Abstract: Rigorous modeling of heat and mass transfer in multicomponent (solidification) fluid for realistic boundary conditions is typically unwieldy. Hence, the motivation for simplification
is great. In this presentation, based on the generally valid transport equations and the appropriate dimensionless groups of fluid properties,
we point out (a)physically justifiable applications of mass diffusional transfer models for solidified fluid, and (b)the diffusion-induced bulk
flow denoted as micro-convection, which flows around the solid-liquid interface inside the width δ_c of interfacial liquid zone of significant
concentration changes. Our laboratory practice for oxide crystal growth has given valuable evidence for these considerations. Since the emphasis
is on the express of concept, we limit the discussion mostly to two-dimensional models in a binary system.

Key words: mass diffusion equation, solidification, mass microconvection