Transport of dissolved oxygen at the sediment-water interface in the spanwise oscillating flow

The distribution and concentration of dissolved oxygen(DO)play important roles in aerobic heterotroph activities and some slow chemical reactions,and can affect the water quality,biological communities,and ecosystem functions of rivers and lakes.In this work,the transport of high Schmidt number DO at the sediment-water interface of spanwise oscillating flow is investigated.The volume-averaged Navier-Stokes(VANS)equations and Monod equation are used to describe the flow in the sediment layer and the sediment oxygen demand of microorganisms.The phase-averaged velocities and concentrations of different amplitudes and periods are studied.The dependence of DO transfer on the amplitude and period is analyzed by means of phase-average statistical quantities.It is shown that the concentration in the sediment layer is positively correlated with the turbulence intensity,and the DO concentration and penetration depth in the sediment layer increases when the period and amplitude of the oscillating flow increase.Moreover,in the presence of oscillating flow,a specific scaling relationship exists between the Sherwood number/oxygen consumption of aerobic heterotrophs and the Reynolds number.