Modeling of non-spherical, elongated particles for industrial suspension flow simulation

Abstract

Euler-Lagrange (EL) simulations of particulate suspension flow are an important tool to understand and predict multiphase flow in nature and industrial applications. Unfortunately, solid-liquid suspensions are often of (mathematically) stiff nature, i.e., the relaxation time of suspended particles may be small compared to relevant flow time scales. Involved particles are typically in the size range from μm to mm, and of non-spherical shape, e.g., elongated particles such as needle-shaped crystals and/or natural and man-made fibres. Depending on their aspect ratio and bending stiffness, those particles can be treated as rigid, or flexible. In this paper we present a recent implementation into the open-source LIGGGHTS® and CFDEM® software package for the simulation of systems involving stiff non-spherical, elongated particles. A newly implemented splitting technique of the coupling forces and torques, following the ideas of Fan and Ahmadi (J. Aerosol Sci. 26, 1995), allows significantly larger coupling intervals, leading to a substantial reduction in the computational cost. Hence, large-scale industrial systems can be simulated in an acceptable amount of time. We first present our modeling approach, followed by the verification of our code based on benchmark problems. Second, we present results of one-way coupled CFD-DEM simulations. Our simulations reveal segregation of fibres in dependence on their length due to fibre-fluid interaction in torus flow.