Physical modeling of vanishing bores in open-channel flows

Abstract

When an undular bore is propagating upstream against a subcritical flow in a flat channel, its leading front may weaken and vanish. The present study physically investigated the whole decaying process of vanishing bores in a relatively large facility. The invert was made of mobile or fixed natural river gravels. Detailed sampling of water surface elevations and velocities was performed in combination with high-resolution photo and video recordings. Despite some increased turbulence characteristics linked to the bore front arrival, no sediment motion was observed underneath the vanishing bores. The quantitative results provide a unique benchmark data set for further study of the later-stage bore propagations.