Harvested by advanced technical systems honed over decades of research and development, wind energy has become a mainstream energy resource. However, continued innovation is needed to realize the potential of wind to serve the global demand for clean energy. Here, we outline three interdependent, cross-disciplinary grand challenges underpinning this research endeavor. The first is the need for a deeper understanding of the physics of atmospheric flow in the critical zone of plant operation. The second involves science and engineering of the largest dynamic, rotating machines in the world. The third encompasses optimization and control of fleets of wind plants working synergistically within the electricity grid. Addressing these challenges could enable wind power to provide as much as half of our global electricity needs and perhaps beyond.

Various wake status have been analysed by a numerical method that combines the actuator disc principle with the Navier–Stokes equations. Results are compared with one‐dimensional momentum theory and experiments. The computations are in excellent agreement with one‐dimensional momentum theory for rotors working in the windmill brake state as well as in the propeller and hover states. The computations demonstrate that the turbulent wake and vortex ring states are unstable regimes for a rotor with constant loading and that these states, after a complicated transient phase, settle to a steady state. Copyright © 1998 John Wiley & Sons, Ltd.

No abstract

No abstract

This paper shows a complete study of the dynamics of a mooring line: first, a numerical simulation code based on a lumped mass formulation was developed and tested under different setups and second, an equivalent experimental campaign was performed to compare against the numerical predictions. The tests