In this study, a two-dimensional numerical model(NEWFLUME) is applied to investigate the shear stressdistributions in the bubbly flow on a sloping beach (1/20) underbreaking waves. The numerical model solves the Reynoldsequations for mixture flow and employs the volume-of-fluid(VOF) method to track the free surfaces. Turbulence closure isaccomplished by the k scheme. An improved airentrainment model is incorporated to consider the effect ofbubbles on the mean flow in present model. The bed stressdistributions and the effect of bubbles on shear stress areinvestigated. It is found that the bed stress decreases by theexistence of bubbles in the aeration region. The maximum valueof time dependent total shear stress is damped approximately12% and the depth integrated total shear stress shows a 20%decrement.
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