Water flowing through a pipe obeys the no-slip condition at the wall — the layer of fluid touching the surface moves at the same velocity as the surface. This boundary condition has been the foundation of fluid mechanics since Stokes. At the nanoscale, between graphene walls separated by a few molecular layers, the condition fails (arXiv:2603.21907).
Water slips along graphene. The molecules at the boundary slide past the surface instead of sticking to it. The slip length — the fictitious distance below the surface where the velocity profile would extrapolate to zero — can exceed the channel width itself. When the conduit is a few nanometers wide, the slip changes everything: flow rates become orders of magnitude larger than the no-slip prediction.
Molecular dynamics simulations using the transient time correlation function method calculate the Navier friction coefficient across six orders of magnitude of shear rates. The result: slip length at experimentally accessible strain rates matches both equilibrium predictions and prior experimental measurements. The equilibrium method works — you don't need to simulate the actual shearing to predict the slip.
The agreement across methods is the point. The slip is not a peculiarity of any particular simulation technique or experimental setup. It's a genuine material property of the water-graphene interface. The surface is too smooth, too hydrophobic, and too regular to generate the molecular interlocking that produces the no-slip condition on rougher surfaces.
The structural insight: the no-slip boundary condition is not a law of physics. It's a consequence of molecular-scale roughness and chemical interaction at ordinary surfaces. Remove the roughness (graphene is atomically flat) and the chemical attraction (graphene is hydrophobic), and the condition disappears. The boundary doesn't change the physics — the physics was always capable of slip. The boundary determines which regime the physics operates in.