Measurements of particle velocities in laboratory-scale random waves

Étude par vélocimétrie Doppler laser du champ des vitesses instantanées dans une houle produite en laboratoire

“…Elle nous permet d'obtenir un coefficient de réflexion moyen de l'ordre de 6 %. Chiffre voisin de celui obtenu au laboratoire de Liverpool lors des essais d 'Anastasiou (1982) dans un canal de section voisine.…”

“…La seule technique actuellement exploitable pour ce type d'étude est la vélocimétrie Doppler à laser (VOL), et Anastasiou, Tickel et Chapun (1982) ont déjà abordé ce problème dans le cas de mesure en continu dans une houle aléatoire.…”

Irregular Wave‐Induced Velocities in Shallow Water

“…Both Tayfun's and St. Denis's methods may be applicable to wave particle velocities but such an investigation is beyond the scope of this thesis. Anastasiou, Tickell and Chaplin (1982) reported that the statistical distribution of both horizontal and vertical particle velocities follow a Gaussian form for points measured more than half a significant wave height below the mean water level. The measurements of velocities were made with a laser Doppler velocimeter (LDV) under irregular waves in a wave tank.…”

“…The sea surface elevation, q(x, t), of a linear, partially reflected, unidirectional wave on a flat bottom can be expressed as (Dean and Dalrymple 1984) 7(x, t) = a cos(kx -ut) + aK, cos(kx + ot + 0) (1) where a = amplitude of the incident wave, k = wave number, (= 27r/L, where L is wave length) x = horizontal position, a = angular wave frequency (= 27r/T, where T is wave period), t = time, K, = reflection coefficient (= aincident/areflect,•d), and 9 = phase shift due to reflection.…”