This material is based upon work supported by National Science Foundation grants EAR-0810270, EAR-1215898, and EAR-1344280, as well as an&#160;NSF Graduate Research Fellowship.

1.仿真软件<ol><li>使用本节所述的软件。 <ol><li>下载并安装免费/开源的多智能体建模语言和仿真平台，的NetLogo（可用<a href="http://ccl.northwestern.edu/netlogo/">：http://ccl.northwestern.edu/netlogo/，</a>版本5.1或更高版本）。 注：该软件是免费提供的成本和运行在所有主要操作系统（Windows / Mac上/ Linux的）。 </li><li>下载伴随该实验室过程中的两个具体的仿真脚本文件（mousedrop.nlogo和interface.nlogo）。 (Available: <a href="http://modelingcommons.org/browse/one_model/4259">http://modelingcommons.org/browse/one_model/4259</a> and <a href="http://modelingcommons.org/browse/one_model/4258">http://modelingcommons.org/browse/one_model/4258</a> ) 注意：一旦仿真平台的安装和这些文件下载完毕后，双击这些文件会自动打开牛逼他模拟了起来，准备运行。 </li></ol></li></ol> 2.水槽演示<ol><li>建立实验室水槽，以便所有的参数（ 表1）落入mousedrop仿真参数范围限制内。 注意：约束可以在mousedrop进行调整，如果通过编辑滑块所需的物理系统。 <ol><li>倒入一层沙子约15-25厘米到水槽。测量和记录下列标准方法32,33的水力传导率沙和孔隙率。 </li><li>随着水约20-30厘米填写的水槽。 </li><li>启动水槽和提高流速的水平，是足够快，以移动砂粒，从而创造底形。 注：流速可以进一​​步调节到缩小底形特征与实践。底形尺寸的流速，水的深度和砂性能的结果。 </li><li>允许底形发展FO- [R 12-24小时，形成天然的沙丘/波纹形态。为了加快这一进程，人工塑造定期的沙丘，然后允许输沙为4-12小时。另外，手动形成规则的三角形沙丘。 注意：常规三角沙丘将产生定期潜流交换模式，但将不会显示尽可能多的复杂性，因为天然沙丘/波纹底形。 </li><li>一旦所需的河床得以实现，减少水流量，直到底泥运输放缓，底形特征不再变化。 <ol><li>直观地观察沉积物颗粒，包括床上运动，减少流量，直至运动停止。 注意：这将保留在床的形态为实验的持续时间。 </li><li>为了证实慢，情景运动不发生，标记或照片底形的位置，然后观察在以后的时间。 注意：唯一重要的是底形不要过度实验的时间帧显著移动，所以，可提供足够的观测时间，以确认底形是稳定的。 </li></ol></li><li>调整水槽斜率和/或水深度，以实现下的简化的流率均匀流动。 <ol><li>通过设备控制通道坡度构造成水槽，通常是电动千斤顶或手摇。通过添加或从水槽中除去水调整水的深度。 注：在实验装置用在这里，在整个水槽上安装在下游端的枢轴，且斜率由机动千斤顶在上游端设置的。 </li><li>当泵在运行中，选择标有垂直于水槽的底部线两纵位置。在这些位置，用尺子来测量沿着这些垂直线的距离，水的表面与水槽的底部之间。 注意：根据所述水槽设置，水槽的底部可以用作比水槽的底部更好的倾斜基准线。选择LARGER纵向距离将产生更高的精度。 </li><li>调整水槽和/或水深度和重新测量的斜率，直到垂直距离的测量是相同的，达到均匀流动。测量沿两个纵向位置之间的水槽的底部的倾斜水平距离。 </li></ol></li><li>停泵并等待水停止移动;这将提供一个水平面上。重新测量水槽的顶部和水面之间的距离，在每个纵向位置。 注意：通道斜率等于这些测量之间的差，通过它们之间的倾斜的水平距离除以。 </li><li>重新启动水泵。 </li><li>选择一个测试段，这应该是接近其中沙丘已经形成的规则图案水槽的中间或下游端的一个位置。确保此部分包括至少一个完整的底形。 </li><li>测量并记录平均输沙深度（D）的日与任何手工测量色器件Ë试验段（透明的统治者是理想的）。为简单起见，用一个波峰和波谷的平均距离水槽底部。 </li><li>测量并记录平均底形高度在试验部分中，限定为在用尺子槽沉积物深度在波峰和沉积物深度之间的差异。测量几个底形，以获得平均的良好估计。 </li><li>再次使用标尺，测量并记录平均水深度（d）在试验部分中，定义为从水表面到砂床的平均距离。同样，使用平均水深在沙丘波峰和波谷的简单性。 </li><li>记录来自流量计的信道流量（Q），并计算出平均流速为 Q /（D * w）的 ， 其中 w是水槽的宽度，d是水深。 注意：我们的流量计被插入水槽的再循环回路。 </li><li>测量并记录在试验段的平均底形波长。典型地，测量波长为连续沙丘波峰之间的距离。 </li><li>打开Mousedrop模拟（中的NetLogo平台），并检查所有的测量是在模拟用户界面中指定的变量范围之内。如果测得的参数落在约束范围之外，调整由参数“滑​​块”右键单击仿真参数范围，选择“编辑”，并调整最大/最小值。 </li></ol></li><li>可视化潜流交换。 <ol><li>将相机设置在固定的位置（优选在三脚架）正交指着水槽壁与中心在图片中的测试部分的单个底形。 注意：这将避免倾斜的角度看问题。 </li><li>以一个测试图片来验证条件。调整灯光的反射，如果是一个问题。 </li><li>使用注射器和针头，使2-3小染料我njections靠近水槽壁。确保这些注射形成〜2厘米的圆形有色孔隙水的贴剂在不同的垂直和水平位置。请小心，在注射过程中尽量减少干扰沙床。 注：小体积的染料注射让用户看到更多的细节和查看单个流的路径。 </li><li>记录染料注射的开始时间，并采取的初始图象。 可选：它可以是教育跟踪的初始染料前沿与透明纸标记，使染料运动是容易观察到在实验室中，但是这些轮廓也将阻止在图象的染料方面的一小部分，所以有一个与贸易关闭。 </li><li>捕获在适当的时间间隔染料前沿位置。对于时间间隔摄影，用30秒的时间间隔给予流畅的效果。 </li></ol></li></ol> 3.模拟<ol><li>运行仿真1：Mousedrop和观察到的染料运输比较。<ol><li>打开名为Mousedrop.nlogo仿真脚本。 <img alt="图3" src="/files/ftp_upload/53285/53285fig2.jpg" width="600" /> 图2. Mousedrop。这说明，其中示踪剂是在一次7个不同的实例。 <a href="https://www.jove.com/files/ftp_upload/53285/53285fig2large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> </li><li>调整表 1所示的，以匹配水槽实验条件的物理系统参数（具体地说拉姆达，BedformHeight，BedDepth，HydrCond，孔隙率，ChannelVelocity，深度，和斜率）。请务必输入输入参数时要特别注意单位。 </li><li>调整滑块时间1，时间2等 ，表明时候模拟跟踪颜色会发生变化。设置这些颜色变化，以便于仿真结果与观察的对比匹配观测时间。 注意：如果时间参数都设置为0，模拟将显示在整个单一的颜色。 </li><li>在所有参数设置，点击设置按钮 。 注：底形应该出现在模拟图。 </li><li>点击鼠标拖放按钮，表示虚拟示踪剂的起始位置。需要注意的是在该床的多个位置可以被点击。按住鼠标以释放更多的虚拟示踪剂。当模拟染料的运动，用鼠标或者跟踪染料方面（围绕染料的边界）或填写染区域的整个区域。 注：引入更多的虚拟示踪剂将导致仿真运行更慢。最佳的视觉效果将与计算机的性能有所不同。 </li><li>一旦所有的虚拟示踪剂已放置，你可以点击进入下一个计时按钮，将开始模拟，然后停止它在第一时间，或者你可以点击Go /停止按钮开始SIMUL通货膨胀下去。不要重复点击设置按钮，或示踪剂将不得不重新放置。 注意：一旦仿真开始运行时，速度被根据用于100模拟秒的速度场，然后在新的位置的速度计算计算出基于仿真参数各示踪剂的位置在等式4和5示踪剂移动并且过程重复进行，直至示踪剂离开系统。 </li><li> （可选）， 点击 Go /停止按钮反复暂停/继续模拟。在时间上比较在不同点的模拟和测量染料分布。 </li></ol></li><li>运行仿真2：接口。 <ol><li>打开名为接口脚本。 <img alt="图3" src="/files/ftp_upload/53285/53285fig3.jpg" width="600" /> 图3界面。这说明370示踪剂使用接口模拟通过地下流动。示踪PA部份效果显示，其中每个示踪剂已经因为它是在表面的水的地下界面启动。最终，所有的流动路径应该回归到地表水。 <a href="https://www.jove.com/files/ftp_upload/53285/53285fig3large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> 注：此脚本介绍了虚拟示踪剂在河床表面的通量加权方式的基础上计算出来的地下速度。这提供的水流入（和退出）的相对量的河床在不同位置的视觉表示。 </li><li>点击设置然后去/停止开始。 注意：这将运行使用默认设置的模拟。 再滴？开关被初始设置为关闭，所以累计停留时间分布将被绘制为时间的经过。 </li><li>观察使用默认参数的模拟后，点击进入/停止停止模拟。 </li><li&gt;更改一个或多个参数，然后点击设置然后去/停止 。 注意：这将重新开始模拟与已经选择的参数。 </li></ol></li></ol>

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The authors have nothing to disclose.

中联，水槽示范和粒子跟踪模拟提供了一个全面的介绍潜流流量的的受众。各级参加者提供视觉证据潜流交换的发生引起的河床，并在地下流动路径的可变性强下底形。这些程序可以作为孔隙水流动的一个简单的演示本科生或K-12的学生，也可以用在研究生课程结合了更深入介绍河流水力学，泥沙输移和潜流交换的机制。无论水平如何，使用这种简单的可视化模型作为互动技术可以让学生形成这些...

由于地表水的动作在流，河流或潮间带它创建头梯度驱动的水流入和流出的沉积物1。在河流系统的河床沉积物，其中该交换发生的部分是被称为潜流带2,3。这个区域是非常重要的，因为许多营养物质和污染物的存储，存放，或潜流带4-9范围内改变。的时间示踪剂花费在沉积物的量被称为停留时间。既停留时间和流动通道的位置会影响转化过程。影响流过泥沙的过程中认识的提高是需要预测溶质运移的河流和解决从材料的传播导致，如营养物质（例如沿海缺氧10,11）大环境的问题。尽管潜流交换的重要性，它往往不是在本科课程水文描述，流体力学，水力学等教育工作者希望增加潜流交换他们的课程可能会发现它有用有实验和数值模拟可视化，明确表明了这一过程。 河道弯度，周围的地下水水位和河床地形（如酒吧，河床和生物丘）都会影响潜流交换不同程度12-17。这项研究的重点河床，如沙丘和波纹，这通常是影响潜流流14,15键地貌特征。我们创建了一个数值模拟和实验室实验过有规律的一系列底形的可视化流程。此模拟基于以前的研究有关潜流流路，以容易观察到的系统特性15,18-21的本体。作为这项研究形成了科学背景的模拟，理论的主要方面简要总结如下。底形地形，T（X），计算公式如下： 方程1： <img alt="式（1）" src="/files/ftp_upload/53285/53285eq1.jpg" /> 其中 H是两倍底形的幅度，k是波数，和x是平行于平均河床表面的纵向尺寸。本底形地形的一个例子示于图1。 <img alt="图1" src="/files/ftp_upload/53285/53285fig1.jpg" /> 图1.参数定义和设置由用户控制在 接口 ，示踪粒子被释放在水/沉积物界面焊剂加权方式，并通过沉淀跟踪。如果节目径？“上”水示踪标记，他们一直在，展示自己的路径。当示踪剂返回到地表水，这改变吨他系统中的示踪剂的总数， 再下降时？设置为 “关”。的累积停留时间分布曲线示出这种变化通过绘制残留在沉积物床的初始数量作为时间的函数的示踪剂的数量的比率。如果再滴？是“上”，那么示踪剂让系统被替换在同一个流量加权的方式原厂颗粒，累积情节被禁用。 <a href="https://www.jove.com/files/ftp_upload/53285/53285fig1large.jpg" target="_blank">请点击此处查看该图的放大版本。</a> <table fo:keep-together.within-page="1"><tbody><tr><td> 参数名称 </td><td> 单位 </td><td colspan="3"> 定义 </td><td> 接口 </td><td> Mousedrop </td></tr><tr><td>拉姆达（λ） </td><td>厘米</td><td colspan="3">底形的波长（见图1）&lt;/ TD&gt; <td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td> BedformHeight（H）的</td><td>厘米</td><td colspan="3">在两次底形幅度（见图1） </td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td> BedDepth（D） </td><td>厘米</td><td colspan="3">沉积物的深度（参见图1） </td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td> HydrCond（K） </td><td>厘米/秒</td><td colspan="3">导水率</td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td>孔隙度（θ）的</td><td></td><td colspan="3">孔隙度</td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td> ChannelVelocity（U） </td><td>厘米/秒</td><td colspan="3">平均速度在地表水或通道</td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td>深度（d） </td><td>厘米</td><td colspan="3">水深度（见图1） </td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td>斜率（S） </td><td></td><td colspan="3">在河床和水面坡度</td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><tD&gt; <img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td> NumParticles </td><td></td><td colspan="3">释放到系统的粒子数。 </td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td></td></tr><tr><td> TIMEX（时间1，时间2 ..） </td><td>分</td><td colspan="3">在每个颜色发生变化的时间</td><td></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td> 模拟按钮 </td><td></td><td colspan="3"> 定义 </td><td> 接口 </td><td> Mousedrop </td></tr><tr><td>建立</td><td></td><td colspan="3">设定的最高使用参数显示的模拟</td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td>去/停止</td><td></td><td colspan="3">启动和停止模拟</td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td>步骤</td><td></td><td colspan="3">单击步骤会使一次性地通过。这使得用户可以减缓代码，看看在100秒的情况完全相同。 </td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td></td></tr><tr><td>清晰的路径</td><td></td><td colspan="3">清除所有从屏幕上，他的蓝色粒子的路径</td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td>前进到下一次</td><td></td><td colspan="3">这将导致程序运行，直到下一个颜色变化时（TIMEX）</td><td></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td>鼠标拖放</td><td></td><td colspan="3">这个按钮必须被点击之前的颗粒可以通过点击在地下位置被放置在地下。 </td><td></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td>秀径？ </td><td></td><td colspan="3">如果显示，路径？处于“打开”的水粒子离开的蓝色表示在他们已经一条路径（参见图1）。 </td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td></tr><tr><td>重新降？ </td><td></td><td colspan="3">如果再下降？处于“打开”的颗粒被替换的助熔剂加权方式为每一个颗粒，它退出系统，累积积不起作用。当汉邦第一百退出潜流带如果再滴颗粒在系统中的数量减少？为“关”（见图1）。 </td><td><img alt="复选标记" src="/files/ftp_upload/53285/checkmark.jpg" /></td><td></td></tr></tbody></table> 表1.潜流参数和模拟控制。每个参数，按钮，滑块，可以由用户进行调整，给出在此表以及一个定义。 在该模拟中，两个过程诱导流体速度在沙床上。首先是因为与底形流流的相互作用。的速度头在诱导底形的水/沉积物接口也是近似正弦波，并通过从底形本身22的四分之一波长偏移。的速度头功能在表面地下界面上的幅度已近似从测量值作为16： GE =“总是”&gt; 方程2： <img alt="公式（2）" src="/files/ftp_upload/53285/53285eq2.jpg" /> 其中 U是平均表面水流速度，g为重力常数，d是水（图1中示出）的深度。的速度头函数由下式给出： 公式3： <img alt="公式3" src="/files/ftp_upload/53285/53285eq3.jpg" />该磁头函数然后可以用于通过求解拉普拉斯方程以恒定砂床深度20来计算的地下速度函数的底形为基础的部分。的孔隙水速度的第二组分是由系统，S，其对应于重力梯度头的斜率确定，收率 ​​流在下游方向成正比S / ftp_upload / 53285 / 53285eq_S_inline.jpg“/&gt;的最终功能孔隙水的速度是： 公式4： <img alt="公式4" src="/files/ftp_upload/53285/53285eq4.jpg" /> 公式5： <img alt="公式5" src="/files/ftp_upload/53285/53285eq5.jpg" /> 其中 ，u表示所述纵向速度分量，v是垂直速度分量，K为沉积物的平均水力传导率，是沉积物的平均孔隙率，y是垂直坐标，D是沉积物的深度。 粒子跟踪模拟创建，它使用的NetLogo建模语言和仿真平台23。这两种实现方式（Mousedrop.nlogo和Interface.nlogo）利用这些方程模型HYPorheic流着相同的模拟核心。主要的区别是示踪粒子的初始位置。Mousedrop允许用户放置地下内的任何地方模拟示踪剂。地下速度等式4和5是用来移动示踪以模拟染料注射实验。在接口方面，示踪总是沿着表面/地下边界放在通量加权方式。这模仿递送溶解和悬浮材料从表面的水进入孔隙水，这是理解潜流交换。示踪剂然后地下内移动，直到它重新到达流水。跟踪在水槽染料路径和模拟使用的NetLogo路径产生的流场的流线，只要在观察期间的流动条件和底形形态保持稳定。Interface.nlogo创建累积停留时间分布，其示出了的数量的比值示踪粒子残留在沉积物放置在时间0作为时间的函数示踪粒子的初始数量。 由于在最近的文献调查24所讨论的，仍然大约动手实验室实验与模拟实验室和计算机模型的相对优点中的教育研究界相当大的争议。在一方面，有些人认为“实践经验是学习的心脏”25，并警告说，节省成本的论点可能会助长更换动手基于计算机的模拟实验活动的，对损害学生的理解26。而另一方面，一些研究人员在科学/工程教育认为，模拟是至少一样有效，传统的动手实验室27，或在培养学生为中心的“发现式学习”28讨论计算机模拟的好处。尽管共识并没有被重新疼痛难忍，许多研究人员得出结论认为，理想状态下，计算机模拟应补充，而不是取代，动手实验室实验29,30。也有一些在科学和工程教育的举措，同时耦合物理实验和真实世界的感知与现象的计算机模拟; 例如 ，见“双焦建模”31。 学生可以有更深刻的概念性知识并通过与两个物理系统，以及基于计算机的仿真该系统的相互作用的更好的理解科研过程。此过程涉及具有学生进行溶质运输实验演示引力和底形诱导的潜流交换流动，匹配其自己的实验装置和结果用计算机模拟的相同的现象。这比较有利于学生的重要学习成果，和T的深入讨论他科学的方法和模型/理论建设，并通过数据收集实证验证之间的相互作用。执行此对比后，学生还可以利用基于计算机模拟的好处，通过改变模型参数快速探索多种替代方案。

<table border="0" cellpadding="0" cellspacing="0" width="1244">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:117px;">Flume</td>
			<td style="width:199px;">Engineering Laboratory Design</td>
			<td style="width:125px;">Custom</td>
			<td style="width:804px;">Laboratory flume with clear sides for 24-48 hours</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Flowmeter</td>
			<td>Rosemount&#160;</td>
			<td>8800 vortex&#160;</td>
			<td style="width:804px;">This is located inside the recirculation loop of the flume</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sand</td>
			<td>US. Silica</td>
			<td>F30</td>
			<td style="width:804px;">Research-grade sand to form a layer 10-20 cm deep throughout the flume</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Dye</td>
			<td>Samples from food companies</td>
			<td></td>
			<td style="width:804px;">Water-soluble food grade dye made into an aqueous solution.&#160; Dark colors like red, blue and green work best. (Avoid food dyes in propylene glycol)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Syringe</td>
			<td>HSW</td>
			<td>4100.000V0</td>
			<td style="width:804px;">5-10 mL, e.g. HSW Norm-Ject 2-part disposable syringe</td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Pipetting Needle</td>
			<td>Cadence Science</td>
			<td>7942</td>
			<td>14-gage, 6-in blunt end,&#160; to inject the dye deep into the sand.</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;">Digital Camera</td>
			<td>Any</td>
			<td></td>
			<td style="width:804px;">Digital camera with steady tripod (Time lapse cameras can be used to collect rapid evenly spaced data.)&#160; We used a Nikon D7000.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Ruler</td>
			<td>Any</td>
			<td></td>
			<td style="width:804px;">Transparent is best.</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Measuring Tape</td>
			<td>Any</td>
			<td></td>
			<td style="width:804px;"></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Netlogo Software</td>
			<td>CCL</td>
			<td></td>
			<td><a href="http://ccl.northwestern.edu/netlogo/">http://ccl.northwestern.edu/netlogo/</a></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Mousedrop.nlogo</td>
			<td>Netlogo Commons</td>
			<td align="right">4259</td>
			<td><a href="http://modelingcommons.org/browse/one_model/4259">http://modelingcommons.org/browse/one_model/4259</a></td>
		</tr>
		<tr height="20">
			<td height="20" style="height:20px;">Interface.nlogo</td>
			<td>Netlogo Commons</td>
			<td align="right">4258</td>
			<td><a href="http://modelingcommons.org/browse/one_model/4258">http://modelingcommons.org/browse/one_model/4258</a></td>
		</tr>
	</tbody>
</table>

visualizing hyporheic flow through bedforms using dye experiments and simulation

沉积物孔隙空间和上覆水柱，堪称河流环境潜流交换之间的对流交换，推动河流和许多重要的生物地球化学过程溶质运移。为了提高通过视觉展示这些过程的了解，我们创建了一个潜流流动模拟的多主体的计算机建模平台的NetLogo。仿真结果表明虚拟示踪剂流经长满了二维河床一个河床。沉积物，流，和底形特性被用作输入变量的模型。我们举例说明如何将这些模拟匹配实验观测到的实验室水槽实验，根据测得的输入参数。染料被注入到水槽沉积物形象化孔隙水流动。用于比较的虚拟示踪粒子被放置在模拟中相同的位置。这加上模拟和实验室实验已成功应用于本科和graduaTE实验室直视河孔隙水的相互作用，并展示如何基于物理的流动模拟可以再现环境现象。生了该床的照片通过透明水槽壁和比较它们的染料在模拟同一次的形状。这导致非常相似的趋势，这使得学生更好地理解流动模式的数学模型两者。模拟还允许用户通过运行多个模拟快速查看每个输入参数的影响。这个过程也可以用在研究中的应用来说明基本流程，涉及界面通量和孔隙水运输，并支持定量的过程的建模。

在实验中结合使用模拟可以让学生观察的相似和理想化的数学模型和更复杂的真实系统之间的差异。 图4示出了比较染料注射的照片与Mousedrop模拟的例子。初始照片被用于确定在零时间的放置模拟染料示踪物，然后将模拟运行为34.2分钟，并与在当时拍摄的照片进行比较。总体模型对捕捉染色水的运动超过这个时间间隔一个出色的工作。第一染料斑点，位于底形的背风面，退出?...

Watch this Scientific Journal Video about Visualizing Hyporheic Flow Through Bedforms Using Dye Experiments and Simulation at JoVE.com

Visualizing Hyporheic Flow Through Bedforms Using Dye Experiments and Simulation

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 ...

visualizing-hyporheic-flow-through-bedforms-using-dye-experiments

Research

Education

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JoVE Journal

Civil Engineering

Engineering

Unit 1

Dimensional Analysis, Similitude, and Modeling

SCIENTISTS IN ACTION

12.1K 次观看.  St. Ambrose University. 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. 

视频: Visualizing Hyporheic Flow Through Bedforms Using Dye Experiments and Simulation

Simulation, Fabrication and Characterization of THz Metamaterial Absorbers

Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical1 and experimental demonstration2 of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical3, near IR4, mid IR5 , THz6 , mm-wave7 , microwave8 and radio9 bands. Applications include perfect lenses10, sensors11, telecommunications12, invisibility cloaks13 and filters14,15. We have recently developed single band16, dual band17 and broadband18 THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers19. In our MM absorber the THz radiation is absorbed in a thickness of ~ &lambda;/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems.

This protocol outlines the simulation, fabrication and characterization of THz metamaterial absorbers. Such absorbers, when coupled with an appropriate sensor, have applications in THz imaging and spectroscopy.

模拟，太赫兹超材料吸收器的制备与表征

Metamaterials (MM),  artificial materials engineered to have properties that may not be found in  nature, have been widely explored since the first ...

科研

工程学

Measuring Material Microstructure Under Flow Using 1-2 Plane Flow-Small Angle Neutron Scattering

A new small-angle neutron scattering (SANS) sample environment optimized for studying the microstructure of complex fluids under simple shear flow is presented. The SANS shear cell consists of a concentric cylinder Couette geometry that is sealed and rotating about a horizontal axis so that the vorticity direction of the flow field is aligned with the neutron beam enabling scattering from the 1-2 plane of shear (velocity-velocity gradient, respectively). This approach is an advance over previous shear cell sample environments as there is a strong coupling between the bulk rheology and microstructural features in the 1-2 plane of shear. Flow-instabilities, such as shear banding, can also be studied by spatially resolved measurements. This is accomplished in this sample environment by using a narrow aperture for the neutron beam and scanning along the velocity gradient direction. Time resolved experiments, such as flow start-ups and large amplitude oscillatory shear flow are also possible by synchronization of the shear motion and time-resolved detection of scattered neutrons. Representative results using the methods outlined here demonstrate the useful nature of spatial resolution for measuring the microstructure of a wormlike micelle solution that exhibits shear banding, a phenomenon that can only be investigated by resolving the structure along the velocity gradient direction. Finally, potential improvements to the current design are discussed along with suggestions for supplementary experiments as motivation for future experiments on a broad range of complex fluids in a variety of shear motions.

A shear cell is developed for small-angle neutron scattering measurements in the velocity-velocity gradient plane of shear and is used to characterize complex fluids. Spatially resolved measurements in the velocity gradient direction are possible for studying shear-banding materials. Applications include investigations of colloidal dispersions, polymer solutions, and self-assembled structures.

测量材料在微流使用1-2面流小角中子散射

A new small-angle neutron scattering (SANS) sample environment optimized for studying the microstructure of complex fluids under simple shear flow is ...

Experiments on Ultrasonic Lubrication Using a Piezoelectrically-assisted Tribometer and Optical Profilometer

Friction and wear are detrimental to engineered systems. Ultrasonic lubrication is achieved when the interface between two sliding surfaces is vibrated at a frequency above the acoustic range (20 kHz). As a solid-state technology, ultrasonic lubrication can be used where conventional lubricants are unfeasible or undesirable. Further, ultrasonic lubrication allows for electrical modulation of the effective friction coefficient between two sliding surfaces. This property enables adaptive systems that modify their frictional state and associated dynamic response as the operating conditions change. Surface wear can also be reduced through ultrasonic lubrication. We developed a protocol to investigate the dependence of friction force reduction and wear reduction on the linear sliding velocity between ultrasonically lubricated surfaces. A pin-on-disc tribometer was built which differs from commercial units in that a piezoelectric stack is used to vibrate the pin at 22 kHz normal to the rotating disc surface. Friction and wear metrics including effective friction force, volume loss, and surface roughness are measured without and with ultrasonic vibrations at a constant pressure of 1 to 4 MPa and three different sliding velocities: 20.3, 40.6, and 87 mm/sec. An optical profilometer is utilized to characterize the wear surfaces. The effective friction force is reduced by 62% at 20.3 mm/sec. Consistently with existing theories for ultrasonic lubrication, the percent reduction in friction force diminishes with increasing speed, down to 29% friction force reduction at 87 mm/sec. Wear reduction remains essentially constant (49%) at the three speeds considered.

We present a protocol for using a piezoelectrically-assisted tribometer and optical profilometer to investigate the dependence of ultrasonic wear and friction reduction on linear velocity, contact pressure, and surface properties.

使用超声波润滑实验一压电辅助摩擦试验机和光学轮廓

Friction and wear are detrimental to engineered systems. Ultrasonic lubrication is achieved when the interface between two sliding surfaces is vibrated at ...

Digital Printing of Titanium Dioxide for Dye Sensitized Solar Cells

Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less environmentally damaging with lower processing temperatures presenting a viable and low cost alternative to conventional production. This paper further enhances these environmental credentials by evaluating the digital printing and therefore additive production route for these cells. This is achieved here by investigating the formation and performance of a metal oxide photoelectrode using nanoparticle sized titanium dioxide. An ink-jettable material was formulated, characterized and printed with a piezoelectric inkjet head to produce a 2.6 &#181;m thick layer. The resultant printed layer was fabricated into a functioning cell with an active area of 0.25 cm2 and a power conversion efficiency of 3.5%. The binder-free formulation resulted in a reduced processing temperature of 250 &#176;C, compatible with flexible polyamide substrates which are stable up to temperatures of 350 &#730;C. The authors are continuing to develop this process route by investigating inkjet printing of other layers within dye sensitized solar cells.

This paper investigates the suitability of inkjet printing for the manufacturing of dye-sensitized solar cells. A binder-free TiO2 nanoparticle ink was formulated and printed onto a FTO glass substrate. The printed layer was fabricated into a cell with an active area of 0.25 cm2 and an efficiency of 3.5%.

钛白粉用于染料敏化太阳能电池的数码印刷

Silicon solar cell manufacturing is an expensive and high energy consuming process. In contrast, dye sensitized solar cell production is less ...

Study of Siphon Breaker Experiment and Simulation for a Research Reactor

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent this outflow, a control device is required. A siphon breaker is a type of safety device that can be utilized to control the loss of coolant water effectively.
To analyze the characteristics of siphon breaking, a real-scale experiment was conducted. From the results of the experiment, it was found that there are several design factors that affect the siphon breaking phenomenon. Therefore, there is a need to develop a theoretical model capable of predicting and analyzing the siphon breaking phenomenon under various design conditions. Using the experimental data, it was possible to formulate a theoretical model that accurately predicts the progress and the result of the siphon breaking phenomenon. The established theoretical model is based on fluid mechanics and incorporates the Chisholm model to analyze two-phase flow. From Bernoulli&#39;s equation, the velocity, quantity, undershooting height, water level, pressure, friction coefficient, and factors related to the two-phase flow could be obtained or calculated. Moreover, to utilize the model established in this study, a siphon breaker analysis and design program was developed. The simulation program operates on the theoretical model basis and returns the result as a graph. The user can confirm the possibility of the siphon breaking by checking the shape of the graph. Furthermore, saving the entire simulation result is possible and it can be used as a resource for analyzing the real siphon breaking system.
In conclusion, the user can confirm the status of the siphon breaking and design the siphon breaker system using the program developed in this study.

The siphon breaking phenomenon was investigated experimentally and a theoretical model was proposed. A simulation program based on the theoretical model was developed and the results of the simulation program were compared with experimental results. It was concluded that the results of the simulation program matched the experimental results well.

研究堆虹吸断路器试验与仿真研究

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent ...

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 ...

A 100 KW Class Applied-field Magnetoplasmadynamic Thruster

Applied-field magnetoplasmadynamic thrusters (AF-MPD thrusters) are hybrid accelerators in which electromagnetic and gas dynamic processes accelerate plasma to high speed; they have considerable potential for future space applications with the significant advantages of high specific impulse and thrust density. In this paper, we present a series of protocols for designing and manufacturing a 100 kW class of AF-MPD thruster with water-cooling structures, a 130 V maximum discharge voltage, a 800 A maximum discharge current, and a 0.25 T maximum strength of magnetic field. A hollow tantalum tungsten cathode acts as the only propellant inlet to inhibit the radial discharge, and it is positioned axially at the rear of the anode in order to relieve anode starvation. A cylindrical divergent copper anode is employed to decrease anode power deposition, where the length has been reduced to decrease the wall-plasma connecting area. Experiments utilized a vacuum system that can achieve a working vacuum of 0.01 Pa for a total propellant mass flow rate lower than 40 mg/s and a target thrust stand. The thruster tests were carried out to measure the effects of the working parameters such as propellant flow rates, the discharge current, and the strength of applied magnetic field on the performance and to allow appropriate analysis. The thruster could be operated continuously for significant periods of time with little erosion on the hollow cathode surface. The maximum power of the thruster is 100 kW, and the performance of this water-cooled configuration is comparable with that of thrusters reported in the literature.

The goal of this protocol is to introduce the design of a 100 kW class applied-field magnetoplasmadynamic thruster and relevant experimental methods.

一个100千瓦级的应用场磁等离子体动力学推进器

Applied-field magnetoplasmadynamic thrusters (AF-MPD thrusters) are hybrid accelerators in which electromagnetic and gas dynamic processes accelerate ...

Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope

The quest to understand correlated electronic systems has pushed the frontiers of experimental measurements toward the development of new experimental techniques and methodologies. Here we use a novel home-built uniaxial-strain device integrated into our variable temperature scanning tunneling microscope that enables us to controllably manipulate in-plane uniaxial strain in samples and probe their electronic response at the atomic scale. Using scanning tunneling microscopy (STM) with spin-polarization techniques, we visualize antiferromagnetic (AFM) domains and their atomic structure in Fe1+yTe samples, the parent compound of iron-based superconductors, and demonstrate how these domains respond to applied uniaxial strain. We observe the bidirectional AFM domains in the unstrained sample, with an average domain size of ~50-150 nm, to transition into a single unidirectional domain under applied uniaxial strain. The findings presented here open a new direction to utilize a valuable tuning parameter in STM, as well as other spectroscopic techniques, both for tuning the electronic properties as for inducing symmetry breaking in quantum material systems.

Visualizing Uniaxial-strain Manipulation of Antiferromagnetic Domains in Fe1+YTe Using a Spin-polarized Scanning Tunneling Microscope

Using uniaxial strain combined with spin-polarized scanning tunneling microscopy, we visualize and manipulate the antiferromagnetic domain structure of Fe1+yTe, the parent compound of iron-based superconductors.

利用自旋偏振扫描隧道显微镜对 fe 1+yTe 中的反铁磁领域进行单轴应变操作

The quest to understand correlated electronic systems has pushed the frontiers of experimental measurements toward the development of new experimental ...

Evaluation of an Exclusive Spur Dike U-Turn Design with Radar-Collected Data and Simulation

Traditional U-turn designs can improve operational features obviously, while U-turn diversions and merge segments still cause traffic congestion, conflicts, and delays. An exclusive spur dike U-turn lane design (ESUL) is proposed here to solve the disadvantages of traditional U-turn designs. To evaluate the operation performance of ESUL, a traffic simulation protocol is needed. The whole simulation process includes five steps: data collection, data analysis, simulation model build, simulation calibration, and sensitive analysis. Data collection and simulation model build are two critical steps and are described later in greater detail. Three indexes (travel time, delay, and number of stops) are commonly used in the evaluation, and other parameters can be measured from the simulation according to experimental needs. The results show that the ESUL significantly diminishes the disadvantages of traditional U-turn designs. The simulation can be applied to solve microscopic traffic problems, such as in single or several adjacent intersections or short segments. This method is not suitable for larger scale road networks or evaluations without data collection.

This protocol describes the process of solving a microscopic traffic problem with simulation. The whole process contains a detailed description of data collection, data analysis, simulation model build, simulation calibration, and sensitive analysis. Modifications and troubleshooting of the method are also discussed.

利用雷达采集的数据和仿真评估独家刺堤 U 型转弯设计

Traditional U-turn designs can improve operational features obviously, while U-turn diversions and merge segments still cause traffic congestion, ...

Automated Delivery of Microfabricated Targets for Intense Laser Irradiation Experiments

Described is an experimental procedure that enables high-power laser irradiation of microfabricated targets. Targets are brought to the laser focus by a closed feedback loop that operates between the target manipulator and a ranging sensor. The target fabrication process is explained in detail. Representative results of MeV-level proton beams generated by irradiation of 600 nm thick gold foils at a rate of 0.2 Hz are given. The method is compared with other replenishable target systems and the prospects of increasing the shot rates to above 10 Hz are discussed.

A protocol is presented for automated irradiation of thin gold foils with high intensity laser pulses. The protocol includes a step-by-step description of the micromachining target fabrication process and a detailed guide for how targets are brought to the laser&#39;s focus at a rate of 0.2 Hz.

用于密集激光辐照实验的微制造目标的自动交付

Described is an experimental procedure that enables high-power laser irradiation of microfabricated targets. Targets are brought to the laser focus by a ...