In this study, horizontally periodic large eddy simulations (LES) are utilized to study turbulent atmospheric boundary-layer flow over wind turbines in the far-downstream portion of a large wind farm where the wakes have merged and the flow is fully developed. In an attempt to increase power generation by enhancing the mean kinetic energy (MKE) entrainment to the wind turbines, hypothetical syn...

We study the generation of surface waves on water as a bifurcation phenomenon. For a critical wind-speed there appear traveling wave solutions. While linear waves do not transport mass (in the mean), nonlinear effects create a shear-flow and result in a net mass transport in the direction of the wind. We derive an asymptotic formula for the average tangential velocity along the free surface. Nu...

Introduction. Individual cigarettes are point sources of air pollution; smoking in groups becomes an area source. Outdoor air pollutants from individual point sources are subject to plume rise if the temperature of the smoke plume is hotter than the surrounding air; however if the plume has a small cross-section, as for a cigarette, it will rapidly cool and lose its upward momentum, and then wi...

An experimental study was conducted to investigate on the effects of the relative rotation directions of two tandwm wind turbines on the power production performance and flow characteristics in the wakes of two wind turbines in tandem. The experimental study was performed in a large-scale Aerodynamics/tmospheric Boundary Layer (AABL) Wind Tunnel located at the Aerospace Engineering Department o...

The wind energy is considered to be one of the poor quality energies due to the variation of the velocity and direction of the wind. These variations cause fluctuations in the input power and the frequency, thereby affecting the operation of the system. At a given wind velocity, the mechanical power available from a wind turbine is a function of its shaft speed. The shaft speed is varying due t...

Wind environment in the populated built area especially in campus is important. This s tudy tes ted57 crossroad spots over of the whole campus in North China University of Technology (NCUT). The data of wind speed and direction were measured at fixed time and fixed place. The average, maximum values as well as the speed variation scale were calculated. Wind comfort criteria were adopted t...