Nonlocal hydrodynamic model for gravity-driven transport in nanochannels

It has been established that Newton's law of viscosity fails for fluids under strong confinement as the strain-rate varies significantly over molecular length-scales. We thereby investigate if a nonlocal shear stress accounting for the strain-rate of an adjoining region by a convolution relation with a nonlocal viscosity kernel can be employed to predict the gravity-driven isothermal flow of a Weeks-Chandler-Andersen fluid in a nanochannel. We estimate, using the local average density model, the fluid's viscosity kernel from isotropic bulk systems of corresponding state points by the sinusoidal transverse force method. A continuum model is proposed to solve the nonlocal hydrodynamics whose solutions capture the key features and agree qualitatively with the results of non-equilibrium molecular dynamics simulations, with deviations observed mostly near the fluid-channel interface. Published under an exclusive license by AIP Publishing.

Automated summary

The study investigates the impact of nonlocal shear stress on gravity-driven isothermal flow in nanochannels under strong confinement. The local average density model is used and the fluid's viscosity kernel is estimated using the sinusoidal transverse force method. A continuum model is proposed to solve the nonlocal hydrodynamics problem and its solutions are qualitatively compared with the results of non-equilibrium molecular dynamics simulations.