The ultimate fluid mechanics tier list

Fluids can do really cool things, but which things are the coolest? Soon-to-be-Dr Kat from the University of Bath, studying for a PhD in fluid mechanics, put fluid effects including laminar flow, vortex streets, and the Kaye effect.

What's this based on? Almost entirely just vibes.

Check out Kat on her socials!

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Some stock footage courtesy of Getty.
Edited by Luke Negus.

This guest video from KatDoesMaths on Twitch is about fluid mechanics, which fluid effect is coolest, and ranking fluid mechanics in a tier list. Kat talks about phenomena including vortex sheets, bouncing droplets, viscosity, turbulence, and laminar flow. If you like videos from Stand Up Maths, 3blue1brown, Flammable Maths, Andrew Dotson, Numberphile, and Steve Mould, you'll like this fun video about maths and a tier list of fluid dynamics.

Huge thanks to my supporters on Patreon:
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[ThomasRintoul]

Loved this! Though I'm not sure I can forgive putting the Rayleigh-Taylor instability in D tier. Turbulent flow is cool!!! We don't need analytical solutions!!!

[jhawar-ji]

Laminar Flow in C tier! I have seen everything in my life. My will to live has left my body.

[ibonitog]

I will never forgive you for your Turbulence-F-tier choice!! :D chaotic systems and the mathematical process of (seemingly) random behaviour arising simply from the non-linearity of deterministic systems is so deeply fascinating and beautiful to me!

[nikospud]

Amazing stuff. For the first time I am convinced that Kat is a mathematician and not a physicist based on these rankings. #Justice4Laminar

[juanfelipecespedes]

You would think that a mathematician would put turbulence, the most important unsolved problem in classical physics, up in the tier list due to the challenge of its complexity. #MillenniumProblem

[juanmairal]

Mostly agree but I can't allow Turbulent Flows to be left in the F tier. A problem that scared both Feynman and Heisenberg deserves a much higher position imo. Seriously, as a PhD student of CFD myself I loved the video and I appreciate how a tough topic like fluid dynamics is made very approachable. This is some top tier science communication and I am definately returning to this for inspiration for my next talk.

[MrSam]

I’m happy there was no Fog fiasco in this great tier list. Fog is S tier

[mikefochtman]

Nice stuff. I remember learning about 'Taylor bubbles' when we were studying boiling water in power plants. The vapor formed when boiling water has to travel up the tubes inside where it was heated. Small bubbles with a large amount of liquid flowing wasn't a problem. But as you add more and more heat, the bubbles coalesce and eventually 'fill' most of the tube. Now you have a wholly different flow behavior that impacts the heat transfer with the tube wall.

Fluid flows are so wonderfully complex, even for something as 'simple' as water. :)

[Nartinan]

Fire is arguably another multi-layered fluid phenomenon. Combining interesting fluid dynamics with chemical reactions, phase changes and (somewhat limited) self-sustainability. Considering its beauty and utility, but also the relentless chaos and violence is causes, it's an easy S Tier for me.

Also, I can't believe you put the Crabby Nebula in D Tier.

[dungeonseeker]

Here's an interesting one, in Chemistry there's a thing called the Briggs-Rauscher oscillating reaction, not only does it look kinda gorgeous but I have to imagine there's some funky stuff happening inside the reaction material too.

[charliemw]

As a CFD engineer I see no problem with turbulence, it's easy to work with, just slap a RANS model on top and pretend it's another passive scalar. Turbulence is clearly S tear 😢

[dougdimmedome]

It’s a crime for a mathematically oriented fluid mechanics person to put smoke rings in E tier.

[TheMorris]

I disagreed with almost every pick, but I still loved this video. Great work!

[mudgetheexpendable]

Not that it matters, but I completely agree with your higher placement of the ring bubble on grounds of coolth. Fun video, thank you and Simon for it.

[vblaas]

Suggestion: Some planetary flows could be included, like coriolis effect, saturns hexagon and jupyters towering cloud bands? Awesome video. Rayleigh instability in a water tap should be higher tier for being so commonly overlooked.

[TheOllieJackson]

As someone currently doing their PhD in Vortex Ring dynamics... I think they're neat

[p_mouse]

The thing with laminar flows is not about its simplicity, but how rare pure natural laminar flows are. They barely exist. One tiny bump can ruin your perfect flow completely, some taking the whole thing to the other extreme.

[Respectable_Username]

I love how vibes based the actual rankings are alongside being shown super cool phenomena. Great video! ❤

[pablo_CFO]

I almost die when I saw "Turbulent flow" ranked in the F tier and "Vortex rings" in the E tier... and i understand that this ranking was based on different types of fluid flows rather than specific techniques. However, for me, Lagrangian Coherent Structures represent the most beautiful way of visualizing fluid flows. ❤

[xsnozskwg]

I adore living in an age where I get to see scientists and mathematicians share their interests and studies in such an accessible and fun way. I can't help but feel the call to explore each example in depth and find out even more.

I won't stand for the train slander though.