On the Rayleigh–Taylor instability for confined liquid films with injection through the bounding surfaces

An experimental and numerical investigation has been conducted to evaluate the hydrodynamic characteristics of a thin liquid film bounded by a downward-facing flat wall through which the liquid is continually injected. Both horizontal and inclined surfaces have been examined. The effect of different parameters, namely, the film thickness, liquid injection velocity, inclination angle and liquid properties on liquid film behavior have been examined. Non-intrusive optical techniques have been used to follow the transient evolution of the film free surface. Specifically, the frequency of droplet detachment, the size of the detached droplets, and the penetration depth prior to droplet detachment have been measured. These data have been compared against predictions of a mechanistic numerical model based on the level contour reconstruction front tracking method. The numerical model predictions are in good agreement with the experimental data.