Modelling the dissolution of compound particles

Abstract

In this thesis, a study of modelling the dissolution of compound particles for two different phases (A and B) was performed using Smoothed Particle Hydrodynamics (SPH) with LAMMPS and blueBEAR. The results were visualized with OVITO and postprocessed with MATLAB. The goal of the study was to see the effect of varying Schmidt numbers and different Reynolds numbers on dissolution rate. In the simulations, phase A was found to diffuse more slowly compared to phase B. In most runs, phase B dissolved faster. When the composition was mostly comprised of phase A, a barrier effect was observed, where phase A remained at the surface and hindered the dissolution of phase B. The main effect from varying the Reynolds numbers from 1, 10, and 100 was the transition from diffusion-controlled to convection-limited regimes. At Reynolds number 1, the dissolution rate was slow, and it was controlled by diffusion. Reynolds number 10 dissolution was faster compared to 10 but slower than 100. At Reynolds 100, the effect of strong convection is seen clearly, and most particle phases dissolve within 5-15 seconds as opposed to 20 plus seconds for Reynolds 10 and 1 cases. All in all, SPH was a handy tool in modeling the dissolution of compound particles and providing important dissolution rate information that may be useful to formulators intending to create chemical engineering products or pharmaceutical companies seeking a specific dissolution rate for their drugs.