Dynamic forces between a 50 microm radius bubble driven towards and from a mica plate using an atomic force microscope in electrolyte and in surfactant exhibit different hydrodynamic boundary conditions at the bubble surface. In added surfactant, the forces are consistent with the no-slip boundary condition at the mica and bubble surfaces. With no surfactant, a new boundary condition that accou...

We study the linearized stability of shear flow satisfying Navier slip boundary conditions. The Orr-Sommerfeld equation for the plane Poiseuille flow with Navier slip boundary conditions is solved numerically by the Chebyshev collocation method. Our numerical results show that slip at the boundary increases the critical Reynolds number Rc for instability. The dependence of the this critical Rey...

A systematic study into the effect of solid roughness on the slip boundary condition during shear flow is presented. Atomic roughness is modeled by varying the size and spacing between solid atoms at constant packing fraction while the interaction parameters and the thermodynamic state of the fluid are kept constant. It is shown that the fluid structure as manifest in the amplitude of the densi...

We present an experimental measurement of the slip length of air flow close to solid surfaces using an atomic force microscope (AFM) in dynamic mode. The air was confined between a glass surface and a spherical glass particle glued to an AFM cantilever. The Knudsen number was varied continuously over three decades by varying the distance between the two surfaces. Our results show that the effec...

We present an experimental study of a low-Reynolds number shear flow between two surfaces, one of which has a regular grooved texture augmented with a superhydrophobic coating. The combination reduces the effective fluid-surface contact area, thereby appreciably decreasing the drag on the surface and effectively changing the macroscopic boundary condition on the surface from no slip to limited ...

A difficulty in the classical hydrodynamic analysis of moving contact-line problems, associated with the no-slip wall boundary condition resulting in an unbalanced divergence of the viscous stresses, is reexamined with a smoothed, finite-width interface model. The analysis in the sharp-interface limit shows that the singularity of the viscous stress can be balanced by another singularity of the...

We describe experiments on stick-slip failure of a granular material within a linear shear cell. The experiments are performed in a quasi-two-dimensional photoelastic granular material which is sheared via a slider block and spring moving at a constant velocity. The apparatus can provide either constant-volume or constant dP/dV boundary conditions on the aggregate, and we observe boundary-condi...

Using the phenol-terminated polycarbonate blend as an example, we demonstrate that the hydrodynamic boundary conditions for a flow of an adsorbing polymer melt are extremely sensitive to the structure of the epitaxial layer. Under shear, the adsorbed parts (chain ends) of the polymer melt move along the equipotential lines of the surface potential whereas the adsorbed additives serve as the sur...

We investigate theoretically the influence of hydrodynamic slip at the surface of a nanofluidic channel on the efficiency with which electrokinetic phenomena can be used to convert hydrostatic energy to electrical power. Slip is introduced by applying the Navier boundary condition to the pressure-driven and the electro-osmotic components of the fluid velocity. A strong enhancement in the effici...

A thin-shell program for modeling neotectonics of regional or global lithosphere with faults. Influence of fore-arc structure on the extent of great subduction zone earthquakes. 1994: Effects of multiple phase transitions in a three-dimensional spherical model of convection in Earth's mantle. 2000: Role of temperaturedependent viscosity and surface plates in spherical shell models of mantle con...