Form drag is a central process linking rough topography to ocean mixing processes. The history of the measurement of form drag in the ocean and atmosphere is reviewed. The basic equations governing form drag and its role in energy conversion are derived for a Boussinesq fluid, focusing on the case of tidal flow. Observational and numerical results are shown for stratified, tidal flow near a hea...

Relying on the rugosity effect, we analyse the drag minimization problem in relation with the micro-structure of the surface of a given obstacle. We construct a mathematical framework for the optimization problem, prove the existence of an optimal solution by Γ-convergence arguments and analyse the stability of the drag with respect to the micro-structure. For Stokes flows we justify why rugosi...

Measurements and calculations of Coulomb drag between two low density, closely spaced, two-dimensional electron systems are reported. The experimentally measured drag exceeds that calculated in the random phase approximation by a significant, and density dependent, factor. Studies of the dependence of the measured drag on the difference in density between the two layers clearly demonstrate that...

The Coulomb drag in a system of two parallel layers is the result of electron-electron interaction between the layers. We have observed reproducible fluctuations of the drag, both as a function of magnetic field and electron concentration, which are a manifestation of quantum interference of electrons in the layers. At low temperatures the fluctuations exceed the average drag, giving rise to ra...

The inconsistency for the calculated high drag on an actively swimming dolphin and underestimated muscle power available resulted in what has been termed Gray's paradox. Although Gray's paradox was flawed, it has been the inspiration for a variety of drag reduction mechanisms. This review examines the present state of knowledge of drag reduction specific to dolphins. Streamlining and special be...

Drag-and-drop (DND, for short) is an operation in applications with graphical user interfaces by which users can request, in a visual way, that running applications exchange data with each other. To the user, in a drag-and-drop operation, it appears that data is being dragged from the source of the drag to the destination of the drag. Because applications are independent of each other and writt...

in this study, changes in speed and turbulence intensity in the wake of a peugeot model and the drag coefficient changes with increases vehicle speed in unsteady flow measured and evaluated. the blow open circuit wind tunnel to simulate fluid flow is used. disturbances and nominal maximum speed of the device, respectively is, 30 m / s and 0.01%. has been continuously increasing speed by an inve...

this paper studied the mathematical method of flow with regard to two-phase boundary layer that created over the iced surface. based on experimental results, skin drag over the iced surface compared with this force that compute with slip condition. based on this results, for iced surface blasius equation solving at non-slip condition, can replace with solving the blasius equation with slip cond...

in order to design and manufacturing some postharvest equipment, determination of some hydrodynamic properties of crops are necessary. the quality of products in global and local markets can be increased by applying these properties and receive economical benefits. for these purpose, two local varieties of apples in the east azerbaijan province, iran(asheghi and gare yapraq)were selected.ashegh...

Stresses at the surface and at depth are calculated for a stretch of Byrd Glacier, Antarctica. The calculations are based on photogrammetrically determined velocities and elevations, and on radio-echo-determined ice thicknesses. The results are maps of drags from each valley wall, of normal forces laterally and longitudinally. and of basal drag. Special challenges in the calculation are the num...