Experiments were performed in a sliding plate rheometer with a high density polyethylene to determine the conditions for the onset of slip and the relationship between slip velocity and shear stress. It was found that melt slip occurs at a critical shear stress of approximately 0.09 MPa in both steady and transient shear tests. The effect of the presence of a layer of fluorocarbon at the interf...

Numerical simulation of two-dimensional incompressible viscous ̄ows around an obstacle is considered. Two horizontal straight line arti®cial boundaries are introduced and the original ̄ow is approximated by a ̄ow in an in®nite channel with slip boundary condition on the wall. Then two vertical segment arti®cial boundaries are introduced and a series of approximate arti®cial boundary conditions ...

Industrial glass is produced at temperatures above 600 ◦C, where glass becomes a highly viscous incompressible fluid, usually considered as Newtonian. In the production two phases may be distinguished, namely the pressing phase and the blowing phase. This study will be concerned with glass flow in the pressing phase, which is called thus because a blob of fluid glass (called a gob) is pressed i...

We present a mesoscopic model of the fluid-wall interactions for flows in microchannel geometries. We define a suitable implementation of the boundary conditions for a discrete version of the Boltzmann equations describing a wall-bounded single phase fluid. We distinguish different slippage properties on the surface by introducing a slip function, defining the local degree of slip for mesoscopi...

Relying on the effect of microscopic asperities, one can mathematically justify that viscous fluids adhere completely on the boundary of an impermeable domain. The rugosity effect accounts asymptotically for the transformation of complete slip boundary conditions on a rough surface in total adherence boundary conditions, as the amplitude of the rugosities vanishes. The decreasing rate (average ...

[1] Natural faults have many characteristics in common with granular systems, including granular fault rocks, shear localization, and stick-slip dynamics. We present experimental results which provide insight into granular behavior in natural faults. The experiments allow us to directly image force chains within a deforming granular media through the use of photoelastic particles. The experimen...

In part I a well-known pair of cross phenomena, thermo-osmosis and mechano-caloric effect, in a dense gas is treated by a "thermo-hydrodynamical" method: the FOURIER and NAVIER-STOKES equations are adopted for heat conduction and viscous motion whereas in the boundary conditions MAXWELL'S thermal slip (3.1) and a mechanical surface heat flow (3.7) appear. Both of them are connected by an ONSAGE...

In this study the flow field of a nonlocal, diffusive upper convected Maxwell (UCM) fluid with a polymer in 3 a solvent undergoing shearing motion is investigated for pressure driven planar channel flow and the free boundary problem 4 of a liquid layer on a solid substrate. For large ratios of the zero shear polymer viscosity to the solvent viscosity, it is shown 5 that channel flows exhibit bo...

[1] We develop a spectral element method (SEM) for simulating dynamic rupture on rate and state faults and use it to study how the rupture is affected by a shallow fault region of steady state velocity-strengthening friction. Our comparison of the developed SEM and a spectral boundary integral method (BIM) for an antiplane (two-dimensional) test problem shows that for the finest resolution that...