Mechanisms leading to the formation of double-diffusive layers during unidirectional solidification of aqueous NH4Cl solution

Double diffusive layers (DDLs) are one of the flow patterns which arise due to the coupled effects of thermal and solutal gradients and find relevance in large-scale applications. We report observations of DDLs using unidirectional solidification of a binary mixture, which naturally introduces thermal and solutal buoyant flows. The convection rolls at the opposite sidewalls, having an opposite sense of rotation, ultimately merge to form the DDLs that expand throughout the breadth of the test chamber. Our research on exploring the mechanisms of DDLs uses a combination of nonintrusive techniques capturing full-field measurements in real-time to obtain insights on their evolution.