Wavy wall influence on the hydrodynamic instability of a liquid film flowing along an inclined plane

The film dynamic of a thin liquid along an inclined and wavy wall was numerically depicted in a weighted-residual integral boundary layer equation. A qualitative and quantitative analysis was initially carried out and accurate comparisons were obtained from experimental data on film instability along a flat and inclined as well as a wavy wall. To pinpoint the effect of waviness on film instability, 20 wavy wall periods in the computational CFD domain were considered. Several waviness parameters were studied and shown to have taken on a major role in the film instability process. Finally, a wide range of main wall inclination angles was taken into account, and consequent numerical data permitted identification of a threshold angle value. For wall angles higher than the threshold angle, the film behaved as though no corrugations were present. For lower angles, the film was repeatedly altered during the acceleration and deceleration phases.