Propagation of large-scale artificial perturbations over gas-sheared liquid films

High rates of heat and mass transfer in annular gas-liquid flow are mainly achieved due to presence of large-scale disturbance waves. Under low liquid flow rates, the disturbance waves cannot be produced even for high gas speeds. Here we apply low-frequency oscillations of liquid flow rate to produce artificial non-uniformity of liquid film in absence of disturbance waves and investigate the evolution of these perturbations. The distance over which the perturbations survive grows with decreasing liquid flow rate and increasing gas speed. This method of flow control may be instrumental in improving the performance of industrial equipment working in the relevant range of flow rates.