Heat transfer enhancement and interaction of rivulets on the surface of a heated liquid film

The flow of an aqueous film along a vertical heater was studied for Reynolds numbers of $33{,}~50$, and $105$ and initial temperatures $T_0 = 15{,}~23{,}~30$, and $40^{\circ}$С. It was shown that the amplitudes of the zigzag motion of the rivulets increased with increasing heat flux density. The most intensive growth of amplitudes was observed with the development of thermocapillary instability in the upper part of the heater. For high heat fluxes, when the amplitude of the zigzag motion reached a sufficiently large value, interaction of the rivulets began. Several types of interaction of rivulets on the surface of the heated liquid film were distinguished. It was shown that the appearance of a thermocapillary structure in the upper part of the heater led to movement of rivulets and an increase in the heat transfer intensity.