Experimental Studies on the Characteristics of Near-bottom Flow in the Current with Waves

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The Summary of this research results is as follows :(1) The steady flow component in the current with waves was theoretically analyzed by using a three-layr eddy viscosity model near the bottom boundary layr. Moreover, a simple method to estimate the important parameters contained in the analytical solution was presented. The analytical solutions almost agreed with the experimental results.(2) The theoretical solution of the wave flow component in the current with waves was obtained by using a two-layr eddy viscosity model, in which the eddy viscosity in the wave boundary layr increased quadratically with the height above the bottom and that outside the wave boundary layr constant. The theoretical and experimental values almost agreed.(3) The analytical values of shear stress in the current with waves were obtained from the theoretical solutions of the steady and wave flow components. The variations of the bottom shear stress with wave phase and the influences of wave motion on the bottom shear stress were clarified from the analytical results of shear stress.(4) The phase difference of the wave flow component in the current with waves inside and outside the wave boundary layr was maximum at the bottom. The maximum value of phase difference ranged between 40ﾟ and 48ﾟ for the present experimental conditions.(5) The resuspension rate of the bottom sediment in the current with waves for the present experimental conditions was about 20% to 30% bigger than that in the current. The variations of the resuspension rate of the bottom sediment with the wave height under a constant velocity were bigger than those with the magnitude of velocity under a constant wave height.