It is known that vortex rings formed by large stroke ratios ~in a piston/cylinder arrangement! pinch off from their generating jets at a fairly constant universal time scale. In this paper we show that the hypothesis that at the pinch off the translational velocity of the ring equals the jet flow velocity near the ring is equivalent to the recently proposed idea based on a variational principle...

SWCNT can be conceptualized by wrapping a one-atomic-layer thick graphene into a hollow cylinder. As shown in Figure 1, the wrapping way is represented by the chiral vector (n, m), which denote the number of unit vectors along two directions in the crystal lattice of graphene sheet.1 Because of the symmetry and unique electronic structure of graphene, the structures of SWCNTs strongly affect th...

Water repellency of hairy surfaces depends on the geometric arrangement of these hairs and enables different applications in both nature and engineering. We investigate the mechanism and optimization of a hairy surface floating on water to obtain its maximum load-carrying capacity by the free energy and force analyses. It is demonstrated that there is an optimum cylinder spacing, as a result of...

The purpose of this paper is to study the effect of presence of fluid within and around a poroelastic circular cylindrical shell of infinite extent on axially symmetric vibrations. The frequency equation each for a pervious and an impervious surface is obtained employing Biot’s theory. Radial vibrations and axially symmetric shear vibrations are uncoupled when the wavenumber is vanished. The pr...

The radially outward flow of fluid into a porous medium occurs in many practical problems, from transport across vascular walls to the pressurization of boreholes. As the driving pressure becomes non-negligible relative to the stiffness of the solid structure, the poromechanical coupling between the fluid and the solid has an increasingly strong impact on the flow. For very large pressures or v...

. Tendon sheaths are complex tubes wrapped completely around tendons. They are placed between two movable tissues to diminish friction when tendons pass either under ligaments or retinacula or pass through fascial slings or osseofibrous tunnels. The aim of this study was to show that the El2 plastination technique is a useful research tool for demonstrating different anatomical structures, e.g....