A Stability Investigation of Two-Dimensional Surface Waves on Evaporating, Isothermal or Condensing Liquid Films: Part I — Thermal Non-Equilibrium Effects on Wave Velocity

When the liquid film is in the process of evaporation or condensation, the interfacial thermal non-equilibrium conditions are evidently different from that of isothermal film, and this difference will affect the flow stability and wave velocity of thin liquid films. The temporal stability equation of the two-dimensional traveling waves of evaporating or condensing liquid films falling down an inclined wall is established based on the Prandtl boundary layer theory and complete boundary conditions. The effects on wave velocity of evaporating, isothermal and condensing states, thermocapillarity, Reynolds number, fluid property and inclined angle are discussed, and are compared in different Reynolds numbers.