Influence of the thermocapillary structures interacting with waves on heat transfer in falling liquid film

The characteristics of the film flow were determined experimentally using simultaneous measurements of the thickness and temperature fields on the surface of a falling heated liquid film (laser-induced fluorescence and infrared scanner). Three different types of instability were registered on the surface of the heated liquid film: three-dimensional hydrodynamic instability and two types of thermocapillary instability. The development of thermocapillary structures was considered in the residual layer behind the front of the wave. These structures caused a disturbance in the following wavefront, leading to an increase in the amplitude of the waves. It was found that the amplitude of the hydrodynamic waves in the upper part of the heater could be increased. The development of thermocapillary structures at high heat fluxes initiated an increase in the rivulet deflection amplitudes. Heat transfer enhancement was registered with increasing amplitudes of wave and rivulet deflection.