Spurious Grain Formation in Alloys Directionally Solidified on the Space Station Due to Marangoni Convection

Develop a three dimensional solidification model incorporating Marangoni convection and thermosolutal convection which can predict formation of spurious grains during DS. Extract data, such as, fluid velocities along stream lines as a function of distance from the surface-void, angular rotation of the fragmented side arms due to Marangoni flow lines, etc. from PFMI (Pore Formation and Mobility Investigation) videos, and then compare these observations with the simulations in order to quantitatively validate our numerical model. Use that model to predict formation of spurious grains in a totally different alloy, Al-7Si (MICAST), under varying processing conditions, such as, during re-melting prior to DS, after a step increase or decrease in growth speed vs at constant speed, etc.