The role of inter-particle friction on rheology and texture of wet granular flows
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THE EUROPEAN PHYSICAL JOURNAL E
Regular Article
The role of inter-particle friction on rheology and texture of wet granular flows Thanh-Trung Vo1,2,a and Trung Nguyen-Thoi1,2 1
2
Division of Computational Mathematics and Engineering, Institute for Computational Science, Ton Duc Thang University, Ho Chi Minh City, Vietnam Faculty of Civil Engineering, Ton Duc Thang University, Ho Chi Minh City, Vietnam Received 16 May 2020 / Received in final form 15 September 2020 / Accepted 15 September 2020 Published online: 6 October 2020 c EDP Sciences / Societ` a Italiana di Fisica / Springer-Verlag GmbH Germany, part of Springer Nature, 2020 Abstract. In order to get insight into the rheology and texture of rough unsaturated granular flows, we study the effects of the inter-particle friction coefficient on the macroscopic attributes and the texture variables of steady-state shearing flow of wet granular materials by relying on three-dimensional (3D) particle dynamics simulations. The macroscopic attributes are characterized by the macroscopic friction coefficient, macroscopic cohesion, and the packing fraction. The microstructural variables are characterized by the fabric and force anisotropies, the coordination number, and the stress transmission ratio. We show that the macroscopic observables behave as a function of the inertial number as a dry case for different values of the inter-particle friction coefficient. In particular, the macroscopic friction coefficient increases and the packing fraction decreases rapidly for small values of the friction coefficient, then they almost reach plateaus for higher values of the friction coefficient. Interestingly, all the macroscopic observables nicely behave as a function of the small values of the friction coefficient. Similarly, we also observe these characteristics for the fabric and force anisotropies and the coordination number as well as the stress transmission ratio which reflects the intermediate relationship between the microstructure and the mechanical behavior of such flows.
1 Introduction Understanding the rheological properties and microstructure of wet granular flows is a challenging problem in natural events and industrial applications [1–10]. Granular flows occur due to the collective motion of particles in a system of controlled pressure or imposed volume [11,12]. Such flows can be characterized by the macroscopic attributes such as macroscopic friction coefficient, macroscopic cohesion, and packing fraction as well as the microstructural variables such as fabric and force anisotropies, coordination number, and the stress transmission ratio (as defined in sect. 4) [13,14]. The macroscopic friction coefficient is given by μ = τ /σn , where τ is the shear stress determined by classical Mohr-Coulomb criterion (τ = μd σn + c) and σn is the confining pressure applied on the top wall of the sample [14–16], here μd is the macroscopic friction coefficient of the cohesionless granular flow and c is the macroscopic cohesion of material. Basically, μ and packing fraction Φ as well as c could be described
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