[1] Results of an experimental investigation of the turbulent boundary layer in airflow over evolving young wind-waves are presented. The experiments were conducted in a laboratory wind-wave flume consisting of a closed-loop wind tunnel capable of generating wind speed that may exceed 15 m/s, atop of a 5 m long wave tank. Simultaneous measurements of mean wind velocity and of instantaneous fluc...

Cross correlations of the fluctuating wall-shear stress and the streamwise velocity in the logarithmic region of turbulent boundary layers are reported over 3 orders of magnitude change in Reynolds number. These results are obtained using hot-film and hot-wire anemometry in a wind tunnel facility, and sonic anemometers and a purpose-built wall-shear stress sensor in the near-neutral atmospheric...

the baroclinic adjustment is defined as the neutralization of the mean flow by eddies. with the amplitude growth of the baroclinic waves generated by an unstable mean flow, the eddy fluxes increase and act to reduce the meridional temperature gradient or vertical wind shear of the mean flow to subcritical value. this is believed to constitute the basic mechanism of baroclinic adjustment. the co...

Large-eddy simulation (LES) is used to investigate turbulence in a marginally-unstable stratified shear layer motivated by the observation of deep-cycle turbulence in the upper Equatorial Undercurrents. The initial condition consists of uniform shear and stratification profiles, and a constant gradient Richardson number Rig = 0.25. A constant wind stress forces turbulence in the upper surface l...

Momentum and scalar transport in the marine atmospheric boundary layer (MABL) is driven by a turbulent mix of winds, buoyancy, and surface gravity waves. To investigate the interaction between these processes, a large-eddy simulation (LES)model is developed with the capability to impose a broadband spectrum of time-varying finite-amplitude surface waves at its lower boundary. The LES model adop...

Airport surveillance radars (ASR) utilize a broad, cosecant-squared elevation beam pattern, rapid azimuthal antenna scanning, and coherent pulsed-Doppler processing to detect. and track approaching and departing aircraft. These radars, because of location, rapid scan rate, and direct air traffic control (ATe) data link, can also provide flight controllers with timely information on weather cond...

The growth of the atmospheric convective boundary layer (CBL) is forced mostly by buoyancy production at the surface. However, wind shear has a significant impact on the turbulence structure within the CBL and can contribute significantly to CBL growth when mean winds or wind shear in the lower atmosphere are strong and buoyancy flux from the surface and stratification in the free atmosphere ab...

Eyelashes are ubiquitous, although their function has long remained a mystery. In this study, we elucidate the aerodynamic benefits of eyelashes. Through anatomical measurements, we find that 22 species of mammals possess eyelashes of a length one-third the eye width. Wind tunnel experiments confirm that this optimal eyelash length reduces both deposition of airborne particles and evaporation o...