Development of a phase change solver for concentrated energy beam applications

Abstract

A phase-change computational fluid dynamics (CFD) solver module was developed for the numerical solution of melting, solidification and evaporation of any substrate under a concentrated energy beam (CEB). The solver module was developed as a part of general purpose CFD solver AnuPravaha. It is a finite volume method-based CFD solver capable of numerical solution of various fluid flow and heat transfer problems over the hybrid unstructured grid. The phase change module for CEB applications was developed in 2-D planer, 2-D axis-symmetric and 3-D framework. A fixed grid enthalpy-porosity technique was used to capture the phase change phenomena. CEB was implemented as a surface heat flux boundary conditions. Various associated phenomena like Marangoni flow and natural convection was studied for laminar flow regime.The solver for turbulent flow is currently getting developed. The numerical solver was validated for melting of copper and melting and evaporation of tin under a 270o bend pencil Electron Beam Gun (EBG) evaporator. The numerical solutions from the solver were found to be in very good agreement with experimental results with less than 5% deviation. A case study was carried out using the validated solver for maximizing the molten pool fraction in the evaporator system for laser based purification processes. It was observed that for the particular geometry of the evaporator, the e-beam power and crucible thickness variation did not assist significantly in maximizing the molten pool fraction. However, the variation in the aspect ratio improves the molten pool fraction significantly. Studies like these can be utilized for designing new evaporator cavity with optimized parameters.