Smoothed Particle Hydrodynamics studies of heap leaching hydrodynamics and thermal transport

摘要

This thesis is concerned with the development and application of Smoothed Particle Hydrodynamics (SPH) models for studying multiphase flows such as those relevant to the analysis of the hydrodynamics and thermal transport involved in heap leaching.udThe improvements made here to the modelling aspects of multiphase SPH are seen to bring about measurable improvements to solution quality. A relative density formulation and a “compressibility-matching” method for handling interfaces eliminate what would otherwise be significant obstacles to obtaining stable and smooth pressure fields.udThe convergence properties of the formulation are seen to approach the theoretically expected value in SPH. Convergence is also seen to strongly depend on the smoothing length factor used. A factor found to influence error magnitudes that nevertheless does not affect convergence rates is the extent of initial particle disorder.udThe simplified cases representative of heap leaching hydrodynamics studied through 2D simulations allow an understanding of flow at the particle scale. The significant dependence of mean flow rates in these systems on particle sizes, saturation and contact angle is shown.udIn 3D, saturated flows through packed beds of spherical particles are presented. Steady-state superficial velocities obtained through simulations, compared with analytical relationships given by Cozeny-Karman and Ergun relations are illustrative of the ability of SPH to reproduce packed bed flows satisfactorily.udSubsequently unsaturated regimes encountered at the channel scale are studied qualitatively for saturation values typical of real heaps.udA heat transfer model based on a formulation for single-phase SPH developed by Szewc et al. is implemented. The model’s performance (in terms of Rayleigh numbers indicative of transition to unsteady convection in differentially heated cavities (DHCs)) is satisfactory when compared with the established single-phase results of Le Quere. Its application to an idealised unsaturated scenario demonstrates its useability for multiphase studies.udFinally, an extension is made to the model to account for turbulent regime heat transport. This extension, deriving from one used for finite elements by Chatelain et al. is novel in the SPH context and lets the loss of stratification seen in DHCs at high Rayleigh numbers be predicted with reasonable accuracy.