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相关概念视频

Uniform Depth Channel Flow: Problem Solving01:18

Uniform Depth Channel Flow: Problem Solving

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To calculate the flow rate for a trapezoidal channel, first, identify the bottom width, side slope, and flow depth of the channel. The cross-sectional area (A) corresponding to the depth of flow (y), channel bottom width (B), and side slope (θ) is determined by:Next, calculate the wetted perimeter, which includes the bottom width and the sloped side lengths in contact with the water. Using the values of the cross-sectional area and the wetted perimeter, determine the hydraulic radius by...
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Uniform Depth Channel Flow01:27

Uniform Depth Channel Flow

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Uniform depth channel flow keeps fluid depth consistent along channels such as irrigation canals. In natural channels, such as rivers, approximate uniform flow is often assumed. This condition occurs when the channel’s bottom slope matches the energy slope, balancing potential energy lost from gravity with head loss due to shear stress. This balance prevents depth changes along the channel length, resulting in a steady, uniform flow.Uniform flow in open channels with a constant cross-section...
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Gradually Varying Flow01:29

Gradually Varying Flow

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Gradually varying flow (GVF) in open channels describes situations where water depth changes slowly along the channel due to factors like non-uniform bed slope, channel shape variations, or obstructions. This flow type occurs when the depth adjusts gradually to balance gravitational forces, shear forces, and energy requirements, resulting in a low rate of depth change.Characteristics of Gradually Varying FlowGVF is commonly observed in natural streams, rivers, and canals, where flow depth...
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Accelerating Fluids01:17

Accelerating Fluids

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When a fluid is in constant acceleration, the pressure and buoyant force equations are modified. Suppose a beaker is placed in an elevator accelerating upward with a constant acceleration, a. In the beaker, assume there is a thin cylinder of height h with an infinitesimal cross-sectional area, ΔS.
The motion of the liquid within this infinitesimal cylinder is considered to obtain the pressure difference. Three vertical forces act on this liquid:
979
Steady Flow of a Fluid Stream01:27

Steady Flow of a Fluid Stream

220
Consider a control volume, such as a pipe with solid boundaries, through which fluid flows and changes direction due to the impulse exerted by the resulting force from the pipe walls. In steady flow, the mass of fluid entering the control volume at a given time, t, with velocity v1, is equal to the mass leaving after infinitesimal time dt, with velocity v2.
During this process, the momentum of the fluid within the control volume remains constant over the time interval dt. By applying the...
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Pressure Variation in a Fluid at Rest01:11

Pressure Variation in a Fluid at Rest

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In a fluid at rest, the pressure at any point beneath the fluid surface depends solely on the depth, not on the container's shape or size. This principle, known as hydrostatic pressure, arises because, in stationary fluids, there is no acceleration, meaning the forces within the fluid balance out. Only vertical forces, caused by the weight of the fluid above, contribute to pressure changes with depth.
When measuring pressure at two different levels within the fluid, the difference in...
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基于混合交叉关联光流方法的粒子位移精细化,并假定渐变恒定.

Hu Li1, Guanyu Yan1, Haidong Zhu2

  • 1College of Mechanical and Electrical Engineering, Guilin Institute of Information Technology, Guilin, Guangxi 541004, China.

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概括

本研究引入了一种混合交叉相关光流法 (CC-OFM),用于准确地测量粒子图像速度计 (PIV) 中的粒子运动,尽管强度变化和大位移. 这种新方法提高了准确性,并捕获了更细微的流量细节.

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科学领域:

  • 流体动力学 流体动力学
  • 光学测量技术的使用.
  • 图像处理 图像处理

背景情况:

  • 粒子图像速度计 (PIV) 对激光波动引起的图像亮度变化敏感.
  • 传统的光流方法 (OFM) 在强度变化和PIV中的大位移时失败.
  • 现有的变量OFM缺乏稳定性和准确性,适用于不同照明的PIV应用.

研究的目的:

  • 为PIV开发一种强大的光流方法,可以处理大位移和强度变化.
  • 提高PIV中位移测量的精度和空间分辨率.
  • 为了解决在动态流体流量分析中传统的OFM的局限性.

主要方法:

  • 开发了一种混合交叉相关光流方法 (CC-OFM).
  • 集成的亮度和梯度常数假设在数据期内,以补偿强度变化.
  • 使用合成和实验粒子图像数据评估CC-OFM.

主要成果:

  • 在PIV图像中,CC-OFM表现出高精度和稳定性,具有较大的位移和强度变化.
  • 该方法有效地弥补了图像对之间的照明变化.
  • 与其他位移测量技术相比,CC-OFM实现了更高的性能.

结论:

  • 拟议的CC-OFM显著提高PIV测量的可靠性在具有挑战性的条件下.
  • CC-OFM的高空间分辨率可以详细捕捉流动动态.
  • CC-OFM提供了一种强大的解决方案,用于分析具有显著照明变化的流体流.