Emergent vegetation has a significant impact on floating particle transport and diffusion in open channel flow. The random walk model of a Lagrangian approach has proven more than suitable to describe the rather unpredictable moving trajectory of particles within emergent vegetation. However, compared to the large computational costs of the Lagrangian model, which also requires more input data, a simplified model based on the Eulerian approach can be by far preferable and cost-effective for rapid first-order prediction of particle transport and diffusion within vegetated areas. In this study, we developed a one-dimensional advection-diffusion model to simulate particle transport processes within vegetated areas, and to explore the impacts of vegetation on particles transport, diffusion and removal. The model parameters, including the probability of a particle colliding with a stem, and the probability of it being temporarily trapped or permanently captured by a stem, as well as the mean retention time that govern the random walk model, are introduced to estimate the mean velocity, diffusion coefficient, removal rate of particles of Eulerian model, distinguishing from the standard advection and diffusion parameters. The validity of the parameters is verified through the stochastic model with a large number of realizations. The comparison between the dispersal kernel as well as the spatio-temporal distribution of floating particles predicted by Eulerian model and stochastic model is quite satisfactory and suggests that the Eulerian model we proposed is properly described.

中文翻译：

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新兴植被区域内漂浮粒子传输和扩散的欧拉模型

新兴植被对明渠流中漂浮颗粒的运输和扩散具有显着影响。拉格朗日方法的随机游走模型已被证明非常适合描述新兴植被内粒子的不可预测的移动轨迹。然而，与拉格朗日模型的大量计算成本相比，它也需要更多的输入数据，基于欧拉方法的简化模型对于植被内粒子传输和扩散的快速一阶预测迄今为止可能更可取且具有成本效益。领域。在这项研究中，我们开发了一个一维对流-扩散模型来模拟植被区域内的粒子传输过程，并探索植被对粒子传输、扩散和清除的影响。模型参数，包括粒子与茎碰撞的概率，它被茎暂时捕获或永久捕获的概率，以及控制随机游走模型的平均保留时间，被引入来估计平均速度，扩散系数，欧拉模型的颗粒去除率，区别于标准的平流和扩散参数。通过大量实现的随机模型验证了参数的有效性。欧拉模型和随机模型预测的扩散核以及漂浮粒子的时空分布的比较比较令人满意，表明我们提出的欧拉模型得到了正确的描述。并引入它被茎暂时捕获或永久捕获的概率，以及支配随机游走模型的平均保留时间，用于估计欧拉模型中粒子的平均速度、扩散系数、去除率，区别于标准对流和扩散参数。通过大量实现的随机模型验证了参数的有效性。欧拉模型和随机模型预测的扩散核以及漂浮粒子的时空分布的比较比较令人满意，表明我们提出的欧拉模型得到了正确的描述。并引入它被茎暂时捕获或永久捕获的概率，以及支配随机游走模型的平均保留时间，用于估计欧拉模型中粒子的平均速度、扩散系数、去除率，区别于标准对流和扩散参数。通过大量实现的随机模型验证了参数的有效性。欧拉模型和随机模型预测的扩散核以及漂浮粒子的时空分布的比较比较令人满意，表明我们提出的欧拉模型得到了正确的描述。扩散系数，欧拉模型的粒子去除率，区别于标准的平流扩散参数。通过大量实现的随机模型验证了参数的有效性。欧拉模型和随机模型预测的扩散核以及漂浮粒子的时空分布的比较比较令人满意，表明我们提出的欧拉模型得到了正确的描述。扩散系数，欧拉模型的粒子去除率，区别于标准的平流扩散参数。通过大量实现的随机模型验证了参数的有效性。欧拉模型和随机模型预测的扩散核以及漂浮粒子的时空分布的比较比较令人满意，表明我们提出的欧拉模型得到了正确的描述。