Dataset - Probability of suspension for nonuniform sediment

The probability of suspension for nonuniform sediment is an important parameter in mechanics of sediment transport, which is often used in the governing equations and boundary conditions of mathematical models. There were few theoretical research and experimental data on suspension probability, especially for nonuniform sediment. We investigates suspension probability for nonuniform sediment in turbulent flow. From the dynamic viewpoint, probability for sediment suspension was considered as one that the instantaneous lift force at the bottom is greater than the effective gravity of particles. Similarly, probability for sediment suspension is defined as one that the instantaneous upward velocity is greater than the settling velocity of particles. Assuming that the instantaneous longitudinal and vertical velocities near the bottom obey normal distribution, two probability expressions for any kth fraction of nonuniform suspended sediment are derived. An experimental method for the probabilities of sediment motion is proposed and used to flume experiments with uniform and nonuniform sediment. Then the formulas for probability of sediment suspension are obtained with coefficients determined by the experimental data on uniform suspended load. The calculated values from both proposed formulas agree well with the experimental data on nonuniform suspended load, showing high accuracy of the formulas. The datasets of suspension probability experiments for uniform and nonuniform sediment are uploaded as follows.非均匀泥沙（nonuniform sediment）的悬浮概率是泥沙运动力学（mechanics of sediment transport）中的重要参数，常被应用于数学模型（mathematical models）的控制方程（governing equations）与边界条件（boundary conditions）之中。目前针对悬浮概率的理论研究与实验数据较为匮乏，针对非均匀泥沙的相关研究更是不足。本文针对紊流（turbulent flow）中的非均匀泥沙悬浮概率展开研究。从动力学视角来看，泥沙悬浮概率可定义为床面瞬时升力（instantaneous lift force）大于颗粒有效重力（effective gravity）的概率；同理，泥沙悬浮概率也可定义为瞬时向上流速大于颗粒沉速（settling velocity）的概率。假设床面附近的瞬时纵向流速与垂向流速服从正态分布（normal distribution），本文推导得到了任意第k个粒组的非均匀悬沙的两类概率表达式。本文提出了一种泥沙运动概率的实验方法，并将其应用于均匀泥沙（uniform sediment）与非均匀泥沙的水槽实验（flume experiments）中。随后利用均匀悬移质（suspended load）的实验数据确定公式系数，得到了泥沙悬浮概率的计算公式。两类公式的计算结果与非均匀悬移质的实验数据吻合度较高，证明了公式具备较高的精度。本文上传了均匀泥沙与非均匀泥沙悬浮概率实验的相关数据集，具体如下。