Using two-dimensional hydrodynamical simulations, we investigate the interaction of a collimated fast wind (CFW) interacting with a spherical asymptotic giant branch (AGB) wind as the mechanism for shaping proto-planetary nebulae and young planetary nebulae. In particular, we compare our simulations to the observations of an evolved PPN with multiple, highly collimated lobes, CRL 618. We charac...

As a wind turbine extracts energy from the wind, induced wind velocities, lower than the freestream velocity, will be present both upstream and downstream of the rotor. In this study, the upstream induction zone of a 225 kW horizontal axis Vestas V27 wind turbine located at the Danish Technical University’s Risø campus is investigated using a scanning Light Detection and Ranging (lidar) system....

Six-yr-long time series of winds, waves, and water velocity from a cabled coastal observatory in 12 m of water reveal the separate dependence of the cross-shelf velocity profile on cross-shelf and along-shelf winds, waves, and tides. During small waves, cross-shelf wind is the dominant mechanism driving the cross-shelf circulation after tides and tidal residual motions are removed. The along-sh...

Retrieval of wind fields from a single-Doppler lidar with small azimuthal sectors is challenging. Both simpler retrieval algorithms such as Velocity Azimuth Display (VAD) or Volume Velocity Processing (VVP), and more sophisticated techniques such as Four Dimensional Variational Analysis (4DVAR) using VAD for mean velocities have limitations on small sectors of data. Narrow datasets may result i...

A mathematical model is used to simulate the effect of wind conditions on men's and women's 200-m times. Four questions are posed: What is the effect of constant winds on 200-m performance? What is the effect of varying wind speed and direction? What is the effect of the lane allocation? How do wind conditions affect the velocity profile? The race is simulated for winds with constant velocity a...

According to the shortcomings of the existing ultrasonic wind velocity measurement device, for instance, complexity of circuit and difficulty of signal processing, a new ultrasonic wind velocity measurement is put forward based on phase discrimination and a new sensor configuration as well. Thus, a system model is built. Firstly, an equilateral triangle should be constituted by an ultrasonic em...

Building integrated photovoltaic/thermal (BIPV/T) systems serve two purposes – generate electricity and heat ambient air using absorbed solar energy. High wind velocity reduces the efficiency of unglazed transpired solar collectors (UTC). Indeed, wind flow on the collector’s surface reduces the useful heat transferred to the plenum air by effectuating convection losses and suction in the pores;...

The aerodynamic behavior of a 48’ yacht rig 3D scale model was characterized by means of wind tunnel tests. The experimental program, performed in the Politecnico di Milano Twisted Flow Wind Tunnel, allowed the aerodynamic forces to be characterized using forced motion tests and the aeroelastic behavior of the sail plan to be studied. Preliminary results are presented with reference to the typi...

Air-sea exchange of CO2 is parameterized along the cruise track of Galathea 3 – a worldwide research expedition. A key parameter is the gas transfer velocity, which varies with wind speed. Wind speeds are measured continuously on board the research vessel. For selected areas, winds are also retrieved from Envisat ASAR images, as the ASAR senses small-scale waves at the sea surface generated by ...