Generation of a Disturbance Wave on a Liquid Film Flowing Down a Heated Inclined Plane.

Abstract

An investigation was made into the generation of a disturbance wave on a liquid film flowing down a heated inclined plane. Theoretical analysis based on the instability caused by both dynamic and kinematic waves shows that the Marangoni effect due to surface tension gradient contributes to reduce the critical flow rate of liquid at the occurrence of a disturbance wave. Theoretical result also suggests the existence of two boundaries of generation of a disturbance wave at a fixed inclined angle. The flow pattern of a liquid film flowing on a heated brass duct was examined. As a result, one of the boundary which corresponds to the existence of the disturbance wave is qualitatively consistent with the theoretical result; the lower boundary, however, could not be observed because the liquid film breakdown occurred before reaching the lower critical flow rate. The measured velocity of a disturbance wave and its wave hight are also discussed in comparison with those of an isothermal liquid film flow.