EFFECT OF SPATIAL VARIATION OF A WAVE FIELD ON THE RESULTING RIPPLE CHARACTERISTICS AND COMPARISON TO PRESENT RIPPLE PREDICTORS

摘要

Laboratory experiments analyzed herein focus on the validity of ripple predictors under spatially variable wave envelopes. Present-day ripple predictors commonly derived from laboratory data (for smaller wave periods of about 1 to 4 s) within which only small regions of the facilities were used to observe and measure the sand ripple geometric characteristics of the nearly progressive waves measured overhead. When extended to large sediment test sections, our results show that the predictors are still valid along the tank under wave conditions which have significant wave envelope spatial variation (e.g., standing waves), provided that ripple predictors use the wave measurements directly above the respective locations within the computations. Results indicate that even under the case of mild reflection, noticeable variation in ripple characteristics can be seen along the sediment test section; thus, compels the necessity of measuring the wave field along the entire sediment section to achieve accurate results.