Molecular dynamics simulations are carried out to investigate the dynamic behavior of the slip length in thin polymer films confined between atomically smooth thermal surfaces. For weak wall-fluid interactions, the shear rate dependence of the slip length acquires a distinct local minimum followed by a rapid growth at higher shear rates. With increasing fluid density, the position of the local ...

We present a quantitative analysis of the effect of rough hydrophobic surfaces on viscous newtonian flows. We use a model introduced by Ybert and coauthors in [17], in which the rough surface is replaced by a flat plane with alternating small areas of slip and no-slip. We investigate the averaged slip generated at the boundary, depending on the ratio between these areas. This problem reduces to...

This paper presents a model for predicting pressure losses in foams of various expansions and pressures, in pipes of any given diameter, once the foam behavior has been characterized at a single expansion and pressure. The model incorporates a modified form of the power-law viscosity model of foam, which is obtained through the method of volume equalization. Since apparent wall slip contributes...

Total internal reflection fluorescence (TIRF) microscopy can be used in a wide range of cell biological applications, and is particularly well suited to analysis of the localization and dynamics of molecules and events near the plasma membrane. The TIRF excitation field decreases exponentially with distance from the cover slip on which cells are grown. This means that fluorophores close to the ...

Internal recirculation in a moving droplet, enforced by the presence of fluid–fluid interfaces, plays an important role in several droplet-based microfluidic devices as it could enhance mixing, heat transfer, and chemical reaction. The effect of slip on droplet circulation is studied for two canonical steady-state problems: two-phase Couette, boundary-driven, and Poiseuille, pressure/body force...

In the present study, a compact analytical model is developed to determine the pressure drop of fully-developed, incompressible, and constant properties slip-flow through arbitrary cross-section microchannels. An averaged firstorder Maxwell slip boundary condition is considered. Introducing a relative velocity, the difference between the bulk flow and the boundary velocities, the axial momentum...

The rarefied gas effect on concentration slip and on heterogeneous combustion in microscale chemical reactors was investigated. First, a concentration slip model to describe the rarefied gas effect on the species transport in microscale chemical reactors was derived from the approximate solution of the Boltzmann equation. Second, the model was verified using the direct Monte-Carlo method for th...

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,...

Large-eddy simulations (LESs) of obstacle-free wakes, in a channel like geometry with an homogeneous transverse direction, are carried out in order to investigate the influence of confinement on turbulent wakes. The numerical solver makes use of a multi-domain Fourier–Chebyshev spectral method and the LES capability is implemented through a spectral vanishing viscosity technique. A top hat like...