Observations of particle capture on a cylindrical collector: Implications for particle accumulation and removal in aquatic systems
Observations of particle capture on a cylindrical collector: Implications for particle accumulation and removal in aquatic systems
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DOI：
10.4319/lo.2004.49.1.0076
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发表时间：
2004-01-01
影响因子：
4.5
通讯作者：
Pettersson, TJR
中科院分区：
文献类型：
--
作者：
Palmer, MR;Nepf, HM;Pettersson, TJR
圆柱形收集器捕获悬浮颗粒是许多水生过程中的重要机制，例如幼体沉降、悬浮摄食和植物过滤。在这些过程中，根据收集器直径，收集器雷诺数 (Re-c) 的范围远低于 1 到 1,000。不存在解析解来描述在这个范围的大部分范围内的捕获。捕获通常用效率 eta 来描述，定义为收集器上捕获的颗粒的上游跨度与收集器直径的比率。在这里，实验室实验用于测量单个圆筒的捕获效率，作为 Re-c 和颗粒比 R 的函数，R 是颗粒直径与收集器直径的比值。 Re-c 在 50 到 500 之间变化，并且使用三个 R 值：0.03、0.015 和 0.008。所选颗粒的比重为1.03。对于光滑圆柱体，捕获随着 Re-c 和 R 的增加而增加，但更强烈地依赖于 R。该结果表明，在流速和悬浮颗粒类型和尺寸固定的水生系统中，最小的收集器（具有最大 R 的收集器）将出现更高的捕获效率。此外，我们还研究了一个类似的实验，其中颗粒是通过分支结构收集的。我们表明，可以通过单圆柱效率来预测复合结构内单个圆柱分支的捕获。最后，当将粗糙度元素添加到收集器中时，捕获量会增加。
Capture of suspended particles by cylindrical collectors is an important mechanism in many aquatic processes, such as larval settlement, suspension feeding, and vegetative filtration. In these processes, the collector Reynolds number (Re-c), based on the collector diameter, ranges from well below 1 to 1,000. No analytical solutions exist to describe capture over most of this range. Capture is typically described by the efficiency, eta, defined as the ratio of the upstream span of particles that are captured on the collector to the collector diameter. Here, laboratory experiments are used to measure capture efficiency of a single cylinder as a function of Re-c and particle ratio, R, which is the ratio of particle diameter to collector diameter. Re-c is varied from 50 to 500 and three values of R are used: 0.03, 0.015, and 0.008. The selected particles have a specific gravity of 1.03. For smooth cylinders, capture increases with both Re-c and R but is more strongly dependent on R. This result indicates that, in aquatic systems, where flow velocity and suspended particle type and size are fixed, higher capture efficiency will occur on the smallest collectors (those with largest R). Furthermore, we examine a similar experiment in which particles are collected by branched structures. We show that capture to individual cylindrical branches within a compound structure can be predicted by single-cylinder efficiencies. Finally, capture was increased when roughness elements were added to the collectors.