1987 Volume 13 Issue 5 Pages 649-656
Formation and structure of waves on the surface of falling liquid films in inclined wetted-wall columns were theoretically investigated on the basis of the linear stability theory. Approximate analytical solutions were obtained for the dimensionless numbers of length, velocity and spacial growth rate of temporally stable waves as a function of the liquid Reynolds number, the dimensionless surface tension, the inclination of the wetted-wall plate and the dimensionless wave frequency. The solutions showed that the wave is very small at the liquid inlet but that its amplitude increases exponentially in the direction of flow.
Frequencies, lengths, velocities and amplitudes of waves of water were measured in an inclined wetted-wall column. It was found that, with increasing distance in the direction of flow, the wave characteristics remain constant but the wave amplitude increases, and that visible waves appear at a point, i.e. a wave inception. A comparison between the experimental results and theoretical predictions indicated that the characteristics and inception of the waves can be predicted on the basis of the linear stability theory.
