Preliminary application of hot-film wall shear stress sensor under breaking waves

The knowledge of the bed shear stress under breaking waves is essential for understanding the sediment transport and beach morphology in the surf zone. The turbulence and vortexes generated by breaking waves have a significant effect on the bed shear stress. Application tests of the bed shear stress measurement under breaking waves by the MEMS flexible hot-film shear stress sensor are conducted in a wave flume. The experimental results show that the sensor can be applied to the measurement of the bed shear stress under breaking waves. Before the breaking point, the direction of the bed shear stress can be determined by the near-bed velocity. The change of the bed shear stress is gentle before wave breaking. The fluctuations and the peak value of the bed shear stress increase after wave breaking. The extreme value of the average maximum bed shear stress along the slope appears after the plunging point.