The evaporation wave, or "free surface boiling", is a type of violent vaporization that occurs in absence of nucleation. I understand that the thermodynamic limit for the onset of evaporation wave could be the spinodal curve. However, the spinonal curve is also the limit of homogeneous nucleation. Thus, in the metastable region, what are the key factors that determine whether the system undergoes homogeneous nucleation or evaporation wave?
I'm no much expert on that, but i'll cite some factors.
Both evaporation wave and nucleated bubbling are the same transition from thermodynamic point of view, what change is the dynamics.
1) nucleation energy: if there is high energy barrier against nucleation of bubbles, nucleation is inhibited and you get evaporation wave. Impurities and walls-> low energy barrier.
High liquid surface tension inhibits both processes, but I'll say that favour the wave (uncertain ;)
2) How much you are away from equilibrium: very far away, get nucleation. Quite near equilibrium, surface evaporation.
3) Timescale: the evaporation wave is a slow process (slower than speed of sound) while nucleation can come from a passing shock wave.
4) difference in volume between the two phases: high difference, it helps to get the evaporation wave dynamic, while works against nucleation thanks to surface tension
5) Dynamics of the discharge: the evaporation wave need a violent discharge to keep all mixing up. A slow decrease in pressure should not provoke it, the liquid will slowly evaporate (no wave) or nucleate bubbles.
6) An high viscosity of liquid or gas inhibit evaporation wave.
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