The fluidisation phenomenon is best explained by the balance of short and long range forces evaluated in a given powder assembly. The long range body forces include gravity, solid friction, buoyancy, interstitial fluid drag to include both the viscous (skin) friction and the form drag. The short-range forces, also known as particle surface-active forces can be due to physical (e.g. van der Waal...

In nature, microscopic surface textures impact useful function, such as the drag reduction of shark skin (Dean & Bhushan, 2010) and superhydrophobicity of the lotus leaf(Pan, Kota, Mabry, & Tuteja, 2013). In this study, we explore these phenomena by re-creating microscopic surface textures via the method of interfacial flow instability in drying polyvinylidene fluoride (PVDF) acetone solutions....

The ability of the three-dimensional Navier-Stokes method, PAB3D, to simulate the e ect of Reynolds number variation using non-linear explicit algebraic Reynolds stress turbulence modeling was assessed. Subsonic at plate boundary-layer ow parameters such as normalized velocity distributions, local and average skin friction, and shape factor were compared with DNS calculations and classical theo...

We combine three-dimensional descriptions of the movement patterns of the shoulder, elbow, carpus, third metacarpophalangeal joint and wingtip with a constant-circulation estimation of aerodynamic force to model the wing mechanics of the grey-headed flying fox (Pteropus poliocephalus) in level flight. Once rigorously validated, this computer model can be used to study diverse aspects of flight....

From their earliest origins, fishes have developed a suite of adaptations for locomotion in water, which determine performance and ultimately fitness. Even without data from behaviour, soft tissue and extant relatives, it is possible to infer a wealth of palaeobiological and palaeoecological information. As in extant species, aspects of gross morphology such as streamlining, fin position and ta...

Turbulence control in the form of a streamwise travelling wave transverse wall motion was studied numerically by employing direct numerical simulations (DNS). Both total and phase averaging were utilised to examine statistical behaviour turbulence affected forcing, with focus on skin friction. Comparison results from pure temporal spatial forcing are conducted, compilation data is used explore ...

The shifting status of transgender practices within the queer subculture has resulted in a renaissance of drag that has taken it into the mainstream culture of mass media, fine arts, and high fashion. Thus, Demi Moore has been featured in a suit and facial hair in an Arena magazine drag spread. Drag kings have also appeared prominently in such varied mainstream publications as Marie Claire, the...

The aim of this study was to compare the speed fluctuation and the drag force in young swimmers between genders. Twenty-three young pubertal swimmers (12 boys and 11 girls) volunteered as subjects. Speed fluctuation was measured using a kinematical mechanical method (i.e., speedo-meter) during a maximal 25-m front crawl bout. Active drag, active drag coefficient and power needed to overcome dra...

Flow control for turbulent skin-friction drag reduction is applied to a transonic airfoil improve its aerodynamic performance. The study based on direct numerical simulations (with up 1.8 billion cells) of the compressible flow around supercritical airfoil, at Reynolds and Mach numbers $Re_\infty = 3 \times 10^{5}$ $M_\infty =0.7$ . Control via spanwise forcing over fraction suction side airfoi...