Sedimentation and sediment flow in settling tanks with inclined walls
Sedimentation and sediment flow in settling tanks with inclined walls
复制标题
斜壁沉淀池中的沉淀和泥沙流动
DOI：
10.1017/s0022112095002412
复制
发表时间：
1995
影响因子：
3.7
通讯作者：
A. Acrivos
中科院分区：
文献类型：
--
作者：
B. Kapoor;A. Acrivos
本文从理论和实验两方面研究了由于球形颗粒的稳定沉降而在倾斜平板上形成的沉淀层的流动。理论分析基于Nir和Acrivos(1990)提出的模型，修正后的模型考虑了由于剪应力梯度引起的剪切诱导扩散以及由于颗粒尺寸有限而导致的沿壁面的滑移速度。所得到的偏微分方程组在前缘附近和下游都可以得到相似类型的解，使用有限差分格式进行了数值求解，从而得到了整个板块沿线的颗粒浓度和速度分布以及局部沉积物层厚度的理论预测。此外，发展了一种新的基于激光多普勒测速的实验技术，并用于测量高浓度泥沙层中的颗粒速度分布以及相应的滑移系数，该系数将滑移速度与壁面附近的速度梯度联系起来。用视频成像的方法测量了沉积层的厚度分布。结果表明，对于颗粒速度分布和局部泥沙层厚度的实验结果与相应的理论预测非常吻合，特别是考虑到后者没有使用任何可调参数。
The flow of a sediment layer that forms on an inclined plate as a consequence of the steady sedimentation of spherical particles was investigated theoretically as well as experimentally. The theoretical analysis was based on the model proposed by Nir & Acrivos (1990), modified to include shear-induced diffusion due to gradients in the shear stress as well as a slip velocity along the wall due to the finite size of the particles. The resulting set of partial differential equations, which is amenable to a similarity-type solution both near the leading edge as well as far downstream, was solved numerically using a finite difference scheme thereby yielding theoretical predictions for the particle concentration and velocity profiles, plus the local sediment layer thickness, all along the plate. In addition, a new experimental technique based on laser Doppler anemometry was developed and was used to measure the particle velocity profiles in the highly concentrated sediment layer as well as the corresponding slip coefficient which relates the slip velocity to the velocity gradient adjacent to a wall. The thickness profile of the sediment layer was also measured experimentally by means of video imaging. It was found that the experimental results thus obtained for the particle velocity profile and for the local sediment layer thickness were in very good agreement with the corresponding theoretical predictions especially considering that the latter did not make use of any adjustable parameters.