Particle-driven convection occurs when a layer of fluid containing dense particles is located above a layer of clear, particle-free fluid. This can drive a variation on the classical Rayleigh-Taylor instability, where the particles induce the density difference between the layers. Variants of this instability occur in a number of geophysical flows, such as the undersides of volcanic ash clouds or sediment-laden river outflows.
Dr Megan Davies Wykes and PhD student Gaël Kemp, from the Department of Engineering, presented the results of new laboratory experiments, in which a layer of fresh water laden with dense particles was located above a layer of clear water. Megan also presented some preliminary results that examine the case in which a small amount of salt is added to the lower layer water in order to increase its density. For this second case, the initial stratification is stable, but becomes unstable due to particle settling.