The Effect of Wave-damping on the Surface Velocity of Water in a Wind Tunnel

Abstract

SummaryA laboratory wind tunnel has been used to study the movement of the surface of a body of water over which a wind is blowing. The ratio of the surface velocity Us to the wind velocity V has been measured for both smooth and wavy surfaces at wind speeds between 350 and 750 cm/s. It has been found that this ratio is markedly affected by the damping-out of surface waves. For a wavy surface, as obtained with clean water, us/V has a constant value of about 0·03. The damping of the surface waves is achieved by the addition of detergent solution to the water. There is a particular concentration of detergent, and a corresponding surface pressure, at which u s/ V ceases to have this constant value and begins to rise to' values around 0·045. For a fully damped surface us/V rises linearly with V for low wind speeds and tends to a constant value of 0·045 for wind speeds greater than 550 cm/s. These findings are, to some extent, in conflict with the observations and theories of previous workers.

The Response of Closed Channels to Wind Stresses

“…The surface velocities induced when wind blows over closed channels or water storages in turbulent flow have been measured by Keulegan (1951), van Dorn (1953, Francis (1953), Vines (1962), andFitzgerald (1964). All these results may be summarized in the form Us = aV, (8) where a is a coefficient varying slightly with the Reynolds number, and V (cmjs) is the wind velocity measured at some reference height above the water surface.…”

Factors affecting the use of monomolecular surface films to control oil pollution on water

“…Of the many physical processes which cause motion of surface water, wind usually is the most influential. According to Fitzgerald (1964), a clean wave-covered water surface moves at a speed which is about 1/30 that of wind. This ratio of the rate of surface movement to wind velocity (ps/V) was independent of wind speed.…”