THE CRITERION OF RIPPLE FORMATION BY WAVE ACTION

Abstract

In this paper, we emphasize that there must exist a common mechanism governing ripple formation in the case of both waves where the acceleration effect exists, and unidirectional flow, where the acceleration effect is usually ignored. Using a light sediment with an immersed specific gravity of about 0.8, which is nearly one-half that of natural sand, a series of ripple formation experiments were performed in order to determine the formation criterion. Using the experimental data, along with data collected by other researchers the ripple-formation criterion was investigated in terms of the ratio of water particle orbital diameter to sediment grain diameter as an acceleration parameter, on the so-called Shields diagram. Emphasis is placed on the importance of this ratio in the criterion of ripple formation in relation to that by unidirectional flow.