Date | Time
12/01/2015 | 2 h 00 min - 6 h 00 min
Salle du Conseil – IJL – Saurupt
« Numerical modeling of dendritic solidification at a mesoscopic scale »
Collaborators: H. COMBEAU, M. ZALOZNIK, C. BECKERMANN, V.F. DE FELICE, A. VIARDIN
Dendritic (treelike) crystals or grains are the most common growth form in solidification of metal alloys.
Their growth is governed by an intricate interplay between diffusion or convection of heat and chemical species and capillary effects. Furthermore, in castings the growth of den-dritic crystals is influenced by adjacent grains. The grains can “feel” each other due to the over-lap of thermal and solutal fields surrounding each growing grain.
The mesoscopic solidification model – originally proposed by Steinbach, Beckermann and coworkers – overcomes the limitations of phase-field methods: it can be applied at larger scales and can include fluid flow at reasonable computing cost. It consists of the description of a dendritic grain by an envelope that links the active dendrite branches. The grain is modeled as an evolving porous medium and the liquid-solid phase change and convection-diffusion transport are modeled by volume-averaged equations. The velocities of the dendrite tips are determined by the local conditions (temperature, solute concentration) in the proximity of the envelope through an analytical stagnant-film model.