Reynolds Number - Numberphile

Second of three videos we're doing on Navier Stokes and related fluid stuff... featuring Tom Crawford.
More links & stuff in full description below ↓↓↓

NUMBERPHILE

Videos by Brady Haran
Editing and animation: Pete McPartlan

[numberphile]

Full Playlist: @t
Part 1 (Navier-Stokes): @tl3M
Part 2 (Reynolds Number): @ruwY
Part 3 (River Water): @zC6Y

[PsychoticusRex]

In 15 min he described the relationship and terms in the Reynolds equations and general fluid dynamics better than my professor did in an entire series of semesters at university.

[alinpopa]

16:30 "But unfortunately we live in a turbulent world, and we don't understand turbulence"

damn, that was deep

[Scum]

> "We can literally time travel with low Reynolds Number"
"Pff what the hell are you talking about"
> Unmixes dye in syrup
Convulsing on the floor, foaming at the mouth

[joshuakahky]

As a chemical engineer, this is giving me Vietnam-style flashbacks of junior year

[Jodabomb]

For the record, since this wasn't explained well in the video: the bit that makes NS nonlinear is not the fact that it is time-dependent. Many linear equations include time-dependence, like the wave equation, Schrödinger's equation, the heat equation…
The reason NS is nonlinear is because the time derivative is a special time derivative called a material derivative, and it includes an extra term which is not written for compactness. That is why the derivative is written as Du/Dt instead of the standard du/dt; it's actually shorthand for Du/Dt = du/dt + v•∇v.

[elementalsheep]

This guy seems like the James Grime of engineering mechanics.

[ShaneClough]

Love Toms energy and enthusiasm he has for his area of study. Definitely a welcome addition to the channel!

[jannegrey]

Navier-Stokes For The Win!
And Mr. Crawford's enthusiasm is infectious.

[arielvinda]

I love how mathematicians (at least the ones shown in this channel) have this everlasting awe and happiness about the subject

[brightbyte]

"Big whirls have little whirls,
That feed on their velocity;
And little whirls have lesser whirls,
And so on to viscosity."

[akshayhere]

I'm just so happy a channel like this has subscribers in the millions.

[micahphilson]

That Smarter Every Day experiment was incredible before, but now it blew my mind seeing it in this context!

[nicklewry]

As someone currently in a Fluid Dynamics course... this was incredible. You gave me an entirely new, and very valuable perspective. Thank you.

[jamesdong]

I always imagined Brady more like a passive observer, but now I realise that he actually asks relevant and important questions and contributes to a successful explanation

[diarya]

This is so much more fun to watch as an engineering student

[antivanti]

"I am an old man now, and when I die and go to heaven there are two matters on which I hope for enlightenment. One is quantum electrodynamics, and the other is the turbulent motion of fluids. And about the former I am rather optimistic."
- Horace Lamb

[adamgray]

Low Reynolds numbers: Exist
2nd law of thermodynamics: *"Now this is an Avengers level threat"*

[nousefulness]

As a meteorology major it's always great when they discuss thermodynamics or fluid mechanics on the channel

[Lena-rivb]

I was so frustrated about fluid dynamics, so I came to Numberphile. Not only did I gained insight, but I am now sincerely interested in fluid dynamics. Your energy and love for this topic just took me. Thanks so much you made my day.