Self-Sustained Flow in Janus Nanochannels Based on Thermo-Osmosis

Thermo-osmosis refers to the fluid flow that occurs in response to thermal gradients. Typically, thermo-osmosis is fluid flow from high to low temperatures. However, in certain cases, the direction of the thermo-osmosis may be from low to high temperatures, i.e., negative thermo-osmosis. By combining the positive and negative thermo-osmosis in Janus nanochannels, a self-sustained flow system is proposed in this work, wherein one side of the Janus nanochannel has a high surface energy and the other side has a relatively low surface energy. Molecular dynamics simulations show that the fluid within the Janus nanochannel can be driven by isotropic thermo-osmotic flow without any external pump. Additionally, the conditions required to generate self-sustained flow are presented, and the parameters affecting self-sustained flow are also discussed. In conclusion, the Janus nanochannel is believed to drive the fluid flow only using externally generated cold or heat without the need for an additional pump. Consequently, a deeper understanding of self-sustained flow at the nanoscale is critical for improving the theoretical framework of thermally driven mass flow and various emerging industrial applications such as efficient and energy-saving water purification and efficient energy conversion.