Name: hydrogen bubble flow around a cylinder
Uploaded: 2023-04-30T07:02:00.000Z
Duration: 10 min 32 s
Channel: JoVE

1. 制备连续的气泡膜：
<ol>
	<li>根据图3所示的电路图设置设备。</li>
	<li>将正极电极固定在测试段下游端的水中（参见图4参考）。</li>
	<li>将负极电极置于上游靠近关注点的位置，以便在水流到达研究对象之前将气泡释放到流场中（参见图4参考）。水体在两个电极之间形成电路通路。</li>
	<li>启动流动装置</li>
	<li>将频率控制器的旋钮调至位置2，此时流量约为9×10-4 m3/s。</li>
	<li>开启直流电源，并将电压升至约25 V，电流将自动稳定在约190 mA。</li>
	<li>将信号发生器的波形设置为方波（符号：<img src="/files/ftp_upload/10435/10435eq018.jpg" alt="静态平衡示意图；ΣFx=0；用于教学的力平衡图示。" data-altupdatedat="1761830439000">）。该设置产生一个0 V - 5 V的方波信号，在高电平时激活固态继电器（闭合电路），在低电平时断开电路。</li>
	<li>对于本特定情况，方波的频率并不重要，只需非零即可。</li>
	<li>将信号发生器的直流偏置调至最大（+5 V）。在此设置下，电路始终闭合，系统持续产生气泡。</li>
</ol>
<img alt="电解装置中电极配置的信号发生器直流电路示意图。" src="/files/ftp_upload/10435/10435fig3.jpg" data-altupdatedat="1761830439000" data-alt="图3"> 
图3. 连接示意图。
<img alt="电解装置中电极配置的信号发生器直流电路示意图。" src="/files/ftp_upload/10435/10435fig3.jpg" data-altupdatedat="1761830439000" data-alt="图 4"> 
图 4. 测试段。流动方向从左至右。负极产生一层氢气泡，并随流动被带走。正极设置在测试段的下游端，以避免其干扰。<a href="//cloudfront.jove.com/files/ftp_upload/10435/10435fig4large.jpg" target="_blank">请点击此处查看此图的放大版本。</a>

2. 生成时间线：
<ol>
	<li>启动流动装置</li>
	<li>将频率控制器的旋钮调至位置 2，此时流速约为 9×10-4 m3/s。</li>
	<li>打开直流电源，将电压升至约 25 V，电流将自动稳定在约 190 mA。</li>
	<li>将信号发生器的波形设置为方波（符号：<img src="/files/ftp_upload/10435/10435eq018.jpg" alt="静力平衡示意图；ΣFx=0；用于教学的力平衡图示。" data-altupdatedat="1761830439000">），以产生 0 V - 5 V 的方波信号，高电平时激活固态继电器（闭合电路），低电平时关闭继电器（断开电路）</li>
	<li>将信号发生器的直流偏置设置为 +1 V。</li>
	<li>将信号发生器中方波的频率设置为 10 Hz。</li>
	<li>将方波的对称性略微调为负值（-2），以在保持正确频率的同时增加时间线之间的间隔。</li>
</ol>
3. 利用流线研究冯·卡门涡街：
<ol>
	<li>使用卡尺测量圆柱杆的直径<img src="/files/ftp_upload/10435/10435eq019.jpg" alt="静力平衡方程 ΣFx=0，示意图，用于说明物理原理和力的平衡" data-altupdatedat="1761830439000">，测量时采用国际单位制（m）。</li>
	<li>将一根圆柱形杆固定在负极下游位置。</li>
	<li>将高强度放电灯的光线投射到氢气泡层上。确保光源不直接位于视线上游，以避免成像系统过饱和。</li>
	<li>调整可视化系统与圆柱杆对齐，使摄像机前方仅能看到其圆形端面。</li>
	<li>在可视化窗口内且位于圆柱杆下游处添加一个标记，作为单位时间内计数涡旋脱落周期的参考点。</li>
</ol>
4. 圆柱绕流的数据分析：
<ol>
	<li>确定从机器单位到实际空间单位的转换系数：
	<ol>
		<li>测量杆在气泡板上投射的阴影宽度（参见图2(A)作为参考）。应在杆的位置直接进行测量，以避免因距离导致的畸变。此值即为以机器单位表示的杆直径，<img src="/files/ftp_upload/10435/10435eq020.jpg" alt="静力平衡方程 ΣFx=0 示意图；物理力分量分析" data-altupdatedat="1761830439000">（单位为点或像素，取决于格式）</li>
		<li>使用以下公式确定从机器单位到实际单位的转换系数： 
		<img src="/files/ftp_upload/10435/10435eq021.jpg" alt="放大率公式，M=Di/Do，光学与透镜计算用公式图示。" data-altupdatedat="1761830439000"></li>
	</ol>
	</li>
	<li>流速的测定：
	<ol>
		<li>选择钝体上游一组未发生畸变的时间线。</li>
		<li>以机器单位测量该组中第一条与最后一条时间线之间的距离，<img src="/files/ftp_upload/10435/10435eq022.jpg" alt="静力平衡方程 ΣFx=0，显示作用力的示意图，教育用物理概念。" data-altupdatedat="1761830439000">（单位为点或像素）。</li>
		<li>记录该组中时间线的数量，<img src="/files/ftp_upload/10435/10435eq023.jpg" alt="静力平衡示意图，ΣFx=0，包含力与力矩，用于说明平衡条件。" data-altupdatedat="1761830439000">。</li>
		<li>记录信号发生器输出的方波信号频率，<img src="/files/ftp_upload/10435/10435eq024.jpg" alt="傅里叶变换公式，频率域转换示意图，信号处理方法。" data-altupdatedat="1761830439000">。</li>
		<li>根据以下公式确定来流速度： 
		<img src="/files/ftp_upload/10435/10435eq025.jpg" alt="静力平衡公式 U∞=L·ftl/(Ntl·M)；适用于工程计算。" data-altupdatedat="1761830439000"></li>
	</ol>
	</li>
	<li>雷诺数的测定：
	<ol>
		<li>查找工作流体的运动粘度（例如水 <img src="/files/ftp_upload/10435/10435eq026.jpg" alt="粘度公式，ν=1.004×10⁻⁶，计算示意图，流体力学概念，物理分析。" data-altupdatedat="1761830439000"> m2/s）。</li>
		<li>使用公式(1)计算雷诺数。其中，采用步骤3.1中测得的杆直径（<img src="/files/ftp_upload/10435/10435eq027.jpg" alt="静力平衡 ΣFx=0，MA=0 在力图中表示；用于力学分析的矢量与角度。" data-altupdatedat="1761830439000">），由公式(5)确定的来流速度（<img src="/files/ftp_upload/10435/10435eq001.jpg" alt="U∞ 符号，表示稳态速度，用于流体动力学方程与计算。" data-altupdatedat="1761830439000">），以及步骤4.3.1中确定的运动粘度。</li>
	</ol>
	</li>
	<li>斯特劳哈尔数的测定：杆后尾流中的涡旋运动速度与自由流中的时间线速度不同，因此需要独立估算涡旋脱落频率。
	<ol>
		<li>在杆下游定义一个固定的参考位置。该参考可以是附着在风洞外壁的一根细线，也可以是在流动过程视频中添加的一条数字线。</li>
		<li>在给定时间段 <img src="/files/ftp_upload/10435/10435eq029.jpg" alt="热扩散示意图；热传递方程；显示能量流动；用于教学。" data-altupdatedat="1761830439000"> 内，统计穿过该参考位置的涡旋脱落周期数 <img src="/files/ftp_upload/10435/10435eq028.jpg" alt="反应机理示意图，运动学变量 N_s，动力学方程分析。" data-altupdatedat="1761830439000">。一个涡旋脱落周期如图2(A)所示。</li>
		<li>根据以下公式计算脱落频率： 
		<img src="/files/ftp_upload/10435/10435eq030.jpg" alt="频率计算公式 \( f_s = \frac{N_s}{T} \)，用于信号处理分析。" data-altupdatedat="1761830439000"></li>
		<li>将公式(5)和(6)的结果代入公式(2)，计算斯特劳哈尔数。</li>
	</ol>
	</li>
</ol>

本研究展示了利用氢气泡从圆柱体周围流动的图像中提取定性和定量信息的方法。这些实验提取的定量信息包括自由来流速度（<img src="/files/ftp_upload/10435/10435eq001.jpg" alt="U∞ 符号，表示稳态速度，用于流体动力学方程和计算。" data-altupdatedat="1761830439000">）、涡旋脱落频率（<img src="/files/ftp_upload/10435/10435eq009.jpg" alt="静力平衡，ΣF=0，受力分析图，用于说明物体上力和力矩的平衡。" data-altupdatedat="1761830439000">）、雷诺数（Re）和斯特劳哈尔数（St）。特别是，St 与 Re 的关系结果与以往研究[3]表现出非常好的一致性。
由于当前实验中使用的流速较慢，气泡层中的扰动会产生条纹状的气泡层。这些条纹本质上是迹线。当氢气气泡层向下游移动时，这些迹线会变粗并变得更加不规则。这是自由来流中湍流强度所致。随着风洞流速的增加，该效应会减弱，因为气泡在发生显著扩散之前便已离开测试段。此外，通过在电极丝上涂...

钝体绕流流动的可视化

Visualization of Flow Past a Bluff Body

来源：Ricardo Mejia-Alvarez，Hussam Hikmat Jabbar 和 Mahmoud N. Abdullatif，密歇根州立大学机械工程系，美国密歇根州东兰辛市
由于其控制定律的非线性特性，流体运动会产生复杂的流动模式。数百年来，人们对这些模式的本质进行了深入研究。尽管个人计算机和超级计算机被广泛用于推导流体流动模式，但其能力仍不足以准确确定复杂几何结构或高惯性流动（例如，动量主导于黏性阻力时）下的精确流动行为。鉴于此，人们已开发出多种实验技术，用以清晰呈现流动模式，这些技术能够达到理论和计算工具无法触及的流动状态和几何条件。
本演示将研究绕流钝体的流体流动。钝体是指由于其形状导致大部分表面发生流动分离的物体。这与流线型体（如翼型）相反，后者沿流动方向排列，产生的流动分离较少。本研究的目的是利用氢气泡作为可视化流动模式的方法。氢气泡通过直流电源在水中进行电解产生，即将电源电极浸入水中。氢气泡在负极形成，负极需使用极细的金属丝，以确保气泡保持微小，从而更有效地追踪流体运动。该方法适用于稳态和非稳态层流，基于描述物体周围流动特性的基本流线原理。[1-3]
本文重点描述该技术的实施过程，包括有关设备及其安装的详细信息。随后，利用该技术演示两种基本流线的使用方法，以表征绕圆柱体的流动。这些流线可用于估算一些重要的流动参数，如流速和雷诺数，并用于确定流动模式。

图2展示了冯·卡门涡街氢气泡可视化的两个典型结果。图2(A) 显示了由氢气泡片中的扰动所呈现的迹线场示例。该图像用于提取以机器单位表示的圆杆直径。图2(B) 显示了脉线场的一个示例，用于估算来流流体速度。本实验提取的参数汇总于表2中。
表 2．圆柱绕流的典型结果。
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>参数</td>
			<td>...

来源：Ricardo Mejia-Alvarez、Hussam Hikmat Jabbar 和 Mahmoud N. Abdullatif，美国密歇根州立大学机械工程系，东兰辛...

由于其控制方程的非线性特性，流体运动会产生复杂的流动模式。这些流动模式受多种因素影响，其中之一便是流体绕过障碍物（如钝体）时的流动。钝体是指因其形状而在大部分表面引起流动分离的物体。根据流动条件的不同，这种流动可能变得不稳定，从而在物体尾流区产生称为涡旋脱落的振荡流动模式。本视频将介绍由钝体引起的流动分离和涡旋脱落的基本原理，并演示一种用于可视化相应流动模式的技术。首先，考虑速度为 U∞（称为自由来流速度）的水作均匀定常流动，流经一个圆形圆柱体。物体表面的边界层分离会导致在物体周围形成涡旋，这些涡旋最终脱离并进入尾流区域。当发生周期性脱离时，涡旋在物体后方产生交替的低压区域。这一过程称为卡门涡街（Von Karman vortex street）。这种周期性模式在特定雷诺数范围内出现，雷诺数是一个无量纲参数，定义为惯性力与粘性力之比。其中，ν 是流体的运动粘度，V 是特征速度（在本例中即 U∞），D 是圆柱体直径。例如，在接下来的演示实验装置中，当雷诺数约为 5 时，圆柱体后方会出现两个稳定的反向旋转涡旋。随着雷诺数的增加，这些涡旋沿流动方向被拉长。当雷诺数达到约 37 时，尾流变得不稳定，并由于压力与动量之间的不平衡而呈现正弦振荡。涡旋从圆柱体脱落的频率并非恒定，而是随雷诺数的数值变化。这一脱落频率由斯特劳哈尔数（Strouhal number）表征，这是另一个无量纲参数。斯特劳哈尔数的定义如公式所示，其中 f 为涡旋脱落频率。对流动模式的实验分析使用四种类型的流线。迹线（path line）是指某一特定流体粒子随流动运动所遵循的路径。脉线（streak line）是指所有起源于同一位置的流体粒子在连续时刻所构成的轨迹。流线（streamline）是一条假想的曲线，其在每一瞬间都与速度场在局部相切。需要注意的是，在定常流动条件下，迹线、脉线和流线三者重合。在当前流动中，这对应于钝体前方足够远的上游区域，或远离其尾流影响的区域。而在非定常流动条件下，迹线、脉线和流线则彼此不同。在当前流动中，这主要对应于钝体的尾流区域。最后，时线（timeline）是指在同一时刻被释放到流场中的一系列流体粒子所构成的连续轨迹。在接下来的实验中，我们将使用连续的微小氢气泡薄层，通过时线和脉线来分析流动模式。现在，让我们来看一下如何设置该流动实验。首先，根据所示的电路图组装设备。将正极电极固定在测试段下游端的水中。接着，将负极电极固定在上游位置，应靠近气泡在水流到达研究对象之前释放入流的位置。启动流动装置，然后将频率控制器的旋钮调至位置2，以建立约0.04米/秒的平均流速。该流速对应的流量约为50×10⁻⁵立方米/秒。现在打开直流电源，将电压调至约25伏，电流约为190毫安。在信号发生器上，将输出设置为方波，信号为0伏至5伏的方波信号，高电平时闭合电路，低电平时断开电路。将直流偏置调至最大值5伏，使电路始终闭合，系统持续产生气泡。为生成时间线，将信号发生器中的直流偏置调整为1伏，然后将方波频率设置为10赫兹，流动中将生成时间线。接着将方波的对称性设置为-2，以增加时间线之间的间距。首先使用卡尺以国际单位制（SI）测量圆柱杆的直径。将圆柱杆固定在负电极的下游位置。对氢气泡层施加高强度光照，注意光源不能直接位于视线正后方，以避免成像系统过饱和。调整观测系统与圆柱杆对齐，使摄像头前方仅显示圆柱杆的圆形端面。在观测窗口内以及圆柱杆下游位置添加一个标记，作为参考点用于统计涡旋脱落周期。首先测量杆在气泡膜上投射的阴影宽度。测量时应紧邻杆的位置进行，以避免因距离导致的畸变。利用杆的直径确定从设备单位到实际单位的换算系数。接下来，选择一组远离钝体及其尾流影响区域、且几乎无畸变的时间线。以设备单位测量该组中第一条与最后一条时间线之间的距离 L。统计该组内时间线的数量，并记录方波的频率。根据以下公式确定来流速度。然后，结合水的运动黏度，计算雷诺数。接下来，通过观察杆后尾流中的涡旋来确定斯特劳哈尔数。注意，涡旋的移动速度与主流区时间线的速度不同。以固定的细线作为参考，统计在指定时间段内通过参考点的涡旋脱落周期数 NS，计算脱落频率。再利用所得结果计算斯特劳哈尔数。现在我们已经讨论了实验步骤和分析方法，接下来让我们来看一下结果。结果的有效性可以通过雷诺数与斯特劳哈尔数之间的关系来确定。系数 St* 和 m 取决于雷诺数的范围，可在文献中查到。本示例中的雷诺数为 115，因此可利用相应的 St* 和 m 值计算斯特劳哈尔数。计算得到的斯特劳哈尔数为 0.172，与实测值 0.169 非常接近。当本实验在不同操作参数下进行时，雷诺数和斯特劳哈尔数的计算结果均与两者之间的数学关系高度吻合。这表明气泡法在研究钝体周围流动模式方面具有良好的适用性。理解流动模式对于多种工程应用的设计与运行至关重要。桥梁桥墩和海上石油钻井平台的设计必须能够承受水流经过结构时产生的湍流。了解特定结构所暴露的涡旋脱落频率对其设计至关重要。在这一方面，工程师必须确保结构的固有频率不会与涡旋脱落频率发生共振，因为这必然会导致结构的灾难性破坏。研究流线型物体（如机翼或船体）周围的流体流动同样至关重要。通过利用流线，工程师可以确定飞机失速的角度，甚至可以根据流速估算升力特性。您刚刚观看了 JoVE 关于在钝体周围可视化流线的视频。您现在应该理解了流体流动模式和卡门涡街的基本原理，如何设置实验来可视化这些流动模式，以及如何研究流动行为。感谢观看。

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通过钝体流的可视化

hydrogen bubble flow around a cylinder

Hydrogen bubble flow around a circular cylinder shows how fluid moves past a bluff body. A bluff body is an object with a shape that causes separated flow over most of its surface. This is different from a streamlined body, such as an airfoil, which stays aligned with the stream and causes less flow separation.

Fluid motion can form complex patterns because its governing laws are non-linear. Scientists have studied these patterns for centuries. Computers and supercomputers can help predict flow, but they may still fall short for complex shapes or highly inertial flows, where momentum dominates over viscous resistance.

To make these patterns visible, the method uses hydrogen bubbles created by electrolysis. A DC power source is used with electrodes submerged in water. Hydrogen forms at the negative electrode. That electrode must be a very fine wire so the bubbles stay small and can track the fluid motion more effectively.

This technique works for steady and unsteady laminar flows. It uses basic flow lines to show the nature of the flow around objects. The demonstration also uses two basic flow lines to describe the flow around a circular cylinder. These flow lines help estimate flow velocity and the Reynolds number, and they help determine the flow pattern.

Hydrogen Bubble Flow Around a Cylinder

buoyancy and drag on immersed bodies

Measuring Drag on Rising Bubbles

Objects, vehicles, and organisms in fluids experience buoyancy, drag, and lift. Buoyancy is the upward force from the fluid’s weight. Drag is the resistive force that acts opposite motion. Lift is the force perpendicular to the direction of motion. These forces matter in engineering and in the study of swimming and flying organisms. Predicting and measuring them helps explain how bodies move through a fluid medium. It also supports the design of vehicles that travel through liquids or gases. <br...

stability of floating vessels

How Cargo Changes Boat Stability

Boat stability depends on hull shape and internal mass distribution. A stable vessel can self-right after it is rolled to one side by an outside force. Careful hull design helps seagoing vessels stay stable with a low draft, which is the submerged depth of the hull. That can improve maneuverability and reduce drag. This experiment uses a model boat with an adjustable center of mass, which represents different cargo loadings. The boat is also modified for automated tracking of its roll angle.

propulsion and thrust

Static Thrust Testing in Propulsion Systems

Propulsion systems create thrust by speeding up a surrounding fluid or high-temperature combustion products. Aircraft, rockets, and ships all use this basic idea. When the fluid leaves at high velocity, conservation of momentum produces an effective force on the vehicle. Thrust is often checked with static thrust tests. In these tests, the propulsion system is fixed to an instrumented mount, and the holding force on the mount is measured as thrust. This setup lets the system run while the...

piping networks and pressure losses

Measuring Pressure Drop in Pipe Components

This experiment measures pressure drop in pipe components used in internal flow systems. Friction from channel walls, fittings, and obstructions can turn fluid pressure into heat, which reduces the pressure available for flow. A piping network is built with straight tubing, helical tube coils, and elbow fittings with sharp 90° bends. Pressure loss is measured across each component set with manometers, which show fluid pressure by the height of liquid in an open vertical column. The measured...

quenching and boiling

Heat Transfer During Metal Quenching

Controlled heating followed by rapid cooling is a key step in many materials processing applications. This heat-treating process can make a material harder. That matters for cutting tools and for surfaces that must resist wear. The rapid cooling stage is called quenching. It is often done by placing the material in a fluid bath, such as water or oil. Quenching heat transfer can happen by forced convection, when fast movement through the coolant drives heat transfer, or by free convection, when...

hydraulic jumps

Water Flow Slowing in a Hydraulic Jump

Hydraulic jumps show how fast open-channel water can suddenly slow down and rise. When water moves at high velocity along an open channel, the flow can become unstable. Small disturbances can make the upper surface jump to a higher level. This abrupt rise is called a hydraulic jump. As the water level increases, the average flow velocity drops. The fast-moving water also loses kinetic energy, and that energy is dissipated as heat. Engineers often build hydraulic jumps into large water works,...

heat exchanger analysis

Measuring Heat Transfer in a Tube Exchanger

Heat exchangers move thermal energy between two fluid streams and are common in energy systems. They appear in car radiators, refrigerator evaporators, and cooling towers in power plants. In each case, heat moves from one fluid to another, either directly or through a surface. This experiment focuses on a water-to-water tube-in-tube heat exchanger. The setup is built and then tested with temperature and flow rate measurements. These measurements are used to find the heat transfer rate, or Q,...

introduction to refrigeration

Hand-Pump Vapor Compression Refrigeration

Vapor compression refrigeration shows how refrigerators, freezers, air-conditioning systems, and heat pumps remove heat. It is the dominant refrigeration technology used in many everyday devices. In this cycle, cooling happens when refrigerant evaporates at low pressure. The absorbed thermal energy is then released to the surroundings when the refrigerant condenses at high pressure. The compressor is the part that raises the working fluid from low pressure to high pressure. Mechanical work is...

hot wire anemometry

Measuring Turbulent Flow with Hot Wires

Hot-wire anemometry measures fast changes in fluid flow with a thin heated wire. Its very short time response makes it useful for rapidly fluctuating motion, especially turbulent flows. This experiment demonstrates how hot-wire anemometry is used in practice. It shows a method for tracking flow conditions when quick changes matter. The setup highlights why a hot-wire anemometer can capture details that slower sensors may miss.

measuring turbulent flows

Hot-Wire Analysis of a Turbulent Jet

Hot-wire anemometry is used to measure a turbulent jet and study its fast changes in speed. Turbulent flows have very high-frequency fluctuations, so they require instruments with a fast time response for proper measurement. A hot-wire anemometer has that short response time and can capture these rapid velocity changes. A previously calibrated hot-wire probe is used to collect velocity data at different positions within the jet. These measurements show how the flow varies across the turbulent...

visualization of flow past a bluff body

Hydrogen bubble flow around a circular cylinder shows how fluid moves past a bluff body. A bluff body is an object with a shape that causes separated flow over most of its surface. This is different from a streamlined body, such as an airfoil, which stays aligned with the stream and causes less flow separation. Fluid motion can form complex patterns because its governing laws are non-linear. Scientists have studied these patterns for centuries. Computers and supercomputers can help predict...

jet impinging on an inclined plate

Measuring Jet Force on an Inclined Plate

A plane jet striking an inclined plate shows how fluid flow can exert force on a surface. The experiment focuses on how dynamic pressure changes into static pressure at the plate and how that change affects the load on the structure. Pressure is measured along the plate to build a pressure distribution. The plate has small perforations called pressure taps, and these taps connect through hoses to a scanning valve. The scanning valve sends pressure from one tap at a time to a diaphragm pressure...

conservation of energy approach to system analysis

conservation-of-energy-approach-to-system-analysis

Fan-Pipe Flow and Valve Pressure Loss

This experiment examines steady, incompressible flow in a short pipe with a gate valve. It uses the energy conservation equation to track how pressure and flow change through the system. The gate valve is gradually closed, and its effect on the flow conditions is measured. The setup shows how energy dissipation helps a valve restrict flow. It also links the pipe system to the fan that drives the flow by comparing the system curve with the fan’s characteristic curve. The same pressure-based...

mass conservation and flow rate measurements

mass-conservation-and-flow-rate-measurements

Calibrating a Smooth Contraction Flowmeter

Mass conservation can be used to calibrate a smooth contraction as a flowmeter. The experiment uses a control volume, or CV, formulation. A control volume is a simplified region used to study the macroscopic effect of flow on an engineering system. This approach focuses on the main mass exchange in the system rather than the detailed flow pattern. It is a complementary method to differential analysis, which looks at the flow in more detail. In design work, the CV method can give an engineer an...

determination of impingement forces on a flat plate with the control volume method

determination-impingement-forces-on-flat-plate-with-control-volume

Jet Impact and Plate Force Measurement

A plane jet striking a flat plate creates a force that can be estimated from changes in linear momentum. This experiment uses a control volume formulation to study that force at different angles. A control volume is an imaginary closed surface that surrounds the flow region and helps simplify the analysis. The control volume approach focuses on the macroscopic effect of flow on an engineering system. It does not try to describe every detail of the fluid motion. Instead, it identifies the main...

mechanical engineering

该系列介绍了一系列的概念, 是理解和设计机械系统的关键。每个视频检查一个特定的主题, 并描述基本的分析方法, 通常用于了解物理行为。

See how hydrogen bubbles are used to visualize fluid flow past a circular cylinder, estimate velocity and Reynolds number, and reveal flow patterns.

Hydrogen Bubble Flow Around a Cylinder

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