Experimental study of compound convection patterns in a layer of volatile fluid driven by a horizontal temperature gradient

Stability of, and pattern formation in, liquid layers driven by a horizontal temperature gradient have been studied extensively in various limiting cases. In thin liquid layers, thermocapillary stresses dominate and the instability typically leads to hydrothermal waves traveling in the direction of thermal gradient. In thicker layers, when buoyancy and thermocapillary effects are comparable (i.e., dynamic Bond numbers Bo_D=O(1)), a stationary pattern of co-rotating convection cells is found instead. However, the intermediate range, i.e., the transition between these two states, is not as well-studied. Linear stability analysis predicts that the emerging convection pattern should have hydrothermal waves on the cold side and stationary convection cells on the hot side. We discuss experimental particle-image velocimetry (PIV) studies of the flow in a liquid layer at Bo_D = O(0.1) driven by a horizontal temperature gradient and confined in a 4.85 cm × 1 cm × 1 cm test cell designed to test these predictions.