Coupled DEM-SPH simulations of wet continuous screening

A Review of SPH Techniques for Hydrodynamic Simulations of Ocean Energy Devices

This article is dedicated to providing a detailed review concerning the SPH-based hydrodynamic simulations for ocean energy devices (OEDs). Attention is particularly focused on three topics that are tightly related to the concerning field, covering (1) SPH-based numerical fluid tanks, (2) multi-physics SPH techniques towards simulating OEDs, and finally (3) computational efficiency and capacity. In addition, the striking challenges of the SPH method with respect to simulating OEDs are elaborated, and the future prospects of the SPH method for the concerning topics are also provided.

Solid waste shape description and generation based on spherical harmonics and probability density function

Transport and separation processes of solid waste can only be modelled successfully with discrete element methods in case the shape of the particles can be described accurately. The existing techniques for morphological data acquisition, such as computed tomography, laser scanning technique, optical interferometer, stereo photography and structured light technique, are laborious and require a large amount of realistic solid waste samples. Therefore, there is a pressing need for an alternative method to describe the shape of solid waste particles and to generate multiple variations of particles with almost similar shapes. In this paper, a new method to describe solid waste particles is proposed that is frequency-based and uses spherical harmonics (SHs). Additionally, a new shape generation method is introduced that uses the shape description of a single particle to generate an array of related shapes based on a probability density function with a dimensionless control factor η. The newly proposed methods were successfully applied to describe the complex shapes of pieces of metal and plastic scrap. The shapes of these pieces of scrap can be described adequately with 15° of SH expansion and the overall divergence is within 0.1 mm. Five different values for η were tested, which generated shapes with the same distribution as the original particle. Rising levels of η cause the morphological variation of the generated particles to increase. These new methods improve the modelling of transportation and separation processes.

Modelling of large-particle-motion–heat-transfer coupling characteristics in rotary kiln based on discrete element method

A three-dimensional numerical simulation of the motion – heat-transfer coupling characteristics of waste tyre particles in a rotary kiln at 773–973 K was performed in this study. The particle dynamics and heat transfer characteristics were solved on a Lagrange grid. The motion model considered particle collisions using a nonslip collision model. Based on the particle motion results obtained, we considered three heat transfer mechanisms: particle–particle collision heat conduction, wall–particle radiation heat transfer, and wall–particle collision heat conduction. Subsequently, we established a mathematical model wherein the heat transfer associated with a particle is determined by its position in each time step, and implemented it on a JAVA platform to perform calculations. Finally, we obtained the temperature of each particle at each moment in the entire process. Further analysis of the simulation results shows that the average temperature and temperature standard deviation is governed by the wall temperature, rotation speed, and particle size.