Flow Regimes and Parametric Competitions in Nanochannel Flows

Nanoscale fluid flow systems involve both micro- and macroscopic parameters, which compete with each another and lead to different flow regimes. In this work, we investigate the competitions of four fundamental parameters, including the fluid-fluid, fluid-wall binding energies, temperature of the system, and driving force. By illustrating the fluid flux as a function of a dimensionless number, which represents the effective surface effect on the fluid, we show that the fluid motion in nanochannels falls into different regimes. For small fluid-fluid self-binding energy, there are three flow regimes; as the dimensionless number increases, the flux undergoes a transition from fluid-wall binding energy independent to temperature independent. If the fluid-wall binding energy is of the order of room temperature, there is a critical value for the dimensionless number, which divides the flow into weak and strong fluid-wall interaction regimes. Each of these regimes is associated with a distinct mechanism which reveals the competitions of the parameters.