A lattice Boltzmann study of the effect of stirring on the migration rate of a curved interface in binary slurries

Morphological evolution of particles in semisolid slurries has been modeled as the migration of a double-peak shape solid–liquid interface. The valley between the peaks represents the solute-trapping area between the dendrite arms. Various boundary shear conditions were considered to mimic the real processing environments. A lattice Boltzmann model for isothermal miscible binary flows has been utilized to handle the hydrodynamics and chemical diffusion. Fixed solute concentration at the solid–liquid interface was introduced to simulate the steady growth of the solid particle. Numerical simulations reveal that shearing the slurries in a direction perpendicular to the growth direction of the particle tips encourages dendrite growth, which agrees with the theoretical prediction based on interface stability analysis. Shearing the boundary along a direction parallel to the growth direction of the particle tips, however, caused a larger increment in the migration rate of the interface in the valley, and is considered the major reason for dendrite–rosette morphological transformation.