The way schooling fish swim reveals how to squeeze more power from the wind over a given area of land.
A Caltech (Pasadena) team lead by Bob Whittlesey believe principles learned from the dynamics of schooling fish can significantly increase the packing density of wind farms using vertical axis turbines. Whereas the more common (and individually more efficient) horizontal wind turbines need to be widely spaced because the turbines impede the airflow around them, vertical wind turbines can increase airspeed around them by forming a 'Karman vortex street'. In nature, these vortices help synchronize schools of fish and reduce the power each fish needs to expend.
Karman vortex streets often cause engineering challenges such as vibration. In this case, the Caltech model suggests the dynamic nature of the vortices can increase the power density of a vertical wind turbine array by more than 10-fold.
Animations of Karman vortex streets can be viewed at http://www2.icfd.co.jp/menu1/karmanvortex/karman.html. The Caltech paper can be downloaded at Fish schooling as a basis for vertical axis wind turbine farm design.
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