Advance in bed shear stress under waves

The bed shear stress under the action of waves is one of the important essential parameters to estimate the incipient motion and transport of offshore sediment, and its bottom friction effect will also have an impact on the offshore hydrodynamic environment. Due to the difficulty in field observation, the understanding of the wave boundary layer and the bed shear stress under the action of waves is mainly based on indoor experimental observation. This paper reviews the relevant theoretical models and experimental measurement research at home and abroad, sorts the advantages and disadvantages of various research methods and measurement techniques, as well as the application conditions, collates a lot of experimental data from 1970s to now, generalizes and analyzes the existing research results, including the impact of wave nonlinearity, wave breaking and other factors on the bed shear stress, summarizes the limitations of the existing research, and puts forward the future research focuses. Super-large water flume is an important facility to break through the bottleneck in the theoretical study of the layer of wave boundary in the future. The development of high-adaptability underwater two-dimensional shear stress sensor is the key to making a breakthrough in the study of bed shear stress under complex dynamic conditions.