Name: flow patterns by direction and time
Uploaded: 2025-02-13T15:43:18.000Z
Duration: 1 min 23 s
Channel: JoVE

흐름은 차원에 따라 분류할 수 있습니다. 1차원 흐름에서는 직선 파이프를 통해 이동하는 물에서 볼 수 있듯이 속도 및 압력과 같은 특성이 단일 방향을 따라 변합니다.
2차원 흐름은 열린 수로에서 흐르는 물과 같이 길이와 깊이의 변화를 포함합니다.
3차원 흐름은 바람이 건물을 순환하는 것과 같이 세 방향 모두에서 변형이 있어 더 복잡합니다.
흐름은 또한 속도와 유체 입자가 이동하는 방식에 따라 분류됩니다. 가장 일반적인 유형은 안정된 흐름과 불안정한 흐름입니다.
도시 급수 시스템 파이프라인을 통해 이동하는 물과 같은 일정한 흐름은 시간이 지남에 따라 주어진 시점에서 일정하게 유지되는 유체 특성을 가지고 있습니다.
우수 유출 중 속도 및 유속 변화와 같은 불안정한 흐름은 시간이 지남에 따라 유체 특성의 변화를 경험합니다.
또 다른 중요한 차이점은 층류와 난류입니다. 층류는 저속으로 작고 매끄러운 파이프를 통해 이동하는 물처럼 부드럽고 질서 정연한 움직임을 특징으로 합니다.
대조적으로, 난류는 홍수 발생 시 강이나 암거에서 흔히 볼 수 있는 혼란스럽고 불규칙한 유체 움직임을 포함합니다.

흐름 유형 소개

유체 흐름은 차원과 거동에 따라 분류되며, 속도와 압력과 같은 속성이 단일 축을 따라서만 변하는 1차원 흐름이 가장 단순한 형태입니다. 직선 파이프를 통해 움직이는 물은 다른 방향의 변화가 최소이기 때문에 이러한 흐름 유형을 보여줍니다. 1차원 분석은 파이프 길이를 따라 변화하는 것에만 초점을 맞추어 이러한 흐름을 이해하는 데 도움이 됩니다.

2차원 흐름은 다리 갑판과 같은 평평한 표면 위를 움직이는 공기에서 볼 수 있듯이 길이와 높이가 모두 변하는 것을 포함합니다. 변화는 두 방향으로 발생하므로 1차원 흐름보다 계산이 더 복잡합니다. 가장 복잡한 3차원 흐름은 길이, 높이, 깊이의 세 가지 공간 차원이 모두 변하는 것을 포함합니다. 건물 주변을 순환하는 바람은 이러한 유형의 흐름을 보여주며, 여기서 유체 속성은 여러 방향에 걸쳐 다릅니다.

흐름은 또한 유체 속성이 시간이 지남에 따라 어떻게 변하는지에 따라 분류됩니다. 정상 흐름은 속도와 압력과 같은 속성이 시간이 지남에 따라 어느 지점에서나 일정하게 유지되는 상황을 설명합니다. 시립 상수도 시스템의 파이프라인이 전형적인 예입니다. 대조적으로, 폭우 유출과 같은 불안정한 흐름은 시간이 지남에 따라 유체 특성이 변하는 특징이 있습니다. 불안정한 흐름을 분석하려면 속도와 압력의 시간에 따른 변화에 주의해야 합니다.

층류와 난류의 구분도 필수적입니다. 층류는 매끄럽고 질서 있는 유체 이동을 특징으로 하며, 유체 층은 최소한의 혼합으로 평행하게 이동합니다. 토양 층을 통해 스며드는 지하수는 종종 층류를 보입니다. 그러나 난류는 혼란스럽고 불규칙한 움직임을 수반하며, 홍수 시 강에서 종종 볼 수 있습니다. 유체 입자는 복잡한 방식으로 상호 작용하여 소용돌이와 와류를 생성하여 이러한 흐름의 분석을 크게 복잡하게 만듭니다.

흐름은 차원에 따라 분류할 수 있습니다. 1차원 흐름에서는 보이는 것처럼 속도 및 압력과 같은 속성이 단일 방향을 따라 변합니다.

Education

교육

JoVE Core

Civil Engineering

토목공학

Unit 1

제1단원

Fluid Kinematics

유체 운동학

KEY TERMS AND CONCEPTS

주요 용어 및 개념

Introduction to Types of Flows

flow patterns by direction and time

Fluid flow can be grouped by direction and by how it changes over time. The simplest case is one-dimensional flow. In this type, properties such as velocity and pressure change along only one axis. Water moving through a straight pipe is a common example, because changes in other directions are very small.

Two-dimensional flow changes in two directions. It varies in both length and height, so the analysis is more complex than one-dimensional flow. Air moving over a flat surface, such as a bridge deck, shows this pattern.

Three-dimensional flow is the most complex type. It involves changes in length, height, and depth. Wind moving around buildings is an example, since fluid properties can differ in multiple directions.

Flows are also classified by whether they stay the same over time. In steady flow, velocity and pressure remain constant at a point as time passes. A pipeline in a municipal water supply system is a typical example. Unsteady flow is different because fluid properties change over time. Stormwater runoff is one example, and it requires attention to time-dependent changes in velocity and pressure.

Another important split is between laminar and turbulent flow. Laminar flow is smooth and orderly, with fluid layers moving in parallel and very little mixing. Groundwater seeping through soil layers often follows this pattern. Turbulent flow is chaotic and irregular. It often appears in rivers during floods, where swirling eddies and vortices make the motion much harder to analyze.

Flow Patterns by Direction and Time

eulerian and lagrangian flow descriptions

eulerian-and-lagrangian-flow-descriptions

Tracking Fluid Motion in Space and Time

Fluid flow can be described with the Eulerian and Lagrangian methods. These two approaches give different views of the same moving fluid. They are useful in science and engineering because the best method depends on the problem being studied. The Eulerian method looks at fixed points in space. At each location, it measures fluid properties such as velocity, pressure, and temperature as the fluid moves past. This stationary view is useful when studying how a fluid interacts with a solid object.

introduction to types of flows

Fluid flow can be grouped by direction and by how it changes over time. The simplest case is one-dimensional flow. In this type, properties such as velocity and pressure change along only one axis. Water moving through a straight pipe is a common example, because changes in other directions are very small. Two-dimensional flow changes in two directions. It varies in both length and height, so the analysis is more complex than one-dimensional flow. Air moving over a flat surface, such as a...

streamlines, streaklines, and pathlines

Tracing Fluid Motion: Three Flow Paths

Streamlines, streaklines, and pathlines are three ways to describe fluid motion. Each one shows flow from a different angle. Together, they help students compare how a fluid moves in steady and unsteady flow. A streamline is a line that stays tangent to the fluid’s velocity vector at each point. That means the fluid velocity points along the streamline. Streamlines give an instant picture of the flow field, so they are useful for showing the overall direction of flow in a fluid system. In...

control volume and system representations

control-volume-and-system-representations

Tracking Fluid Through Space or Mass

Fluid analysis often uses two linked ideas: the control volume approach and the system approach. Both help describe mass, energy, and momentum transfer, but they focus on different things. One follows a region in space. The other follows a fixed mass of fluid over time. The control volume approach looks at a stationary area in space through which fluid moves. That area is bounded by a control surface, which is the outer edge of the region. A pipe with water flowing through it is a clear...

velocity and acceleration in steady and unsteady flow

velocity-and-acceleration-in-steady-and-unsteady-flow

How Flow Changes Affect Particle Motion

Velocity and acceleration help describe how a fluid particle moves in steady and unsteady flow. A fluid particle follows a pathline, and its velocity depends on both position and time. Acceleration is found by differentiating velocity with respect to time, so it shows how the particle’s motion changes. In a flow field, acceleration can be written using three perpendicular components. These components show how velocity changes over time in different spatial directions. This gives a general way...

reynolds transport theorem

Reynolds Transport and Control Volumes

Reynolds transport theorem links a fluid system to a control volume. It helps explain how the time rate of change of a property can be tracked in fluid dynamics. The theorem uses extensive properties, such as mass, velocity, acceleration, temperature, and momentum. These properties depend on the size of the system. Their intensive forms are the values per unit mass. The total amount of an extensive property in a system at any instant is the sum of the amounts carried by each tiny fluid...

design example: flow through a fire extinguisher

design-example-flow-through-a-fire-extinguisher

Fire Extinguisher Nozzle Flow and Pressure

A pressurized water fire extinguisher uses fluid dynamics to create a fast stream of water. The water is stored at a much higher pressure inside the extinguisher than the surrounding air. When the extinguisher is activated, that pressure difference forces water to flow out quickly. Bernoulli's equation helps predict the exit speed of the water. This equation links pressure and velocity. As pressure drops, velocity increases. In the extinguisher, the high internal pressure is converted into the...

key terms and concepts

Explore how fluid flow changes by direction and time, from one-dimensional and steady flow to turbulent motion in pipes, wind, and rivers.

Flow Patterns by Direction and Time | JoVE K12

JoVE Core Civil Engineering offers a foundational exploration of essential construction materials such as bricks, stones, steel, wood, and concrete, along with fluid mechanics topics like flow over immersed bodies, open channel flow, and dimensional modeling. It also covers key surveying concepts, including leveling, traverse adjustments, curve design, topographic mapping, and geospatial technologies (GPS & GIS). Science-in-action videos showcase laboratory research on materials, fluids, and surveying practices in real-world engineering systems.

Flow Patterns by Direction and Time

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