波浪及波流边界层泥沙起动规律

基于波浪边界层理论及单向流泥沙起动Shields曲线，推证出波浪泥沙起动Shields曲线；基于波流边界层理论，提出表述波流边界层动力特征的波流比因子X及非线性作用因子Y，并建立了Y与X的相关关系；在此基础之上，结合单向流及波浪泥沙起动Shields曲线，推证出波流共同作用下泥沙起动Shields曲线。结果表明:波浪泥沙起动Shields曲线在层流区与单向流光滑紊流区曲线保持一致，粗糙紊流区与单向流粗糙紊流区曲线保持一致，过渡区线型为折线，由层流区及粗糙紊流区曲线延长交汇获得；X及Y能够合理地表征波流边界层动力对比特征及非线性作用特征；波流泥沙起动Shields曲线介于波浪及单向流泥沙起动Shields曲线之间，随着波流比因子X的不同，依据非线性作用因子Y，自动在波浪及单向流泥沙起动Shields曲线之间非线性过渡。建立的波流泥沙起动Shields曲线与试验结果吻合较好，且能够概括单向流、波浪及波流等不同动力及细沙、粗沙等不同粒径的泥沙起动条件。

Incipient motion of sediment in wave and combined wave-current boundary layers

Based on the theory of wave boundary layers and the Shields curve, the criterion curve is developed for the incipient motion of sediment in a wave boundary layer in this study. Two factors (X and Y) are proposed to characterize the turbulent structure of wave-current boundary layers, and an empirical relationship between Y and X is established. Furthermore, a criterion curve is derived for the incipient motion of sediment in combined wave-current boundary layers. This is done through the consideration of individual criterion curves for waves only and currents only. Results show that the criterion curve for waves is consistent with the Shields curve for the laminar flow regime and for the rough turbulent flow regime, while for the laminar-rough turbulent flow transition regime, it follows a broken line distribution, which is the extension of the two flow regimes. The proposed two factors X and Y could reasonably describe the relative relation of waves and currents and the non-linear effect of wave-current interaction. The criterion curve for combined waves and currents transits between individual criterion curves for waves only and currents only, depending on the values of X and corresponding Y. The proposed criterion curve for combined waves and currents agrees well with the measured data and could be used for different hydrodynamic conditions (i.e., waves, currents, or their combined actions) and different particle sizes (i.e., from coarse to fine).