Dependence of nanoconfined liquid behavior on boundary and bulk factors.

Nanoconfined liquid behavior is highly dependent on boundary and bulk factors. In this paper, we use a hybrid simulation method to investigate the variations of the velocity profile, temperature profile, slip length, and Kapitza length in nano-Poiseuille flows. They are determined by liquid behavior under the combined effect of boundary factors of solid-liquid bonding strength and surface roughness and bulk factors of the pressure gradient, maximum liquid velocity, flow rate, and dissipation heat. On the one hand, diverse variations of the profiles depend on the bulk factors. On the other hand, the boundary conditions of velocity slip and temperature jump, both strongly correlated to boundary factors, can significantly modify the velocity and temperature profiles. Based on this understanding, we find an explicitly local minimum value of the average temperature difference between liquid and solid when varying boundary and bulk factors lead to opposite influences. Moreover, we find that the Kapitza length varies as a power function of slip length and the index number depends on surface roughness but not on flow constraint. The results imply that by appropriately modifying the boundary and bulk factors, the confined liquid behavior is largely controllable.