The efficiency of conversion of electrical power into fluidic power in an electrohydrody-namic (EHD) pump depends on the bulk fluid velocity. An analytical formulation is developed for calculation of the efficiency of an EHD pump, with and without the presence of a superimposed flow due to an externally imposed pressure gradient. This formulation is implemented into a numerical model, which is ...

The glide is a major part of starts, turns and the stroke cycle in breaststroke. Glide performance, indicated by the average velocity, can be improved by increasing the glide efficiency, that is, the ability of the body to minimise deceleration. This paper reviews the factors that affect glide efficiency. In the first part of the review the sources of resistive force are reviewed including surf...

A simple pressure-based feedback control strategy for wall-transpiration control of incompressible unsteady two-dimensional channel flow was recently investigated by Aamo, Krstic & Bewley (2003). Nonlinear two-dimensional channel flow simulations which implemented this control strategy resulted in flow transients with instantaneous drag far lower than that of the corresponding laminar flow. The...

This paper discusses the use of control theory for optimum design of aerodynamic configurations. Examples are presented of the application of this msethod to the reduction of shock induced pressure drag on airfoils in two-dimensional transonic flow.

In the off-equatorial region of Jupiter’s and Saturn’s atmospheres, baroclinic eddies transport angular momentum out of retrograde and into prograde jets. In a statistically steady state, this angular momentum transfer by eddies must be balanced by dissipation, likely produced bymagnetohydrodynamic (MHD) drag in the planetary interior. This paper examines systematically how an idealized represe...

Abstract. Much of the work on flow through porous media, especially with regard to studies on the flow of oil, are based on “Darcy’s law” or modifications to it such as Darcy-Forchheimer or Brinkman models. While many theoretical and numerical studies concerning flow through porous media have taken into account the inhomogeneity and anisotropy of the porous solid, they have not taken into accou...

Abstract. Much of the work on flow through porous media, especially with regard to studies on the flow of oil, are based on “Darcy’s law” or modifications to it such as Darcy-Forchheimer or Brinkman models. While many theoretical and numerical studies concerning flow through porous media have taken into account the inhomogeneity and anisotropy of the porous solid, they have not taken into accou...

Commercial transports as well as fighter aircraft of the future are being designed with very low drag (friction and pressure). Concurrently, commuter airports are being built or envisioned to be built in the centers of metropolitan areas where shorter runways and/or reduced noise footprints on takeoff and landing are required. These requirements and the fact that drag is lower on new vehicles t...

Many fish species transform in body shape during growth, but it remains unclear how this influences the mechanics of locomotion. Therefore, the present study focused on understanding how drag generation during coasting is affected by ontogenetic changes in the morphology of zebrafish (Danio rerio). The shapes of the body and fins were measured from photographs of fish ranging in size from small...

Pressure drags, obtained from measured pressure distributions in the transonic and low-supersonic speed range, are compared for sharp and blunt leading-edged two-dimensional aerofoils. For the special blunt shapes considered here, the high pressures in the stagnation-point region are offset by low pressures generated further round on the leading edge and on the basic aerofoil itself. The result...