This study numerically investigated heat transfer and fluid flow characteristics in a novel cylindrical heat sink with helical minichannels for the laminar flow of fluid with temperature-dependent properties. A finite volume method was employed to obtain the solution of governing equations. The effects of helical angle, channel aspect ratio, and Reynolds number, which were regarded as main para...

In this paper, a numerical study on pressure characteristics of fluid passing through a configuration of sudden expansion with central restriction only and sudden expansion with central restriction and fence has been carried out. The two dimensional steady differential equations for conservation of mass and momentum are solved for Reynolds number ranging from 50 to 200, percentage of central re...

We report a photoresist offset method using gray-scale technology to counteract the effect of aspect ratio dependent etching (ARDE), achieving controlled etch depths across a range of aspect ratios. Previously, we have reported the first fabrication of a deep phase Fresnel lens (PFL) in silicon through the use of gray-scale technology. As each PFL ridge becomes thinner at larger radii of the PF...

We present experimental results for pattern formation in Rayleigh-Bénard convection with modulated rotation about a vertical axis. The dimensionless rotation rate Omega was varied as Omega(m)=Omega[1+delta cos(phi Omega t)] (time is scaled by the vertical viscous diffusion time of the cell). We used a cylindrical cell of aspect ratio (radius/height) Gamma=11.8 and varied Omega, delta, phi, and ...

The optical properties of Al nanostructures are investigated by means of time dependent density functional theory, considering chains of varying length and ladders/stripes of varying aspect ratio. The absorption spectra show redshifting for increasing length and aspect ratio. For the chains the absorption is dominated by HOMO → LUMO transitions, whereas ladders and stripes reveal more complex s...

Space-time correlations or Eulerian two-point two-time correlations of fluctuating velocities are analytically and numerically investigated in turbulent shear flows. An elliptic model for the space-time correlations in the inertial range is developed from the similarity assumptions on the isocorrelation contours: they share a uniform preference direction and a constant aspect ratio. The similar...

RÉSUMÉ. Les travaux proposés dans cette communication s’inscrivent dans une démarche générale de génération semi-automatique d’usinage de poches dans le domaine aéronautique. Nous nous intéressons plus spécifiquement à l’aide au choix de stratégie d’usinage pour une géométrie de poche dans un contexte d’Usinage à Grande Vitesse (UGV). Après avoir défini des critères géométriques permettant la c...