Interaction of local instabilities during oscillatory convection

This experimental paper studies the time-dependent convective flows in Hele-Shaw slots which are heated from below. The evolution of oscillatory phenomena is traced through the time-dependent regime which is bounded on either side by regions of steady flow. The history of thermal events is recorded by thermocouples which protrude into the test fluid (silicone oil, $N_{\mathrm{Pr}=37\mathrm{}}$) at the four corners of the cavity. Flow patterns are visualized by holographic interferometry and temperature signals are analyzed using Fourier transforms and correlation functions. The results of this investigation suggest that the richness of the dynamic behavior of time-dependent convective flows in high-Prandtl-number fluids is determined by (i) the symmetry of the flow pattern and (ii) by the interaction of individual, spatially distributed instability events.