A fundameatal requirement of any parametrization of sub-gridscale orography (SSO) is that the total (resolved plus pa,rametrized) drag on a mountain rarge should be independent of the model horizontal resolution. However, parametrizations are typically developed and tested (ar:d inevitably tuned) for a single model resolution and so this issue tends not to be addressed. In ihis study, this issu...

1. Motivation and objectives We develop flow modeling and optimization techniques using biologically inspired algorithms such as neural networks and evolution strategies. The applications presented herein encompass a variety of problems such as cylinder drag minimization, neural net modeling of the near wall structures, enhanced jet mixing, and parameter optimization in turbine blade film cooli...

A turbulent axisymmetric bluff body wake is investigated using large eddy simulation to uncover key flow dynamics and structures. The effect of low-frequency high-frequency pulsed jet forcing at the point separation studied reveal underlying mechanisms involved in base pressure changes, which provide a reference for drag reduction active control.

We make use of the AdS/CFT correspondence to determine the energy of an external quark-antiquark pair that moves through strongly-coupled thermal N = 4 super-Yang-Mills plasma, both in the rest frame of the plasma and in the rest frame of the pair. It is found that the pair feels no drag force, has an energy that reproduces the expected 1/L (or γ/L) behavior at small quarkantiquark separations,...

Configurations derived from classical concepts of waverider and Busemann biplane have great potential of use in aerodynamic design of highspeed vehicles with air-breathing jet engines due to their ability to provide both high lift-to drag ratio and intense preliminary compression of the flow before air intakes. The issues of conceptual design of highspeed vehicles based on the use of waverider ...

The frictional drag between parallel two-dimensional electron systems has been measured in a regime of strong interlayer correlations. When the bilayer system enters the excitonic quantized Hall state at total Landau level filling factor nu(T) = 1, the longitudinal component of the drag vanishes but a strong Hall component develops. The Hall drag resistance is observed to be accurately quantize...

We show that Mach-like correlations from heavy quark jets in the Gubser et al AdS/CFT string drag model arise not from the expected (weak) hydrodynamical Mach sound wakes zone but from a near “Neck” zone where strong chromo-viscous field effects dominated and lead to a distinctive stress in the plasma of the form T Neck ∝ √ λT 2 0 Y (x)/x. We propose that measurement of the jet velocity depende...

Ten prominent dimethoxyphenols were determined in birchwood smoke from choked and open laboratory burning and in chimney smoke from a tiled stove. The structures of the methoxyphenols are similar to those of the well-known tocopherol and ubiquinol antioxidants. The 2,6-dimethoxyphenols characterising hardwood smoke are stronger antioxidants than the corresponding 2-methoxyphenols present mainly...

there are different methods to reduce drag in high speed hulls. one of these methods is a change in the shape of the body by adding longitudinal side tunnels. in this paper it has been attempted to determine the influence of the tunnel height on hydrodynamic characteristics of the hull to achieving an optimum shape for the tunnel. to achieve this purpose, numerical simulation of the problem has...