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Pressure differences result from the normal force per unit area on the sail from the air passing around it. The lift force results from the average pressure on the windward surface of the sail being higher than the average pressure on the leeward side. [1] These pressure differences arise in conjunction with the curved air flow.
In fluid dynamics, the lift coefficient (C L) is a dimensionless quantity that relates the lift generated by a lifting body to the fluid density around the body, the fluid velocity and an associated reference area. A lifting body is a foil or a complete foil-bearing body such as a fixed-wing aircraft.
The magnitude, denoted by S, divided by the speed of light is the density of the linear momentum per unit area (pressure) of the electromagnetic field. So, dimensionally, the Poynting vector is S = power / area = rate of doing work / area = ΔF / Δt Δx / area , which is the speed of light, c = Δx / Δt, times ...
The lift force L on a wing of area A, traveling at true airspeed v is given by =, where ρ is the density of air, and C L is the lift coefficient. The lift coefficient is a dimensionless number that depends on the wing cross-sectional profile and the angle of attack . [ 12 ]
Air above the airfoil is pushed toward the center of the low-pressure region, and air below the airfoil is pushed outward from the center of the high-pressure region. According to Newton's second law, a force causes air to accelerate in the direction of the force. Thus the vertical arrows in the accompanying pressure field diagram indicate that ...
Force on a sail results from reflecting the photon flux. The force on a sail and the actual acceleration of the craft vary by the inverse square of distance from the Sun (unless extremely close to the Sun [26]), and by the square of the cosine of the angle between the sail force vector and the radial from the Sun, so
is the static pressure at the point at which pressure coefficient is being evaluated is the static pressure in the freestream (i.e. remote from any disturbance) is the freestream fluid density (Air at sea level and 15 °C is 1.225 /)
For thousands of years ship designers and builders of sailing vessels used rules of thumb based on the midship-section area to size the sails for a given vessel. The hull form and sail plan for the clipper ships, for example, evolved from experience, not from theory. It was not until the advent of steam power and the construction of large iron ...