Development of an open-source heat and mass transfer model for Floating Zone growth

The growth of crystals using the Floating Zone (FZ) method involves a complex interplay of heat and mass transfer phenomena, including electromagnetic heating, radiative heat transfer, melt convection, phase change, and complex shapes of phase boundaries. Numerical simulation is key to understanding these coupled phenomena and optimizing growth conditions. Open-source modeling tools provide a flexible foundation for simulating complex crystal growth processes. This work presents a general-purpose small-scale FZ model for the growth of small-diameter crystals, implemented entirely in the open-source software OpenFOAM. The transient, 2D axisymmetric model supports both inductive and optical heating configurations. The framework extends OpenFOAM with custom solvers, boundary conditions, and utilities for electromagnetic fields, heat transfer with internal sources, melt flow with external forces, phase change, and free surface tracking with growth angle enforcement. A simple stepwise coupling approach is followed to solve the multiphysical problem. The model is verified against analytical solutions and validated with literature data, demonstrating accurate prediction of temperature fields, flow patterns, and interface shapes. The new framework offers a flexible, extensible platform for future FZ crystal growth studies.