ON THE INTERPRETATION OF PHASE MEASUREMENTS OF OSCILLATORY THERMOCAPILLARY CONVECTION IN LIQUID BRIDGES

In their study of time-dependent thermocapillary convection in cylindr ical liquid bridges Velten et al. [Phys. Fluids A 3, 267 (1991)] deter mined the azimuthal flow structure by measuring the phase of the tempe rature oscillations at three different azimuthal angles. Their explana tion of the data in terms of modes with wave number m = 0 is not alway s compatible with the normal-mode decomposition of the disturbances at the threshold. A new interpretation is given that explains the peculi ar phase measurements in terms of pairs of m not-equal 0 counterpropag ating waves.