Why do turbines on the same ridge produce different power?

Wind speed grows with height above the ground (wind shear, modelled here as a power law) and terrain shape locally accelerates or shelters the flow (orographic speed-up on a crest, deceleration in a valley or lee slope). Because power scales with the cube of wind speed, even a small local speed difference changes output a lot.

What is a fractional speed-up ratio (FSU)?

It is the fractional change in wind speed caused by terrain relief, used in wind-siting standards such as IEC 61400-1's complex-terrain annex. Ridge crests typically see a positive FSU (faster wind), while valleys and lee slopes see a negative or near-zero FSU.

Home▸Energy & Thermodynamics▸Wind Turbine Field: Terrain Shear & Ridge Speed-Up (2D)

Wind Turbine Field: Terrain Shear & Ridge Speed-Up (2D)

Five turbines sit at different points on the same ridge — valley, windward slope, crest, lee slope, second valley. A wind-shear power law and a site-specific orographic speed-up model show why they never produce the same power, even in identical wind.

Energy & Thermodynamics2DModerate60 FPS📱 Mobile-adapted⇄ 3D version

This 2D companion keeps the 3D scene's hilly wind farm but replaces its decorative flythrough with the two effects that actually decide how much a real turbine produces on that kind of terrain: wind shear, the power-law growth of wind speed with height above ground, and orographic speed-up, the local acceleration or sheltering a ridge profile imposes on the flow. Five turbines sit at fixed points along one ridge wavelength — two valleys, a windward slope, the crest and a lee slope — and because power scales with the cube of wind speed, the same reference wind still produces a clearly different kilowatt reading at each site.

⚙ Under the hood

Power-law wind shear (v ∝ height^α) combined with a per-site fractional speed-up ratio (IEC 61400-1 style orographic correction) sets each turbine's local hub-height wind speed; a standard cubic power curve with cut-in/rated/cut-out limits then converts that speed to kilowatts.

wind shearorographic speed-uppower curvewind farm sitingboundary layerterrain

2D · HTML5 Canvas 2D · 60 FPS target · runs fully client-side, no install