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A ship in a force 12 ("hurricane-force") storm at sea, the highest rated on the Beaufort scale. The Beaufort scale (/ ˈ b oʊ f ər t / BOH-fərt) is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale.
The apparent wind on the sail creates a total aerodynamic force, which may be resolved into drag—the force component in the direction of the apparent wind—and lift—the force component normal (90°) to the apparent wind. Depending on the alignment of the sail with the apparent wind, lift or drag may be the predominant propulsive component.
Drag coefficients in fluids with Reynolds number approximately 10 4 [1] [2] Shapes are depicted with the same projected frontal area. In fluid dynamics, the drag coefficient (commonly denoted as: , or ) is a dimensionless quantity that is used to quantify the drag or resistance of an object in a fluid environment, such as air or water.
When wind is blowing over a water surface, the wind applies a wind force on the water surface. The wind stress is the component of this wind force that is parallel to the surface per unit area. Also, the wind stress can be described as the flux of horizontal momentum applied by the wind on the water surface. The wind stress causes a deformation ...
The force F is generated by the wind's interaction with the blade. The magnitude and distribution of this force is the primary focus of wind-turbine aerodynamics. The most familiar type of aerodynamic force is drag. The direction of the drag force is parallel to the relative wind.
In sailing, apparent wind is the speed and direction of wind indicated by a wind instrument on a moving craft (on water, land or ice) in undisturbed air. It is composed of the combined speeds and directions of the craft and wind observed by a stationary wind instrument—the true wind. A true wind coming from the bow increases the apparent wind ...
The geostrophic wind component is the result of the balance between Coriolis force and pressure gradient force. It flows parallel to isobars and approximates the flow above the atmospheric boundary layer in the midlatitudes. [ 4 ]
The lift force is transmitted through the pressure, which acts perpendicular to the surface of the airfoil. Thus, the net force manifests itself as pressure differences. The direction of the net force implies that the average pressure on the upper surface of the airfoil is lower than the average pressure on the underside. [60]