蒸发、等温或冷凝薄液膜二维表面波的通用时空稳定性方程

UNIVERSAL FORMULATIONS OF TEMPORALAND SPATIAL STABILITIES OF TWO-DIMENSIONAL SURFACE WAVES ON EVAPORATING ISOTHERMAL OR CONDENSING LIQUID FILMS

处于蒸发或冷凝状态下的液膜,由于界面热不平衡效应的影响,导致其汽液界面条件与等温情形明显不同,这在一定程度上将影响液膜流动的稳定性。该文以边界层理论为基础,考虑完整的边界条件,推导沿倾斜壁面下降的、处于蒸发、等温和冷凝状态下普遍适用的二维表面波通用时空稳定性方程。方程中包含了雷诺数、热毛细力、倾角、流体物性以及蒸发、等温和冷凝条件的影响。通过中性稳定性特征曲线进一步分析了上述因素在不同雷诺数下的作用,从理论上揭示了液膜表面波流动的稳定性特征。

For evaporating or condensing films, the boundary conditions at vapour-liquid interface are different to those for the isothermal films due to the thermal non-equilibrium effect at interface, and the film stabilities are influenced to some extent. The universal temporal and spatial stabilities formulations of the two-dimensional surface waves on evaporating or isothermal or condensing liquid films draining down an inclined wall are established in present paper with the collocation method based on the boundary layer theory and complete boundary conditions. The models include the effects of Reynolds number, thermocapillarity, inclination angle, liquid property, evaporation, isothermal or condensation. The effects of listed above factors are investigated with the neutral stability curves at different Reynolds numbers, and stabilities characteristics are fully indicated in theory for evaporating or condensing films.