Evolution of temperature fluctuations in a heated film of liquid

Dynamics of temperature fluctuations on the surface of a vertically falling heated film of water are analyzed at Reynolds number 500 under conditions of motion of developed three-dimensional waves. It is shown that the high-frequency component of temperature fluctuations decays as long as the film moves in the heater bottom part. Some temperature perturbations are carried away into the rivulet region due to transverse thermocapillary forces. At high densities of heat fluxes, only the maximum temperature fluctuations generated by the largest waves reach the heater bottom. In this case, the averaged integral energy of temperature fluctuations in the interrivulet region is reduced.