EXPERIMENTAL STUDY ON CRITICAL RESONANT STATE OF UPSTREAM-ADVANCED WAVES

It is known that the upstream-advancing waves can be excited when a steady current travelling over a wavy bottom. While the generation mechanisms are still inconclusive and the related dynamic and kinematic characteristics of the excited water waves are not clear. Focusing on the dynamics of this kind of upstream-advancing waves, especially the critical generation conditions, a series of experiments were carried out in a wave-current-wind flume (80m*1.0m*1.5m) with fixed sinusoidal bottom corrugations. By varying the current velocity and relative water depth, altogether 137 cases were realized. It is found that there exist a region of the current velocity for the exciting of upstream-advancing waves, based on the whole processes recorded, from the pure current to the present of clear upstream-advancing waves to the disappear of the evident waves again. The most unstable conditions correspond to the largest wave amplitudes were investigated in details. The dynamics of the excited waves were analyzed primarily for understanding of the generation mechanisms.