Development of Artificial Perturbations in a Nonisothermal Liquid Film

The effect of artificial perturbations on the formation of structures in a water film flowing over a vertical plate with a heater has been experimentally investigated. Attention has been focused on the study of the propagation of nonstationary perturbations in time immediately after their creation on the surface of the liquid film. The fluorescence method has been used to measure the film thickness field. The temperature field on the film surface has been measured by a high-speed infrared scanner. It has been shown that the passage of the wave front after the action of a perturbation system with the "most dangerous" distance between the cylinders leads to a change in the distance between the rivulets. It has been found that the intensity of introduced perturbations (cylinder diameters) and the characteristics of waves flowing to the heater significantly affect the change in the distance between the rivulets. An increase in the amplitude of the waves at the front of propagating perturbation has been detected. The coalescence of the rivulets in the lower part of the heater has been observed. It has been shown that the passage of several wave fronts is necessary for the complete rearrangement of the flow even when the intensity of perturbations is high.