Experimental investigation of convective motions under localized heating from below

Convective motions in a planar fluid layer heated locally from below via light absorption by a layer of opaque fluid on the bottom were investigated experimentally. Two additional effects are considered: the effect due to the existence of two spatial scales (the layer thickness and the diameter of the hot spot) and the effect due to light absorption. The observed convection regimes are classified, including self-oscillations. A diagram is presented depicting the dependence of the existence of different regimes on the modified Rayleigh number and the aspect ratio.