Thermofluidic effects in nanochannels

When a fluid is subject to a temperature gradient, a velocity field can be generated, a phenomenon known as convection. It should be noticed that, such phenomena parallel what happens to electrons in a metal: temperature gradient drives electrical current under the name of thermoelectric effect. Now as things can be made smaller and smaller, it becomes an interesting subject to investigate the so-called micro- or nano-fluidic flow: liquid flow through a micro-size or nano-size channel. In this study by researchers from Hong Kong [PRL 105, 174501 (2010)], they used molecular dynamics simulations to examine a nano fluid housed in a nano-channel with particularly designed walls: the wall consists of two parts, the left and the right one, with respective surface energies, and a temperature gradient is held symmetric with respect to the border between the left and right wall. Their study showed that, an asymmetric flow can be generated with this temperature gradient provided the variance of surface energies is big enough. This is funny and many possibilities can be imagined to broaden their studies.