1970
Abstract
In this work, annular flume experiments are carried out to study a granular bed sheared by a viscous flow. The aim is to investigate the mechanism of segregation of coarse grains within a bi-dispersed granular bed sheared by a Couette flow. The annular flume mimics an infinitely-long river, enabling us to observe the evolution of the motion of the particles from the inception of the motion until the transport of the particles as bedload. In some cases, the bed material consists of a wide range of particles that has different grain sizes, densities, and shapes. Usually, those particles segregate by the presence of a viscous shear rate. From an engineering point of view, it is crucial to predict this phenomenon’s occurrence and nature. In our experiments, the granular bed consisted of two sizes of glass beads whose mean diameters are d s = 2.00 mm and d l = 3.17 mm, and the channel was filled with sodium iodide (NaI) solution at 35% (w/w) in glycerin. We imposed a mean fluid velocity ranging from 0.095 m/s to 0.36 m/s by rotating Ω the flume lid (5 to 20 RPM), which ensured the particles transport as bedload. Under these conditions, we filmed the bedload layer with a digital camera to record the real-time positions of single particles by acquiring the fluorescence intensity from a laser dye traversing the fluid (refractive index matched RIM technique). We automatically identified and tracked the particles along images by using numerical scripts, from which we computed parameters such as velocity profiles and particle trajectories. The mechanisms of segregation of coarse beads towards the granular surface over time were identified and are explained in this work.
Keywords
Bed-load layer, Sediment Transport, laminar flow, granular segregation, shearing
