Net Unidirectional Fluid Transport in Locally Heated Nanochannel by Thermo-osmosis.

Thermo-osmosis driven by temperature gradients generally requires two liquid reservoirs at different temperatures connected by porous bodies or capillaries. We demonstrate, by molecular dynamics simulation, a new phenomenon toward nanoscale thermo-osmosis. Upon heating at a certain region of a nanochannel, multiple nanoscale convective layers are formed and can be manipulated to generate a net fluid transport from one reservoir to another, even without a temperature difference between them. A net unidirectional fluid transport with different rates can be achieved by precisely controlling location of the heated region. The net fluid transport can be enhanced further by tuning liquid-wall interactions. The demonstrated phenomenon provides a strategy for enhancing fluid mixing, which is often inefficient in nanoscale flows. Our finding is promising for chip-level cooling. The heat generated by chips can be employed to produce asymmetric temperature gradients in channels through proper configuration. Coolant liquids can thus be circulated without extra pumps.