Modelling segregation of bidisperse granular mixtures varying simultaneously in size and density for free surface flows

Abstract

Abstract

Drag force in granular shear flows: regimes, scaling laws and implications for segregation

“…This also leads to a terminal velocity-like formulation for the intruder velocity (4.2) by combining the Stokesian drag model with a previously established Archimedean segregation force model for uniform shear flows (Jing et al 2020). As discussed in § 4.2, this 'granular terminal velocity' captures the dependence of the intruder segregation velocity on the flow conditions and the particle size and density ratios, matching our simulation results of gravity-driven segregation of heavy intruders in uniform shear, as well as resembling some aspects of previous segregation studies using heap flow (Schlick et al 2015;Xiao et al 2016;Duan et al 2021), cyclic shear (Trewhela et al 2021) and bedload transport (Rousseau et al 2021). Hence, although our drag model is developed in an idealized uniform shear flow in the absence of gravity for an isolated intruder, it appears to be relevant to more complicated granular shear flows where stress gradients and kinematics gradients exist.…”

“…Note that w i is normalized by γ0 d, a constant characteristic velocity for each data series. Interestingly, the values of w i /( γ0 d) (varying from 0.01 to 0.3) for R 3 are quantitatively consistent with previous segregation velocity results for size-bidisperse and density-bidisperse mixtures in heap flows (Schlick et al 2015;Xiao et al 2016;Duan et al 2021), confirming the connection between w i determined from the force balance on a single intruder (4.2) and the segregation velocity model determined in particle mixtures to predict segregation in granular flows (Umbanhowar et al 2019).…”

“…2016; Duan et al. 2021), confirming the connection between determined from the force balance on a single intruder (4.2) and the segregation velocity model determined in particle mixtures to predict segregation in granular flows (Umbanhowar et al. 2019).…”

Viscous Effects on the Particle Size Segregation in Geophysical Mass Flows: Insights From Immersed Granular Shear Flow Simulations

“…Particle interactions are simulated using a Hertz contact model with Young's modulus Pa, Poisson's ratio , coefficient of restitution , and friction coefficient . These contact parameters are derived from recent literature of particle size segregation (Duan et al., 2021; Fan et al., 2014; Schlick et al., 2015) and from granular rheology studies (Silbert et al., 2001), and have been found to adequately replicate behaviors observed in real granular flows (Jing et al., 2020; Tripathi & Khakhar, 2011). In order to improve computational efficiency, Young's modulus used in this study is lower than that of real glass beads, but it has been previously verified that this reduction does not affect the results (Jing et al., 2018, 2020).…”

Mild stratification in drying films of colloidal mixtures

“…18,19 It is important to study a bidisperse colloidal system with two types of particles of different sizes to understand the drying characteristics of a multi-component system. Several studies have investigated bidisperse films 17,[20][21][22] and other applications [23][24][25][26][27] with small particle size ratios (mostly lower than 3). Bidisperse films may be stratified according to the size of the particles across the final film height, depending on the drying conditions.…”