Inscrição na biblioteca: Guest

ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Free Surface Deformation in Oscillatory Thermocapillary Convection in a Rectangular Cavity

Get access (open in a dialog) DOI: 10.1615/IHTC12.80
6 pages

Resumo

The free surface displacement, liquid temperature fluctuations and flow field at the onset of oscillatory convection have been experimentally investigated in horizontal silicone oil (0.65cSt) layers in a rectangular cavity (15 mm long and 50 mm wide) with liquid heights ranging from 0.5 up to 4 mm and with a horizontal temperature gradient applied between the hot and cold walls.
When the applied temperature gradient reached a critical value, free surface oscillations were detected using a laser nanosensor simultaneously with temperature oscillations detected with a microthermocouple. For thick liquid layers, power spectrum data for both free surface and temperature oscillations revealed identical frequencies, which clearly indicates that the two are closely interrelated. At the same time the flow structures, identified using Particle Image Velocimetry technique, exhibited periodic streamwise changes with the same frequency as the recorded temperature fluctuations. This seems to correspond to a convective type of instability in which the surface deflections are coupled with the underlying bulk shear flow, as predicted by Smith and Davis (1983b). Additionally, the phase relation between the gas-liquid interface displacement and temperature has been investigated at different axial locations between the hot and cold walls.
For thin liquid layers, power spectrum data indicated that the temperature field oscillates independently of the free surface, suggesting that the mechanism for the onset of oscillations for thin layers is different from that responsible for thick liquid layers.