Abstract
The aim of the present work is to investigate the existence regions of the different flow patterns exhibited by a liquid flowing down an inclined plane for a wide range of physical properties of the fluid (particularly surface tension and viscosity which were found to have the greatest influence). A model that predicts the decay frequency of oscillating or pendulum rivulets is presented. From this model, a stability criterion for the onset of oscillating rivulet flow is derived. Although the model does not contain any freely adjustable parameters, it shows good agreement with experimental measurements of rivulet decay frequency and of the transition point to pendulum rivulet. The transitions between different flow regimes are expected to cause drastic changes in heat and mass transfer rates between the liquid and the solid surface or between the liquid and the surrounding gaseous phase.