支持这项研究是由授予约旦第纳尔的国家科学基金会（OCE - 0623475），SPC（OCE - 0623534和0727544），并JHC（OCE - 0727587和奥西- 0623508），由海军研究办公室授予JHC（ N000140810654）。 KK是德文郡基金会提供资金，由伍兹霍尔海洋研究所的博士后学者计划的支持。

<ol><li>要开始此过程中，我们将确保所有SCUVA组件电量充足的电池，录音磁带（高清晰度或高清摄像机），和功能正常。根据流量来衡量，选择1,2摄像头的分辨率和帧速率产生数字粒子图像测速（DPIV）最好的结果。 </li><li>准备使用激光和摄像机防护罩，用干净的毛巾清洁的O型环槽和O形圈或擦拭。传播制造商提供均匀O型环，O型圈润滑脂和更换住房槽。此外，清洁激光和摄像机外壳孔的相机房屋镜头，以防止激光板材变形和标志。 </li><li>检查O型圈密封，放置在一个充满水的浴缸都空外壳。将需要淹没他们置于顶部的外壳，因为外壳的浮空时加权对象。 5至10分钟后，取出从浴缸和毛巾擦干吨的外壳他在外面。检查是否有任何的外壳内的水分。也可以考虑使用压力测试期间一次性的，纸张的湿度带的外壳是否有水分测试后。 </li><li>后外壳通过压力测试，SCUVA组件外壳内。 </li><li>附加高强度放电（HID）灯豆荚摄像机外壳。确保灯都以这样一种方式，他们照亮的面积正前方的摄像头和运营商为导向，不干扰处理及相机控制操作与维护握。 </li><li>在光线较暗的环境，确保正确对齐相安装在激光住房光学镜头，激光束。正确对齐，激光/镜头组合将创建一个垂直的光表是面向垂直相机住房。为了安全起见，用一张纸对温度敏感的板材，以确定激光片方向。 </李&gt; <li>使用SCUVA附件和僵化，伸缩臂，激光住房和摄像机外壳连接到对方。确保外壳牢固地附着的外壳相互尊重，不能旋转。至关重要的是激光片仍然面向垂直相机的整个测量领域。 </li><li>由于SCUVA目前的能力，测量潜水只能在光线不足的场所或夜间进行，以防止激光片自然光的干涉。因此，我们建议入水前等待，直到黄昏或更高版本。 </li><li>入水前，打开相机外壳上。摄像机外壳有一个内置的电子湿度传感器提供水分的情况下摄像机外壳的视觉警告（LED灯闪烁）。仅当相机外壳上的传感器。 </li><li>在水中浸泡SCUVA和重视自己使用的仪器一条线。一旦连接到仪器，释放SCUVA，以确定该设备的浮力特性。根据浮力的特点，将浮力泡沫或铅块一个或两个外壳，以确保中性浮力，防止用水器具的旋转。 </li><li>下一步，交换机上的激光和保持仪器固定。激光定位，从潜水员使用的伸缩臂足够远，以尽量减少测量潜水员诱导流动。任何测量目标附近的潜水员诱导流动引入错误和不供后续分析使用。相机变焦调整，直到实地查看帧的目标和周围流体。 </li><li>虽然保持固定的器具，重点激光负债表上的摄像头，直到颗粒出现急剧和重点。一旦激光片平面的重点是，相机切换到手动对焦模式。这将防止相机领域中出现的任何对象的重新定位查看在测量过程中，导致在激光片模糊的颗粒。 </li><li>要校准SCUVA，地方与激光负债表中已知尺寸的摄像头的视野内的一个对象。几秒钟的记录。潜水后，图像将被从这个视频序列中提取，以确定校准常数转换厘米像素为单位的视场大小。如果操作员随时调整视场大小被重新定位，伸缩臂或在不断变化的潜水相机变焦，步骤12和13将需要重复。 </li><li>开始降工作深度潜水。发现目标后，对环境的散流属性需要确定。如果存在，电流的方向，将决定设备和潜水员在测量过程中的目标定位相对。周围目标的散装流的方向可以推断通过观察气泡从潜水员呼出，并指出它们的横向运动。在除泡沫，少量的荧光染料（即，荧光素）可以释放，以确定当前的方向。由于潜水员产生的流量可以DPIV测量误差的来源，潜水员不应位于上游的目标。此外，激光片应定位电流方向平行，以最大限度地提高粒子的激光片内的停留时间，从而最大限度地减少DPIV错误。但是，如果没有当前或散流目前，潜水员和SCUVA定位相对目标是不受限制的。 </li><li>位置SCUVA，照亮并记录周围流体运动目标。如果试图记录流，围绕一个移动的目标首先预测的目标位置，然后位置SCUVA预测的位置，而余下的一动不动。作为目标，通过移动摄像机的视野，开始录制。如果目标是一动不动，在摄像头帧的目标和周围流体＃x2019;实地查看，并开始录制，而余下的一动不动。经营者应避免在录制视频的旋转和平面运动，因为这些错误的DPIV结果的议案结果。因此，测量期间收集的旋转和平面潜水员议案将不被用于进一步的数据进行分析。 </li><li>一旦视频采集完成后，关闭SCUVA所有元件和激光手臂恢复其缩回位置。从水中取出SCUVA和从手臂分离相机和激光外壳。冲洗或在淡水中浸泡，然后干燥，以防止生锈的设备仪器。一旦干燥的外壳，从外壳移除组件，以及充电和更换电池如果需要另一个潜水。 </li><li>摄像头连接到计算机，并使用了高清视频软件包（即Adobe Premiere Pro或iMovie中）从高清磁带中提取的视频。视频提取后，确定范围视频转换成一系列图像DPIV分析。确保像素长宽比和提取的图像大小相匹配的高清视频设置。 </li><li>这些图像导入到一个DPIV处理程序（即戴维斯或MatPIV）。经过校准常数和图像采集参数，这是从DPIV软件包提示正确的选择，速度场，可以生成从连续的粒子图像。额外的后处理步骤，根据测量的质量和类型，也可应用。 </li></ol>代表性的成果: 当协议是正确的，目标周围的粒子图像锐利，容易分辨。使用SCUVA的摄像头（图1A）和一个DPIV处理软件包，目标周围流（图1B）速度场就地捕获粒子领域将被揭示。向量中的velociTY领域，表明当地流速的大小和方向。如果有足够的视频是收集到的图像提供的时间序列，速度场的时间序列也可确定。 <img src="/files/ftp_upload/2615/2615fig1.jpg" alt="图1"/> 图1 在原位颗粒领域（一）围绕奥里利亚labiata。相应的速度场（B）与指示流动方向和大小的黄色向量。 <img src="/files/ftp_upload/2615/2615fig2.jpg" alt="图2"/> 图2 原位颗粒周围Mastigias SP领域和Solmissus SP（A和B，分别）。 A中的红色箭头表示高反射率的地区，从而导致图像的饱和度，使其难以区分粒子和目标。在B的红色箭头表示裸奔，结果，当流量地区没有足够高的频率采样。

<ol>
	<li>Adrian, R. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Particle-imaging+techniques+for+experimental+fluid+mechanics.">Particle-imaging techniques for experimental fluid mechanics.</a> Ann. Rev. Fluid Mech. 23, 261-304 (1991).</li><li>Willert, C. E., Gharib, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Digital+particle+image+velocimetry.">Digital particle image velocimetry.</a> Exp. Fluids. 10, 181-193 (1991).</li><li>Raffel, M., Willert, C., Wereley, S., Kompenhans, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Particle Image Velocimetry: A Practical Guide. , (2007).</li><li>Agrawal, Y. C., Pottsmith, H. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser+diffraction+particle+sizing+in+STRESS.">Laser diffraction particle sizing in STRESS.</a> Cont. Shelf Res. 14, 1101-1121 (1994).</li><li>Katz, J., Donaghay, P. L., Zhang, J., King, S., Russell, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Submersible+holocamera+for+detection+of+particle+characteristics+and+motions+in+the+ocean.">Submersible holocamera for detection of particle characteristics and motions in the ocean.</a> Deep Sea Res. 46, 1455-1481 (1999).</li><li>Katija, K., Dabiri, J. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+situ+field+measurements+of+aquatic+animal-fluid+interactions+using+a+self-contained+underwater+velocimetry+apparatus+(SCUVA).">In situ field measurements of aquatic animal-fluid interactions using a self-contained underwater velocimetry apparatus (SCUVA).</a> Limnol. Oceanogr.-Meth. 6, 162-171 (2008).</li></ol>

没有利益冲突的声明。

在该领域的潜在制约因素是粒子流，这是必要的，以实现数字粒子图像测速（DPIV）的需要。在沿海水域，悬浮颗粒物展品尺寸上的直径10微米和0.002，每毫米3 10之间的浓度的顺序4。更多的研究使用粒子检测确认存在足够的种子颗粒在海水执行DPIV潜水holocamera。 5在公海和沿海海洋潜水，我们发现，粒子密度和大小不进行原位 DPIV的约束。 除了粒子密度和大小，另一个值得关注的相关DPIV测量颗粒物浓度的同质性。 定性，如果审讯窗口内的一个地区的颗粒物浓度大于另一个，速度的大小由D生成PIV技术分析，将偏重的地区，具有较高的粒子浓度。因此，SCUVA测量必须进行颗粒物浓度的变化是最小化。我们发现thatcle浓度在颗粒物浓度的相对恒定的，在潜水员在水柱的中间暂停潜水期间相对恒定的。然而，在海底环境中的粒子领域不均匀由于附近海底的环境或潜​​水员诱导流动的颗粒再悬浮的潜力。必须小心，以尽量减少在底栖环境的测量粒子的破坏。作者的知识，还没有正式的不均匀颗粒浓度场产生的错误分析无论是实验室或野外条件下进行，并应进一步考虑在一个单独的出版物的主题。 有几种不同的问题，应考虑在编制和在使用该协议进行现场试验。在录制过程中，操作指示，保持静止，不要所有飞机和旋转运动。这个要求很简单，在理论上却难以在实践中，这些测量需要先进的潜水技能，得以圆满完成。出平面和旋转运动的错误DPIV数据运算符的结果。然而，在平面议案可以通过使用内部软件纠正。 六是建议几个潜水浮力控制前使用SCUVA，最大限度地提高了测量效率的经营实践。 除了浮力的考虑，经营者应当知道目标的流动方向。流，旅游的平面激光片不会产生可靠的DPIV结果，和经营者应东方SCUVA捕捉到这些流动的最有效。此外，潜水员到目标的相对位置必须selecteð，以尽量减少诱导潜水员在流量测量。潜水员诱导流引入了错误的目标流量，不应作进一步的分析和测量，包括潜水员影响。 在事件目标表面具有高反射率，流体周边地区的目标将受到强烈的照明，使其难以分辨周围的流体（红色箭头，图2A表示地区）附近的单个粒子。可以被添加到过滤器或偏光片的激光或摄像机防护罩，以减少摄像传感器所捕获的激光强度。如果这是不可能的的，由于后勤方面的限制和有限的接入设备，使用内部软件的图像后处理，可以提供足够的校正，从图像中减去靠近目标的像素强度升高。另一个需要考虑的影响DPIV数据的质量是粒子条纹是否存在。如果粒子领域有裸奔的区域（红色箭头，图2B表示），摄像头录制的帧速率太低，解决这些高的速度。通过增加帧速率，可以减少粒子裸奔。然而，这个结果在减少光深远的摄像传感器，使得粒子现场看调光。如果摄像头能够手动设置光圈设置，增加光圈设置，以防止调光的粒子场。确定最佳的设备设置，可能需要多个成功的数据收集前SCUVA潜水。

quantitatively measuring in situ flows using a self-contained underwater velocimetry apparatus (scuva)

海洋学，生态学，生物学，流体力学等不同领域的研究提供实证数据的能力，直接测量流体环境中速度场是必要的。实地测量引入实际的挑战，如环境条件下，动物的空房情况，并现场兼容测量技术的需要。为了避免这些挑战，科学家们通常使用受控的实验室环境，研究动物流体相互作用。但是，它是合理的问题，是否可以推断从实验室测量自然的行为（即，在外地发生）。因此， 在原位定量流量测量需要准确地描述动物在自然环境中游泳。 我们设计了一个自成体系，独立于任何表面的连接的便携设备，操作，并能提供定量测量流场surrounding一个动物。一个自成体系的水下测速装置（SCUVA），这种仪器，可以由一个单潜水员在深度40米由于增加了复杂性的野外条件下，额外的考虑和准备的固有的需要相比，实验室测量。这些考虑因素包括，但不仅限于，运营商的议案，预测游泳的目标，现有的自然悬浮微粒，和利益的流动相对SCUVA方向的位置。以下协议的目的是，以解决这些共同的领域的挑战，并最大限度地提高测量成功。

Watch this Scientific Journal Video about Quantitatively Measuring In situ Flows using a Self-Contained Underwater Velocimetry Apparatus SCUVA at JoVE.com

Quantitatively Measuring In situ Flows using a Self-Contained Underwater Velocimetry Apparatus SCUVA

此协议提供了有关如何使用一个自包含水下测速仪（SCUVA），这是量化原位动物产生的流动设计的说明。此外，这个协议解决了野战条件所带来的挑战，包括运营商的议案，预测动物的位置，方向和SCUVA。

定量测量原位流动，使用一个自包含的水下测速仪（SCUVA）

The ability to directly measure velocity fields in a fluid environment is necessary to provide empirical data for studies in fields as diverse as ...

quantitatively-measuring-situ-flows-using-self-contained-underwater

Nanyang Technological University

Research

JoVE Journal

Bioengineering

Quantitatively Measuring In situ Flows using a Self-Contained Underwater Velocimetry Apparatus (SCUVA)

12.9K 次观看.  Woods Hole Oceanographic Institution. 此协议提供了有关如何使用一个自包含水下测速仪（SCUVA），这是量化原位动物产生的流动设计的说明。此外，这个协议解决了野战条件所带来的挑战，包括运营商的议案，预测动物的位置，方向和SCUVA。

视频: Quantitatively Measuring In situ Flows using a Self-Contained Underwater Velocimetry Apparatus SCUVA

Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we present the fabrication protocol for a multilayered SAW acoustic counterflow device. The device is fabricated starting from a lithium niobate (LN) substrate onto which two interdigital transducers (IDTs) and appropriate markers are patterned. A polydimethylsiloxane (PDMS) channel cast on an SU8 master mold is finally bonded on the patterned substrate. Following the fabrication procedure, we show the techniques that allow the characterization and operation of the acoustic counterflow device in order to pump fluids through the PDMS channel grid. We finally present the procedure to visualize liquid flow in the channels. The protocol is used to show on-chip fluid pumping under different flow regimes such as laminar flow and more complicated dynamics characterized by vortices and particle accumulation domains.

In this video we first describe fabrication and operation procedures of a surface acoustic wave (SAW) acoustic counterflow device. We then demonstrate an experimental setup that allows for both qualitative flow visualization and quantitative analysis of complex flows within the SAW pumping device.

制造，操作和表面声波驱动声逆流微流体流动可视化

Surface acoustic waves (SAWs) can be used to drive liquids in portable microfluidic chips via the acoustic counterflow phenomenon. In this video we ...

科研

工程学

VacuSIP, an Improved InEx Method for In Situ Measurement of Particulate and Dissolved Compounds Processed by Active Suspension Feeders

Benthic suspension feeders play essential roles in the functioning of marine ecosystems. By filtering large volumes of water, removing plankton and detritus, and excreting particulate and dissolved compounds, they serve as important agents for benthic-pelagic coupling. Accurately measuring the compounds removed and excreted by suspension feeders (such as sponges, ascidians, polychaetes, bivalves) is crucial for the study of their physiology, metabolism, and feeding ecology, and is fundamental to determine the ecological relevance of the nutrient fluxes mediated by these organisms. However, the assessment of the rate by which suspension feeders process particulate and dissolved compounds in nature is restricted by the limitations of the currently available methodologies. Our goal was to develop a simple, reliable, and non-intrusive method that would allow clean and controlled water sampling from a specific point, such as the excurrent aperture of benthic suspension feeders, in situ. Our method allows simultaneous sampling of inhaled and exhaled water of the studied organism by using minute tubes installed on a custom-built manipulator device and carefully positioned inside the exhalant orifice of the sampled organism. Piercing a septum on the collecting vessel with a syringe needle attached to the distal end of each tube allows the external pressure to slowly force the sampled water into the vessel through the sampling tube. The slow and controlled sampling rate allows integrating the inherent patchiness in the water while ensuring contamination free sampling. We provide recommendations for the most suitable filtering devices, collection vessel, and storing procedures for the analyses of different particulate and dissolved compounds. The VacuSIP system offers a reliable method for the quantification of undisturbed suspension feeder metabolism in natural conditions that is cheap and easy to learn and apply to assess the physiology and functional role of filter feeders in different ecosystems.

VacuSIP, an Improved InEx Method for In Situ Measurement of Particulate and Dissolved Compounds Processed by Active Suspension Feeders

We introduce the VacuSIP, a simple, non-intrusive, and reliable method for clean and accurate point sampling of water. The system was developed and evaluated for the simultaneous collection of the water inhaled and exhaled by benthic suspension feeders in situ, to cleanly measure removal and excretion of particulate and dissolved compounds.

VacuSIP，对改进的方法INEX<em&gt;原位</em&gt;颗粒物与测量溶解的化合物加工后主动悬挂给料机

Benthic suspension feeders play essential roles in the functioning of marine ecosystems. By filtering large volumes of water, removing plankton and ...

环境科学

Image-based Lagrangian Particle Tracking in Bed-load Experiments

Image analysis has been increasingly used for the measurement of river flows due to its capabilities to furnish detailed quantitative depictions at a relatively low cost. This manuscript describes an application of particle tracking velocimetry (PTV) to a bed-load experiment with lightweight sediment. The key characteristics of the investigated sediment transport conditions were the presence of a covered flow and of a fixed rough bed above which particles were released in limited number at the flume inlet. Under the applied flow conditions, the motion of the individual bed-load particles was intermittent, with alternating movement and stillness terms. The flow pattern was preliminarily characterized by acoustic measurements of vertical profiles of the stream-wise velocity. During process visualization, a large field of view was obtained using two action-cameras placed at different locations along the flume. The experimental protocol is described in terms of channel calibration, experiment realization, image pre-processing, automatic particle tracking, and post-processing of particle track data from the two cameras. The presented proof-of-concept results include probability distributions of the particle hop length and duration. The achievements of this work are compared to those of existing literature to demonstrate the validity of the protocol.

The manuscript presents a protocol for the conduction of bed-load sediment transport experiments where the moving particles are tracked by image analysis. The experimental facility, the procedures for run realization and data processing, and finally some proof-of-concept results are presented here.

基于图像的拉格朗日粒子跟踪在床载荷实验

Image analysis has been increasingly used for the measurement of river flows due to its capabilities to furnish detailed quantitative depictions at a ...

Continuous Instream Monitoring of Nutrients and Sediment in Agricultural Watersheds

Pollutant concentrations and loads in watersheds vary considerably with time and space. Accurate and timely information on the magnitude of pollutants in water resources is a prerequisite for understanding the drivers of the pollutant loads and for making informed water resource management decisions. The commonly used &#34;grab sampling&#34; method provides the concentrations of pollutants at the time of sampling (i.e., a snapshot concentration) and may under- or overpredict the pollutant concentrations and loads. Continuous monitoring of nutrients and sediment has recently received more attention due to advances in computing, sensing technology, and storage devices. This protocol demonstrates the use of sensors, sondes, and instrumentation to continuously monitor in situ nitrate, ammonium, turbidity, pH, conductivity, temperature, and dissolved oxygen (DO) and to calculate the loads from two streams (ditches) in two agricultural watersheds. With the proper calibration, maintenance, and operation of sensors and sondes, good water quality data can be obtained by overcoming challenging conditions such as fouling and debris buildup. The method can also be used in watersheds of various sizes and characterized by agricultural, forested, and/or urban land.

With the advancement of technology and the rise in end-user expectations, the need and use of higher temporal resolution data for pollutant load estimation has increased. This protocol describes a method for continuous in situ water quality monitoring to obtain higher temporal resolution data for informed water resource management decisions.

农业流域营养盐和泥沙的连续河道监测

Pollutant concentrations and loads in watersheds vary considerably with time and space. Accurate and timely information on the magnitude of pollutants in ...

Visualizing Hyporheic Flow Through Bedforms Using Dye Experiments and Simulation

Advective exchange between the pore space of sediments and the overlying water column, called hyporheic exchange in fluvial environments, drives solute transport in rivers and many important biogeochemical processes. To improve understanding of these processes through visual demonstration, we created a hyporheic flow simulation in the multi-agent computer modeling platform NetLogo. The simulation shows virtual tracer flowing through a streambed covered with two-dimensional bedforms. Sediment, flow, and bedform characteristics are used as input variables for the model. We illustrate how these simulations match experimental observations from laboratory flume experiments based on measured input parameters. Dye is injected into the flume sediments to visualize the porewater flow. For comparison virtual tracer particles are placed at the same locations in the simulation. This coupled simulation and lab experiment has been used successfully in undergraduate and graduate laboratories to directly visualize river-porewater interactions and show how physically-based flow simulations can reproduce environmental phenomena. Students took photographs of the bed through the transparent flume walls and compared them to shapes of the dye at the same times in the simulation. This resulted in very similar trends, which allowed the students to better understand both the flow patterns and the mathematical model. The simulations also allow the user to quickly visualize the impact of each input parameter by running multiple simulations. This process can also be used in research applications to illustrate basic processes, relate interfacial fluxes and porewater transport, and support quantitative process-based modeling.

This manuscript describes how to create regular bedforms in a flume, visualize flow through the bedforms, and use computer simulations to simulate the hyporheic flow. The computer simulations compare well with the experimental observations. This coupled simulation and experiment is well-suited for both research and educational purposes.

可视化潜流流通过底形用染料试验及仿真

Advective exchange between the pore space of sediments and the overlying water column, called hyporheic exchange in fluvial environments, drives solute ...

Design and Use of an Apparatus for Quantifying Bivalve Suspension Feeding at Sea

As shellfish aquaculture moves from coastal embayments and estuaries to offshore locations, the need to quantify ecosystem interactions of farmed bivalves (i.e., mussels, oysters, and clams) presents new challenges. Quantitative data on the feeding behavior of suspension-feeding mollusks is necessary to determine important ecosystem interactions of offshore shellfish farms, including their carrying capacity, the competition with the zooplankton community, the availability of trophic resources at different depths, and the deposition to the benthos. The biodeposition method is used to quantify feeding variables in suspension-feeding bivalves in a natural setting and represents a more realistic proxy than laboratory experiments. This method, however, relies upon a stable platform to satisfy the requirements that water flow rates supplied to the shellfish remain constant and the bivalves are undisturbed. A flow-through device and process for using the biodeposition method to quantify the feeding of bivalve mollusks were modified from a land-based format for shipboard use by building a two-dimensional gimbal table around the device. Planimeter data reveal a minimal pitch and yaw of the chambers containing the test shellfish despite boat motion, the flow rates within the chambers remain constant, and operators are able to collect the biodeposits (feces and pseudofeces) with sufficient consistency to obtain accurate measurements of the bivalve clearance, filtration, selection, ingestion, rejection, and absorption at offshore shellfish aquaculture sites.

A flow-through device for using the biodeposition method to quantify filtration and feeding behavior of bivalve mollusks was modified for shipboard use. A two-dimensional gimbal table built around the device isolates the apparatus from boat motion, thereby allowing the accurate quantification of bivalve filtration variables at offshore shellfish aquaculture sites.

海上双壳贝类悬浮饲料定量装置的设计与应用

As shellfish aquaculture moves from coastal embayments and estuaries to offshore locations, the need to quantify ecosystem interactions of farmed bivalves ...

Visualization of Flow Field Around a Vibrating Pipeline Within an Equilibrium Scour Hole

An experimental method is presented in this paper to facilitate visualization of the detailed flow fields and determination of the near-boundary shear and normal stresses within an equilibrium scour hole induced by a vibrating pipeline. This method involves the implementation of a pipeline vibration system in a straight flume, a time-resolved particle image velocimetry (PIV) system for pipeline displacement tracking and flow fields measurements. The displacement time-series of the vibrating pipeline are obtained by using the cross-correlation algorithms. The steps for processing raw particle laden images obtained by using the time-resolved PIV are described. The detailed instantaneous flow fields around the vibrating pipeline at different vibrating phases are calculated by using a multiple-time-interval cross-correlation algorithm to avoid displacement bias error in the flow regions with a large velocity gradient. By applying the wavelet transform technique, the captured images that have the same vibrating phase are accurately cataloged before the phase-averaged velocity fields are obtained. The key advantages of the flow measurement technique described in this paper are that it has a very high temporal and spatial resolution and can be simultaneously used to obtain the pipeline dynamics, flow fields, and near-boundary flow stresses. By using this technique, more in-depth studies of the 2-dimensional flow field in a complex environment, such as that around a vibrating pipeline, can be conducted to better understand the associated sophisticated scour mechanism.

The goal of the protocol is to enable visualization of the detailed flow fields and determination of the near-boundary shear and normal stresses within an equilibrium scour hole induced by a vibrating pipeline.

平衡闪烁孔内振动管道周围流动场的可视化

An experimental method is presented in this paper to facilitate visualization of the detailed flow fields and determination of the near-boundary shear and ...

Measurements of Waves in a Wind-wave Tank Under Steady and Time-varying Wind Forcing

This manuscript describes an experimental procedure that allows obtaining diverse quantitative information on temporal and spatial evolution of water waves excited by time-dependent and steady wind forcing. Capacitance-type wave gauge and Laser Slope Gauge (LSG) are used to measure instantaneous water surface elevation and two components of the instantaneous surface slope at a number of locations along the test section of a wind-wave facility. The computer-controlled blower provides airflow over the water in the tank whose rate can vary in time. In the present experiments, the wind speed in the test section initially increases quickly from rest to the set value. It is then kept constant for the prescribed duration; finally, the airflow is shut down. At the beginning of each experimental run, the water surface is calm and there is no wind. Operation of the blower is initiated simultaneously with the acquisition of data provided by all sensors by a computer; data acquisition continues until the waves in the tank fully decay. Multiple independent runs performed under identical forcing conditions allow determining statistically reliable ensemble-averaged characteristic parameters that quantitatively describe wind-waves&#39; variation in time for the initial development stage as a function of fetch. The procedure also allows characterizing the spatial evolution of the wave field under steady wind forcing, as well as decay of waves in time, once the wind is shut down, as a function of fetch.

This manuscript describes a fully computer-controlled procedure that allows obtaining reliable statistical parameters from experiments of water waves excited by steady and unsteady wind forcing in a small-scale facility.

稳定时变风强迫下风浪罐中波浪的测量

This manuscript describes an experimental procedure that allows obtaining diverse quantitative information on temporal and spatial evolution of water ...

Simultaneous Measurement of Turbulence and Particle Kinematics Using Flow Imaging Techniques

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine micro-organisms, and/or sediments in the ocean, or fluidized bed reactors and combustion processes in engineered systems. In order to study the effect of turbulence on the kinematics of particles in such flows, simultaneous measurements of both the flow and particle kinematics are required. Non-intrusive, optical flow measurement techniques for measuring turbulence, or for tracking particles, exist but measuring both simultaneously can be challenging due to interference between the techniques. The method presented herein provides a low cost and relatively simple method to make simultaneous measurements of the flow and particle kinematics. A cross section of the flow is measured using a particle image velocimetry (PIV) technique, which provides two components of velocity in the measurement plane. This technique utilizes a pulsed-laser for illumination of the seeded flow field that is imaged by a digital camera. The particle kinematics are simultaneously imaged using a light emitting diode (LED) line light that illuminates a planar cross section of the flow that overlaps with the PIV field-of-view (FOV). The line light is of low enough power that it does not affect the PIV measurements, but powerful enough to illuminate the larger particles of interest imaged using the high-speed camera. High-speed images that contain the laser pulses from the PIV technique are easily filtered by examining the summed intensity level of each high-speed image. By making the frame rate of the high-speed camera incommensurate with that of the PIV camera frame rate, the number of contaminated frames in the high-speed time series can be minimized. The technique is suitable for mean flows that are predominantly two-dimensional, contain particles that are at least 5 times the mean diameter of the PIV seeding tracers, and are low in concentration.

The technique described herein offers a low cost and relatively simple method to simultaneously measure particle kinematics and turbulence in flows with low particle concentrations. The turbulence is measured using particle image velocimetry (PIV), and particle kinematics are calculated from images obtained with a high-speed camera in an overlapping field-of-view.

流成像技术同时测量湍流和粒子运动学

Numerous problems in scientific and engineering fields involve understanding the kinematics of particles in turbulent flows, such as contaminants, marine ...

Measuring Turbulent Flows

Source: Ricardo Mejia-Alvarez and Hussam Hikmat Jabbar, Department of Mechanical Engineering, Michigan State University, East Lansing, MI
Turbulent flows exhibit very high frequency fluctuations that require instruments with high time-resolution for their appropriate characterization. Hot-wire anemometers have a short enough time-response to fulfill this requirement. The purpose of this experiment is to demonstrate the use of hot-wire anemometry to characterize a turbulent jet.
In this experiment, a previously calibrated hot-wire probe will be used to obtain velocity measurements at different positions within the jet. Finally, we will demonstrate a basic statistical analysis of the data to characterize the turbulent field.

Measuring Turbulent Flows Using Hot-Wire Anemometers

测量紊流

Source: Ricardo Mejia-Alvarez and Hussam Hikmat Jabbar, Department of Mechanical Engineering, Michigan State University, East Lansing, MI
Turbulent flows ...