5th International Conference on Advances in Solidification Processes (ICASP-5) 5th International Symposium on Cutting Edge of Computer Simulation of Solidification, Casting and Refining (CSSCR-5)

In this talk, we will review recent developments using the multiscale Dendritic Needle Network (DNN) approach for dendritic growth, with a particular emphasis on its application to convective transport in the liquid phase. The DNN method was developed for the modeling of dendritic growth of hierarchical needle-like dendritic crystals, which typically form at low solute supersaturation or undercooling that are common to a host of solidification processes. It retains a good accuracy for a numerical space discretization about one order of magnitude larger than what is typically required in phase field simulations. By not tracking complex morphological details of the solid-liquid interface, the DNN method allows a scaling-up of phase-field with quantitative simulations orders of magnitude faster, while still tracking the transient growth competition of individual dendritic branches in each grain at the larger scale of heat and mass transport. After briefly summarizing key aspects of the method, we will illustrate validations of the model in 2D and 3D, including quantitative predictions of microstructural features measured in directional solidification experiments, and critical quantitative comparisons with other multiscale approaches for dendritic growth. We will demonstrate the applicability of the model for fluid flow in the liquid phase. We will show that quantitative predictions comparable to those from phase-field simulations can be achieved, hence opening the way to macro-scale simulations with experimental/processing relevant transport conditions, e.g. accounting for gravity-driven buoyancy. We will offer a critical assessment of the DNN approach, of the investigations it makes possible, of its current limitations, and of the resulting next developments in order to address more complex mechanisms in dendritic growth. We will present ongoing work, challenges, and perspectives on the effect of buoyancy in constrained directional solidification, and on further coupling with micro-mechanical modeling, i.e. crystal plasticity, in order to link processing, microstructures, and properties.