Abstract
The generation of a disturbance wave on a free falling film along an inclined plane was analyzed theoretically based on a wave equation for small fluctuations of velocity, shearing stress and film thickness. The results show that a small wave grows to be a disturbance wave when the velocity of kinematic wave, C0, exceeds the velocity of dynamic wave, C+.
The critical flow rate at the occurrence of disturbance wave calculated by the theory agrees with the observed value. The critical flow rate decreases as the inclination angle increases, and also the kinematic viscosity and the surface tension of liquid decrease. The measured velocity of disturbance wave is much greater than the mean velocity of liquid film, and the wave height is much higher compared with the base film thickness. Therefore, a disturbance wave plays an important role in the liquid transportation.
