Vortices are essential dynamic characteristics of fluid flow and play a dominant role in energy transfer, material mixing and flow regulation. When fluids are confined to the nanoscale, the generation and regulation of vortices exhibit distinctly different behaviors compared with macroscopic fluid flows.
In this work, all-atom molecular dynamics simulations are adopted to systematically investigate the water transport in two-dimensional valveless nanopumps driven by mechanical vibration, with a focus on the regulation mechanism of vortices on water transport efficiency. The simulation results show that introducing appropriately sized flow-disturbing structures into the nanochannels reduces the effective transport cross-sectional area, yet leads to an unexpected improvement in the water transport efficiency of valveless nanopumps. The water flow is approximately 4-10 times higher than that in smooth nanochannels without flow-disturbing structures. Combined with microscopic characteristics including velocity field, mean absolute vorticity, average kinetic energy distribution and number density distribution of water molecules, the inherent correlation between the evolution of vortex structures and fluid transport efficiency is elucidated.
This study not only enriches the fundamental theories of nanoscale vortex regulation and fluid transport, but also provides important theoretical basis and technical reference for the design, fabrication and performance optimization of high-performance two-dimensional nanofluidic devices.