Fan, J.; Zheng, J.; Tao, A.; Yu, H, and Wang, Y, 2016. Experimental study on upstream-advancing waves induced by currents. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 846–850. Coconut Creek (Florida), ISSN 0749-0208.
Due to the widespread existence of large-scale continuous submarine sandbars the coasts and estuaries, the interaction between the ambient current and this kind of topography is important and complicated. It has been known that regular free surface waves can be generated and propagate in the upstream direction, when a steady current with specific depth and velocity flows past the fixed periodic wavy bottoms with large steepness. This particular free surface response, called the upstream-advancing wave, has drawn attention in the past few decades but still lacks detailed quantitative study identifying the critical conditions and the generation mechanism. A series of experiments in a large-sized flume were designed and performed to obtain the critical flow condition corresponding to the most intensive upstream-advancing waves. The wavy bottoms were formed by eight continuous fixed sinusoidal corrugated wood surfaces with wave steepness of 0.33. Wave height distributions were measured by adjusting the relative water depth (the ratio of the water depth to the bottom wavelength, 0.5–1.1, seven groups) and Froude number (0.15–0.35, 21 cases in each group). These distributions presented a unimodal pattern generally. It indicates that the critical relative water depth was 0.8 and the corresponding critical Froude number was 0.26. Once the waves were triggered, the wave periods concentrated on a small range between 1.2 s and 1.4 s. Wavelengths kept basically invariable along the propagating path.