Infinitely thin evaporation front

Evaporative two-phase flow in a heated micro-channel resembles a two-phase slug flow with distinct domains of liquid and vapor. These domains are divided by the infinitely thin evaporating front, which propagates relatively to the fluid with a velocity u f equal (numerically) to the linear rate of liquid evaporation. In the frame of reference associated with micro-channel walls, the velocity of the evaporation front is... 

Taking into account the above-mentioned factors it is possible to present the stationary flow in a heated capillary as a flow of liquid and its vapor divided by an infinitely thin evaporation front. The parameters of these flows are related to each other by the condition of mass, momentum and energy conservation at the evaporation front. 

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