Stability of moving surfaces in fluid systems with heat and mass transport — I: Stability in the absence of surface tension effects

A mechanism by which transport processes can produce instability of moving surfaces in fluid systems in considered. Stability of a moving boundary at which fog forms or vaporizes is analyzed using techniques of existing work on stability of moving solid surfaces. It is found that the vaporization case is always stable. But instability is predicted when fog forms at a boundary moving toward an initially supersaturated region. Stability of moving reaction fronts and of moving boundaries in ionic systems is discussed.