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  • You're on an airplane when you feel a sudden jolt.

    你在飛機上時突然感受到飛機一陣震動。

  • Outside your window nothing seems to be happening,

    窗外看起來一切正常

  • yet the plane continues to rattle you and your fellow passengers as it passes through turbulent air in the atmosphere.

    但飛機繼續穿越亂流層時,你和其他乘客持續聽到飛機發出的咯咯聲。

  • Although it may not comfort you to hear it,

    聽到這種聲音,可能無法舒緩你緊張的心情

  • this phenomenon is one of the prevailing mysteries of physics.

    不過這個現象是物理學中最有名的謎團之一。

  • After more than a century of studying turbulence,

    經過一百多年對亂流的研究後

  • we've only come up with a few answers for how it works and affects the world around us.

    對於它是如何運作,以及如何影響我們周遭的世界,我們只找到了一點點答案。

  • And yet, turbulence is ubiquitous, springing up in virtually any system that has moving fluids.

    亂流其實無所不在,幾乎在任何有流體的系統中,它都會出現。

  • That includes the airflow in your respiratory tract.

    這包含你呼吸道裡的氣流。

  • The blood moving through your arteries.

    你動脈裡流動的血液。

  • And the coffee in your cup, as you stir it.

    還有你杯子裡攪拌著的咖啡。

  • Clouds are governed by turbulence,

    亂流是雲的統治者

  • as are waves crashing along the shore and the gusts of plasma in our sun.

    就連打上岸的海浪,和太陽中離子形成的陣風也是一樣。

  • Understanding precisely how this phenomenon works would have a bearing on so many aspects of our lives.

    如何明確地了解這個現象發生的原因,實在是與我們的生活息息相關。

  • Here's what we do know.

    以下是我們確定知道的。

  • Liquids and gases usually have two types of motion:

    液體和氣體通常有兩種移動方式:

  • a laminar flow, which is stable and smooth;

    一種是層流,移動時穩定且平順

  • and a turbulent flow, which is composed of seemingly unorganized swirls.

    一種是亂流,由許多雜亂無章的漩渦所組成。

  • Imagine an incense stick.

    想象一下線香 。

  • The laminar flow of unruffled smoke at the base is steady and easy to predict.

    底部平坦的煙霧層流,穩定且易於預測。

  • Closer to the top, however,

    然而,接近頂部

  • the smoke accelerates, becomes unstable,

    煙霧上升速度加快,變得不穩定

  • and the pattern of movement changes to something chaotic.

    移動模式變得混亂。

  • That's turbulence in action,

    這就是移動中的亂流

  • and turbulent flows have certain characteristics in common.

    亂流有一些共同的特徵。

  • Firstly, turbulence is always chaotic.

    首先,亂流總是混亂無秩序的。

  • That's different from being random.

    但這種混亂又非完全不受拘束的。

  • Rather, this means that turbulence is very sensitive to disruptions.

    相反的,亂流對於干擾非常敏感。

  • A little nudge one way or the other will eventually turn into completely different results.

    不同的干擾,即便只是輕微的,最終也會造成完全不同的結果。

  • That makes it nearly impossible to predict what will happen,

    這使得亂流幾乎無法預測

  • even with a lot of information about the current state of a system.

    即使有很多資訊可以偵測到目前氣流狀態,但是亂流仍然難以預測。

  • Another important characteristic of turbulence is the different scales of motion that these flows display.

    另一個很重要的亂流的特徵,就是這種氣流有不同的強度。

  • Turbulent flows have many differently-sized whirls called eddies, which are like vortices of different sizes and shapes.

    亂流裡有很多大大小小的漩渦,形成不同形狀和大小的渦流。

  • All those differently-sized eddies interact with each other,

    這些大小不同的漩渦彼此相互作用

  • breaking up to become smaller and smaller

    分裂變得越來越小

  • until all that movement is transformed into heat,

    直到所有的運動在一個稱為「能量串跌」的過程中

  • in a process called theenergy cascade."

    轉化為熱量。

  • So that's how we recognize turbulence

    這就是我們所認識的亂流 –

  • but why does it happen?

    但為甚麼亂流會發生呢?

  • In every flowing liquid or gas there are two opposing forces:

    在每個流動的液體或氣體中,都存在著兩種相反的作用力:

  • inertia and viscosity.

    慣性和黏性。

  • Inertia is the tendency of fluids to keep moving,

    慣性使液體持續流動

  • which causes instability.

    也是造成不穩定性的原因

  • Viscosity works against disruption,

    黏性是一種阻力

  • making the flow laminar instead.

    使其流動趨向平穩。

  • In thick fluids such as honey,

    像蜂蜜這種濃稠的液體裡

  • viscosity almost always wins.

    黏性通常大於慣性。

  • Less viscous substances like water or air are more prone to inertia,

    像水或空氣這種較少黏性的物質,通常是慣性大於黏性

  • which creates instabilities that develop into turbulence.

    而慣性會造成不穩定性,然後演變成亂流。

  • We measure where a flow falls on that spectrum

    我們使用雷諾數來估算

  • with something called the Reynolds number,

    一個流體是處在穩定或混亂的狀態

  • which is the ratio between a flow's inertia and its viscosity.

    雷諾數是流體的慣性與黏性的比值。

  • The higher the Reynolds number,

    雷諾數越高

  • the more likely it is that turbulence will occur.

    亂流發生的機率就越高。

  • Honey being poured into a cup, for example,

    舉例來說,蜂蜜倒入一個杯中的雷諾數

  • has a Reynolds number of about 1.

    大概是 1。

  • The same set up with water has a Reynolds number that's closer to 10,000.

    水倒入杯中的雷諾數則將近 10,000。

  • The Reynolds number is useful for understanding simple scenarios,

    雷諾數可以幫助我們了解在單純環境下的流體

  • but it's ineffective in many situations.

    但是在許多時候,雷諾數是無用的。

  • For example, the motion of the atmosphere is significantly influenced

    例如,地心引力和地球轉動等

  • by factors including gravity and the earth's rotation.

    皆為影響大氣層流動的重要因素。

  • Or take relatively simple things like the drag on buildings and cars.

    或拿些相對簡單的事為例,像是建築物和車子的阻力。

  • We can model those thanks to many experiments and empirical evidence.

    藉著許多實驗和經驗的證據,我們可以模擬出類似的情況。

  • But physicists want to be able to predict them through physical laws and equations

    但就像我們能模擬行星運行軌道或電磁場一樣

  • as well as we can model the orbits of planets or electromagnetic fields.

    物理學家想要用物理定律和方程式來預測亂流變化。

  • Most scientists think that getting there will rely on statistics and increased computing power.

    大多科學家認為,想要達成這個目標,必須依靠統計數據,和增強計算能力。

  • Extremely high-speed computer simulations of turbulent flows

    利用超級電腦模擬亂流

  • could help us identify patterns that could lead to a theory

    可以幫助我們辨認亂流不同的模式,進而發展出一套理論

  • that organizes and unifies predictions across different situations.

    這種理論可以將各種預測加以整合。

  • Other scientists think that the phenomenon is so complex

    但其他科學家認為亂流現象太過複雜

  • that such a full-fledged theory isn't ever going to be possible.

    要有這麼完整的理論是不可能的。

  • Hopefully we'll reach a breakthrough,

    希望未來我們能有所突破

  • because a true understanding of turbulence could have huge positive impacts.

    因為真正地了解亂流,將對我們極有幫助。

  • That would include more efficient wind farms;

    包括了更高效的風力發電場

  • the ability to better prepare for catastrophic weather events;

    更有效地因應極端惡劣的天氣

  • or even the power to manipulate hurricanes away.

    甚至包括操控颶風的能力。

  • And, of course, smoother rides for millions of airline passengers.

    當然,還有為飛機上眾多乘客帶來更平穩的飛行旅程。

  • Despite how difficult it is to explain turbulence mathematically,

    儘管用數學方法來解釋亂流非常困難

  • Vincent Van Gogh was able to capture it with a sounding accuracy

    但文森.梵谷卻能夠在他的代表性畫作「星夜」中

  • in his iconic painting "The Starry Night".

    精準地將它描繪出來。

  • Watch this video to learn more about the surprising man behind his masterpiece.

    請觀看這部影片,透過他的傑作來更多的了解這個鬼才。

You're on an airplane when you feel a sudden jolt.

你在飛機上時突然感受到飛機一陣震動。

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B2 中高級 中文 美國腔 TED-Ed 流體 飛機 漩渦 氣流 預測

湍流:偉大的物理學未解之謎之一--托馬斯-喬爾。 (Turbulence: one of the great unsolved mysteries of physics - Tomas Chor)

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    Amy.Lin 發佈於 2021 年 01 月 14 日
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