Adaptive Mesh Refinement of the Solidification Front in Continuous Caster Simulations

A better understanding of the complex phenomena that occur along the solidification front in a continuous casting process is a fundamental necessity for reliably evaluating whether specific casting conditions inherently influence defect generation rates. Due to the intrinsic nature of the casting process, engineers are restricted in their ability to obtain accurate measurements of the shell development during casting operations. Through the end of the 20th century and up to the present, significant progress has been made in overcoming these limitations through the development of numerical models capable of accurately replicating the behavior of targeted phenomena that occur during the casting process. Continual revisions to these models have produced notable results; however, these approaches have primarily implemented predefined mesh representations of a system for simulation. The mesh utilized in any numerical simulation directly influences the results the model can generate. Developing an appropriate mesh capable of replicating the complex behavior of a system can require significant consideration of various factors involved in the construction of the mesh, the physics of the process being modeled, along with the solvers utilized in evaluating the system. Inadequate mesh construction may yield insufficient refinement for capturing desired aspects of a system or generating large areas of unneeded refinement. This article discusses characteristic behaviors and limitations of a select grouping of meshing algorithms currently available, as well as potential methods for avoiding mesh-driven solutions when simulating the solidification process in a continuous caster. Particular emphasis is placed on incorporating adaptive mesh refinement to lessen the potential for mesh-driven solutions and to reduce unnecessarily high cell-counts of the mesh through the restructuring of the mesh in accordance with the active simulation results. A numerical model was developed using the Simcenter™ STAR-CCM+™ software, and using Eulerian multiphase VOF melting and solidification models for steady-state simulations. Casting conditions and measurement data (provided by an industrial collaborator) were employed in defining boundary conditions, as well as for the model validation. The predicted shell profiles demonstrated good agreement with shell-thickness measurements obtained from the quarter-mold location of a recovered break-out shell segment.