We performed laboratory experiments to investigate the influence of sand content on the dynamics of wave‐supported gravity flows in mud‐dominant environments. The experiments were carried out in an oscillatory water tunnel with a sediment bed of either 1% or 13% sand. Low and high energy regimes are differentiated based on a Stokes Reynolds number Re_Δ ≈ 500. In the low energy regime, the sand fraction influences flow dynamics primarily through ripple formation; no ripples form in the 1% sand experiments, whereas ripples form in the 13% experiments that increase turbulence and the wave boundary layer thickness, δ_m. In the high energy regime, small ripples form in both the 1% and 13% sand experiments and we observe high near‐bed suspended sediment concentrations. The influence of stratification on the boundary layer flow is characterized in terms of the gradient Richardson number Ri_g. The flow is weakly stratified inside the boundary layer for all runs and critically stratified at or above the top of the boundary layer. In the lower energy regime, the sand content reduces the relative influence of stratification in the boundary layer, shifting the elevation of critical stratification, L_B, from approximately 1.3δ_m to 2.5δ_m in the 1% and 13% experiments, respectively. In both sets of experiments L_B ≈ δ_m at the strongest wave energy, indicating a transition to strongly stratified dynamics.

中文翻译：

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沙在主要是泥泞海底的波浪边界层中的作用：对波浪支撑重力流的影响

我们进行了实验室实验，以研究含砂量对在泥浆为主的环境中波浪支撑重力流动力学的影响。实验是在带有1％或13％沙子的沉积床的振荡水隧道中进行的。低和高能量体制分化基于斯托克斯雷诺数重新_Δ 听，说：500。在低能量制度，沙分数影响流动主要是通过形成波纹动力学; 没有涟漪形成在1％砂实验，而波纹在13％实验形成增加紊流和波边界层厚度，δ_米。在高能态下，在1％和13％的沙实验中都会形成小的波纹，并且我们观察到了近床层悬浮沉积物的高浓度。用梯度理查森数Ri _g表征分层对边界层流动的影响。对于所有运行，流在边界层内部都是弱分层的，并且在边界层的顶部或上方是临界分层的。在较低的能量制度，砂含量减少分层的边界层的相对影响，移临界分层，标高大号_乙，从大约1.3 δ_米至2.5 δ_米分别在1％和13％的实验中。在这两组实验中的大号_乙 听，说：  δ_米处的最强波能，表明强烈分层动力学的过渡。