Polymer – surface interactions strongly influence many important industrial and rheological flows. In particular, polymer melts and solutions slip against the surface; this has long been associated with sharkskin and spurt in extrusion, and recent experimental observations suggest that slip also plays a role in the formation of enhanced concentration fluctuations in entangled polymer solutions....

The flow of viscous incompressible fluid over a periodically corrugated surface is investigated numerically by solving the Navier–Stokes equation with the local slip and no-slip boundary conditions. We consider the effective slip length which is defined with respect to the level of the mean height of the surface roughness. With increasing corrugation amplitude the effective no-slip boundary pla...

eunsteady slip-flow of second grade non-newtonian electrically conducting fluid over an oscillating sheet has been considered and solved numerically. a second-order slip velocity model is used to predict the flow characteristic over the wall. with the assumption of infinite length in the x-direction, the velocity of the fluid can be assumed as a function of y and t, hence, with proper change va...

[1] This paper analyzes slip on a fluid-infiltrated dilatant fault for imposed (tectonic) strain rates much slower than the rate of fluid exchange between the gouge zone and the surroundings and for exchange of heat slower than of fluid, typical of interseismic or most laboratory loading conditions. The limiting solution, corresponding to the infinitely rapid drainage rate, developed in the com...

We consider the classical problem of the stick-slip dynamics observed when peeling a roller adhesive tape at a constant velocity. From fast imaging recordings, we extract the dependence of the stick and slip phase durations on the imposed peeling velocity and peeled ribbon length. Predictions of Maugis and Barquins [in Adhesion 12, edited by K. W. Allen, Elsevier ASP, London, 1988, pp. 205-222]...

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...

The effects of partial slip on stagnation-point flow and heat transfer due to a stretching vertical sheet is investigated. Using a similarity transformation, the governing partial differential equations are reduced into a system of nonlinear ordinary differential equations. The resulting equations are solved numerically using a shooting method. The effect of slip and buoyancy parameters on the ...

The paper investigates the effects of surface stiffness on the slip process aiming to obtain a better insight of the momentum transfer at nanoscale. The surface stiffness is modeled through the stiffness, κ, of spring potentials, which are employed to construct the thermal walls. It is shown that variations of stiffness, κ, influence the slip mechanism either toward slip or stick conditions. In...

We report on a new method to characterize nanohydrodynamic properties at the liquid-solid interface relying solely on the measurement of the thermal motion of confined colloids. This equilibrium measurement of surface properties--equivalent in spirit to the passive microrheology technique used for bulk properties--is able to achieve nanometric resolution on the slip length measurement. Explorin...

Protein crystallization screens frequently yield salt crystals as well as protein crystals. A simple method for determining whether a crystal is composed of salt or macromolecules is suggested. A drop containing one or more crystals is transferred to a glass cover slip and the cover slip is then passed through the flame of a Bunsen burner. Macromolecule crystals are destroyed by this treatment,...