Opposition control of artificially initiated turbulent spots in a laminar boundary layer was carried out low-turbulence wind tunnel with the aim to delay transition turbulence by modifying structure within spots. The timing and duration control, which using wall-normal jets from spanwise slot, were pre-determined based on baseline measurements transitional layer. results indicated that high-spe...

An oscillating, weakly ionized surface plasma has been investigated for use in turbulent boundary layer viscous drag reduction. The study was based on reports showing that mechanical spanwise oscillations of a wall can reduce viscous drag due to a turbulent boundary layer by up to 40%. It was hypothesized that the plasma induced body force in high electric field gradients of a surface plasma al...

We consider here pulsatile flow in circular tubes of varying cross-section with permeable walls. The fluid exchange across the wall is accounted for by prescribing the normal velocity of the fluid at the wall. A perturbation analysis has been carried out for low Reynolds number flows and for small amplitudes of oscillation. It has been observed that the magnitude of the wall shear stress and th...

Light-weight and high strength alloys such as Al-Mg alloys are used in order to reduce the weight of industrial components. However these materials should be formed at elevated temperatures due to their poor formability at room temperature. Hot metal gas forming is one of the high-tech forming processes that is used to solve this problem. Recent investigation on tube hydroforming showed positiv...

Light-weight and high strength alloys such as Al-Mg alloys are used in order to reduce the weight of industrial components. However these materials should be formed at elevated temperatures due to their poor formability at room temperature. Hot metal gas forming is one of the high-tech forming processes that is used to solve this problem. Recent investigation on tube hydroforming showed positiv...

The effects of pressure gradient on an initially zeropressure-gradient turbulent boundary layer are investigated. We consider both adverse and favourable pressure gradients at matched Reynolds number as compared with the zero pressure gradient case. The data are also acquired using matched sensor parameters so that an unambiguous comparison can be made. The results show that energy increases th...

A period of deep inspiration in humans has been shown to attenuate subsequent bronchoconstriction, a phenomenon termed bronchoprotection. The bronchoprotective effect of deep inspiration may be caused though a depression in the force production of airway smooth muscle (ASM). We determined the response of whole airway segments and isolated ASM to a period of cyclic stretches. Isovolumetric contr...

This paper presents a spectral analysis of the response of a fluid containing bubbles to the motions of a wall oscillating normal to itself. First, a fourier series analysis of the RayleighPlesset equation is used to obtain an approximate solution for the nonlinear effects in the oscillations of a single bubble. This is used in the approximate solution of the oscillating wall problem and the re...

The effect of the spanwise discretisation on numerical calculations of the turbulent flow around a circular cylinder is systematically assessed at a subcritical Reynolds number of 10000 in the frame of three-dimensional large-eddy simulation. The eddy-viscosity k-equation subgrid scale model is implemented to evaluate unsteady turbulent flow field. Large-eddy simulation is known to be a reliabl...

Three-dimensional direct numerical simulations of the full compressible Navier–Stokes equations are performed for cavities that are homogeneous in the spanwise direction. The formation of oscillating spanwise structures is observed inside the cavity. We show that this 3D instability arises from a generic centrifugal instability mechanism associated with the mean recirculating vortical flow in t...