Controlling Turbulence and Evolution: How Engineers Overcome Uncertainty
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- เผยแพร่เมื่อ 24 มิ.ย. 2024
- Two examples of how engineers solve problems before they have scientific certainty: How they control whether or not fluid flow is smooth or turbulent, and how they engineer useful enzymes.
Learn More: Companion Book
Explore the ideas in this video series further with its companion book: The Things We Make: The Unknown History of Invention from Cathedrals to Soda Cans (ISBN 978-1728215754)
www.amazon.com/Things-We-Make...
Other videos in this series
Episode 1: Building a Cathedral without Science or Mathematics: The Engineering Method Explained • Building a Cathedral w...
Episode 3: The Steam Turbine: The Surprising Relationship of Engineering & Science • The Steam Turbine: The...
Episode 4: The Microwave Oven Magnetron: What an Engineer Means by “Best” • The Microwave Oven Mag...
Video Summary
00:00 Titles
00:07 Laminar and Turbulent Flow
To illustrate how engineers work their way around uncertainty Bill introduces one of the most complex phenomena in nature yet one of utmost importance to engineers: the transition from laminar to turbulent flow. To illustrate these types of flow he examines the smoke rising from burning incense pointing out that the smoke near the incense flows smoothly (laminar flow) and further away becomes violently swirls (turbulent flow).
00:51 Engineering & Turbulence
He notes that to this day a fundamental understanding of when that transition from laminar to turbulent flow occurs puzzles scientists, yet, engineers must know when the transition occurs to control which type of flow occurs. Of prime importance is the smooth, laminar flow of air over an aircraft wing. Yet, without a fundamental scientific understanding of how to achieve that laminar flow we have flown across the Atlantic Ocean routinely since the first commercial passenger flights in 1939.
1:23 Reynolds’s Apparatus
Although twenty-first century science cannot fully understand turbulence, a nineteenth-century engineering professor, Osborne Reynolds, built an apparatus to find a formula used by engineers to predict the transition from laminar to turbulent flow. Reynolds learned that a) below a particular flow rate no turbulence occurs, b) that the transition occurs abruptly, and c) that there is an upper limit to the flow rate above which smooth flow cannot be sustained.
3:10 Reynolds’s Explanation
To understand this behavior Reynolds compared the flow of water to a military troop. He reasoned that the orderliness of marching troops depends on three characteristics: speed, the number of soldiers in the troop, and discipline. The speed of the troop corresponds to the flow rate of the fluid, and the size of the troop to the diameter of the pipe. And the “discipline” is something called viscosity. It’s the resistance to flow.
3:51 Viscosity: Water vs Honey
To understand viscosity, Bill compares the different rates of flow for water and honey: the water flows readily, while higher viscosity honey flows slowly.
4:04 Reynolds’s Number
Reynolds gathered three characteristic of fluid flow - the diameter of the pipe, the velocity of the fluid’s flow, and its viscosity - into a single relationship: The diameter times the velocity divided by the viscosity. He observed that when this combination of variables was less than about 2,100 the flow was laminar and above that value the flow could became turbulent.
5:16 Technological Importance of Flow
With this relationship engineers could know what to change to achieve laminar or turbulent flow. Bill mentions three designs where engineers want to control the type of flow: mixing pharmaceuticals, cooling steel, and directing the flow of air around a truck.
5:51 Science vs Engineering
Reynolds’s approach doesn’t describe turbulence at a molecular level, his description was phenomenological (that is, a description of what is observed). This difference underlines the striking difference between science and engineering: the scientific method strives to reveal truths about the universe, while the engineering method seeks solutions to real-world problems.
6:10 Scientific Breakthroughs Only Change Boundaries
We might think that today’s science would subsumes all of engineering. Yet scientific breakthroughs never remove the need for engineering: Humankind developed the engineering method to reach beyond codified scientific knowledge. Instead, the advance of science only pushes out the boundary between the certain and uncertain, and so resets the boundary where engineers work.
6:35 Directed Evolution
To illustrate that even today engineers step beyond scientific certainty, Bill tells the story of Nobel Laureate Frances Arnold’s evolution of enzymes that can be used under the harsh conditions of industrial use.
12:01 Next Video
Bill mentions that in the next video he will explore the relationship of engineering to science.
12:10 End Titles - วิทยาศาสตร์และเทคโนโลยี
(Crashes through door, stumbles into room). Did someone say LAMINAR FLOW?
😂 glad you heard and came
I was scrolling through the comments just to see if you were going to chime in.
And here you are. 😁
Certified Destin moment
OH YEAH! Got your smooth FLOW right here!
Destin!
Ah. The David Attenborough of the engineering world. Could listen to you for hours. 😊
That's quite the compliment ... and I hope I can work into my 90s!
@@engineerguyvideo Bill, thank you so much for doing these videos. I've missed them dearly. I'm very much liking this series as I never thought of the engineering method, but what you're saying makes so much sense. Brilliant series. Once again, thank you!
@@engineerguyvideo Bill you have a tone and cadence of voice that just keeps your attention.
I was in public radio for this … did 200 pieces … in radio voice and words are all you have!
@@engineerguyvideo We are forever grateful for your contributions ❤
I've been studying engineering for 2 years now and at no point was this distinction between engineering and science made.
Here I was, thinking of engineering as an application of the scientific method to real world problems. I am both frustrated with myself and amazed at how well these past two episodes have portrayed engineering in a new and much more interesting light.
Engineers tend to overvalue their knowledge and think they are scientists.
@@itheuserfirst3186 I think every profession has this to some degree. People in general like to hold themselves in high esteem, thats only occasionally a bad thing.
An engineer can be a scientist and use the scientific method to find solutions to their problems. This and the earlier video have not so much altered my view of what an engineer does but rather expanded it.
@@itheuserfirst3186Scientists tend to get tomorrow to explain what an engineer had to do yesterday lol. Seriously though pure and applied both have value.
Science is the endeavor to understand reality using the scientific method. Engineering is the endeavor to apply that knowledge to improve life.
@@billschlafly4107 Yeah, that's the whole thing with this series. Scientists research things, engineers apply knowledge. Both are valuable resources that improve our lives daily.
Even in situations where full scientific understanding _IS_ something we have, reality is messy. Just because you fully understand a process doesn't mean it's _easy_ to control it. The machinery to do the job perfectly may be far too expensive to construct, maintain, or train operators to use. So instead we engineer something that's _good enough,_ because it's cheaper than perfection, and we don't actually need perfection.
Spot on
This reminds me of "all models are wrong, but some are useful" (George Box).
@@riveradam Yep, even if you have all the data to generate a perfectly correct model of some situation, a slightly less correct model will probably calculate much faster. You don't need a weather model that predicts tomorrow perfectly, but takes a decade to run. By the time it delivers results you could just look at historical data.
Chase perfection, achieve excellence
@@AverageAlien Just make sure you're not so busy chasing perfection that you don't notice you've achieved excellence.
glad you found time to make more videos. each one of your episodes is a true joy to watch and learn from.
Strikes me that a lot of what’s happening in the field of Machine Learning today is not science but engineering. As with the discovery of the formula for what makes turbulent flow, it might take decades more to understand the principles behind it.
I was struck by that similarity as well. No need to discover every possibility, just keep expanding the ones that work best.
Machine learning is a field of computer science.
... Which is a total misnomer. Since it's not about computers - those are the subject of computer engineers, who are electrical engineers. And it's also not a science, since it doesn't reveal fundamental truths of nature, it's a field of engineering. It's data processing engineering.
Isn't this what "software engineering" is supposed to be about?
@@EebstertheGreat Software engineering is about architectural decisions in software design. Computer science is about algorithmic decisions in software design. So we're in the domain of computer science rather than software engineering. Of course computer science is not a science but I've said that before.
@@SianaGearz Computer science is a science sort of like statistics or economics is a science. It's largely formal and theoretical, but I don't think that disqualifies it from science status.
I don't think fiddling with an AI is really computer science at all, though.
I just took a class called “scientific computing”, which funnily enough focuses entirely on approximating solutions to real world problems. In the class we learned how to evaluate a bunch of equations like optimization problems (essentially solving for x when an equation is traditionally impossible), and things like approximating the solution to second and n-order systems of differential equations which model different real-life systems. Although the pure math hasn’t quite gotten where it’d need to be in order to do these things, we can approximate a solution to them with nearly perfect accuracy using computing techniques developed long before computers ever were, by mathematicians like Euler and Newton. Thanks for coming back Bill!
I've always shied away from using the terms "audio engineer" or "computer engineer" to describe the jobs I do, but that's come from a misunderstanding of what an engineer is or what makes an engineer. This new series helps me better understand that I have been using the engineering principal all along and don't need to be a lab-coat wearing scientist to be an engineer. Looks like I've got a new book to buy. Thanks, Bill, and welcome back!
Do you remember a cartoon called Dexter's Lab? His catchphrase was "For Science!" I would shout back "no, what you're doing is *engineering*!" Such is the propagation of misunderstanding in our society.
So glad you're back. I got your book on the R101 (both audio and paper) had have referred to it often as an example of using completely non-intuitive solutions for problems (like the use of bovine intestinal tissue to make hydrogen gas bags).
Another use of Reynolds number, is that it makes wind tunnel testing of scale models possible. The air flowing over a small model will act quite a bit differently than on a full size aircraft at the same speed, so aero-engineers make sure to test at the same Reynolds number (Rn) to take into account the differences in size, which usually means running the air past at higher speeds.
This only works up until the transonic region, though (Rn is different at supersonic speeds), so NASA devised a clever way of increasing Rn other than the speed of the airstream. At their Ames Research Center, they build a pressurized wind tunnel where the whole thing is pumped up to two atmospheres. To have access to the test subjects without venting the whole tunnel (which takes several days to pressurize), they built the world's largest ball valve with the test section being the hole in the center. When they want to access the test subject, they rotate the ball 90° so that the center faces outwards and the rest of the tunnel stays sealed.
I'm so happy that you're back making videos again. Excited to watch more!
Thank you for this. I work in an engineering department where our needs are outpacing our certainty. I have felt guilty pushing for us to catalog our rules of thumb instead of waiting for guidance or more data. I feel much better about it now.
Engineering is just brute forcing nature to my will regardless of how the science works. I'd never thought of the relationship between those two methods like that... Mind blown, thx Bill.
I enjoy your videos, but I don't understand how what Reynolds did was not science. He did various tests and recorded the results to build a theory. Maybe he didn't dig down to find out 'why' and only dealt with the 'how', but I don't believe that forgoes it being a scientific study. As other commenters have mentioned, I'd be curious to know how you define the scientific method.
I ❤ your channel and presenting style! I noticed the slower pace here too, an improvement for me - easier to digest. Thank you sir.
Dude, I've been a fan ever since you stepped into the limelight with a a shiny aluminum can. I'm bummed whenever you don't post for a few years, and I'm happy to see you back. I sure wish you'd just become a full time TH-camr.
I will always be slow but I’d like to be continuous!
Hi Bill, Glad you're back here, here !
Just a quick side note: 4 min 50 to 5 min 20 is correct, but very confusing, because we normally work with a fixed flow rate (m³/s) and not a fixed velocity (m/s). This means that normally, one increases the diameters to get back in laminar flow, because the increased diameter drops the velocity squared. Doubling the diameter, means dividing the velocity by 4, effectively halving the Reynolds number with a fixed flow rate.
Thanks for analyzing that and noticing the fixed velocity! I was super confused until I saw this comment as I hadn't noticed the fixed velocity instead of the flow rate and like you said was saying in my head doesn't increase in diameter lower the velocity and hence turbulence..
Thank you, that was what was bordering me, did not think of a fixed v...
(Does nobody think of the poor pump?!)
Wait. This is daily series!?!?
Feels like Christmast!
I'm an immortal highlander who has been studying liquid flows since 530BC (Heraclitus stole the whole river thing from me) & doing flow rate calculus for about 250 years, and I learned more from this video than during my entire cursed existence.
Bill, you're by far my favorite educational channel on youtube. Happy to have you back. Cheers!
I'm so happy you're back!!
In the early 90s when I was still a child, hearing about enzymes in laundry detergents being the hot new thing. Even as a child I found the idea amazing, how enzymes were integrated in order to "digest" stains, so to speak. That's how I imagined it. It's great to hear the context around this, and learn about Frances Arnold and her excellent method.
just a fun little fact, so it's estimated that the number of atoms in the observable universe is about 10 to the 81st. so 20 to the 270 is uh, yeah.
What a treat to have not just one, but 3 new Engineerguy videos to enjoy! Thanks for posting these Bill, it's always a treat when a new one comes out :)
THANK YOU FOR YOUR RETURN! I wish I could convey properly in a such a comment my gratitude for the work you do here.
I have missed this channel so much. Glad to see more content from you, Bill!
Salute to this guy.... TheEngineerGuy
I have been watching your videos since the first semester of college and on the 20th of this month I will be a chemical engineer like you sir! Thanks for sharing your knowledge.
I love this video. I would like to add that enzymes, which are proteins that are biologically engineered catalysts, are not only sensitive to temperature, but also so many other factors implied by Frances Arnold's brilliant yet simple experiments...acidity, salinity, and probably more things but it's been a while since my biochemistry classes. (Entropy?) I would also like to add that First Principles is a constantly evolving/expanding foundation, so eventually our First Principles of solvent and biological solute will one day be able to explain interaction amongst players. But Engineers will have moved far beyond the need for this by then :)
Wonderfull to see you again here on yt!
This video is excellent! A 12 minute masterclass!!! Thanks, Professor!
Great series so far - fascinating to see the engineering method conceived as being so independent from the scientific method - quite convincing
Being an aerospace engineer working primarily in aerodynamics, it’s one of the most captivating parts of the field knowing you’re working around something that is not fully understood and cannot be perfectly modeled based on equations that are currently impossible to solve.
This example of enzymes reminds me of Gregory Mendel and how people in early eras somewhat understood inhereted traits without knowing about genes just by planting and raising animals.
So glad to see you back on TH-cam!!! Smiles all around!
yay! you're back. Very excited!!!
It’s about time you posted again! I have been waiting for years! Your videos are some of the best!
Wait what? another one, what a treat!
Holy cow! It's good to see you're uploading again! I'm an Engineer now! Thank you, I used to watch your videos when I was working retail and they gave me hope.
SO GLAD this channel is back!
Holy moly! So glad you are back!!!
Absolutely lovely as always, Bill! Fascinating perspective
The world missed you! Thx for every video.
Welcome back! You have been missed! I hope all is well with you and yours.
Wow, he's back. Awesome👍
Thanks Bill! Another excellent video.
He is BACK!
Great to see you back on youtube, Bill. Love your videos.
It's awesome that you're making videos again!
Well glad you are back and giving some real purpose to TH-cam. Thanks Bill!!
Excited to see new videos on the channel. These videos embody in educational content a crowning feature of quality engineering: impeccable simplicity.
The GOAT is back! Gonna have to come check this out after I get off of work.
so glad you are posting more videos. your way of teaching makes learning such a treat!
Thanks dad, so great to see you back on the platform, creating content
I was not expecti g this so soon after the last one
I missed these videos. Welcome back!
Glad to see you back Bill, congratulations for another great video!
Thank you
Been waiting for a new one for a while
So glad to have you back❤️
I wish you were my teacher at school! You are so easy to follow and understand.
Thanks for the amazing content.
Great video! The task of a scientist is to understand the problem to the core. The task of the engineer is to make it work even if the scientists don't fully understand it.
Thanks for making subtitles!
It's great that you are making videos again! Great video!
I love this channel so much. Great to see these recent videos Bill. Thank you for excellent content.
Other video?! SO SOON!!?! This is a real treat!
WOOHOO! You're back!
Wonderful stuff! Welcome back to youtube.
As a scientist (in training) I agree fully with the ideas in this video. The real world is so incredibly complex that it would be hubris to assume we could ever calculate the world from first principles.
That was quick. 2 videos back to back! Awesome. Happy me now
welcome back, my dude!!
Awesome video, I was excited to find a video for the second day in a row - looking forward to the next ones too!
Glad you're back Bill.
Spread out those videos! Haven't even had time to watch the one from yesterday!
omg, you're alive! This is awesome
I saw your aluminum can video so so many years ago. It's good to see your videos again, you make it really simple for any of us to understand. Thank you engineering guy.
Thank you for making more content! You're awesome!
So glad you are back :)
Fascinating as always. People like Frances Arnold should be household names by now, and our kids should grow up hearing their stories. And once again, thank you very very much for explaining these concepts.
ayyyyy, welcome back bud.
Fantastic series! Thank you for this!!
So glad to see there is an audiobook, can't wait to listen on a long drive
It’s not read by me …
For any science to make the leap from hypothesis to theory a scientist will always be faced with the practical 'real world problems' of a suitable experiment, which in most cases necessitates the involvement of engineering and in many of those cases professional engineers. Outside of the mathematics in science, and rote application in engineering, the two areas are inextricably linked.
E.g. Without context I would have thought Reynolds experiment, equation and numbers _were_ science. It may not get to deeper aspects, but most laws of physics (which this is similar to) also dont. It may not be of the highest precision, but all science is only ever proven within error bars. Ultimately his experiment seems indistinguishable from many scientific experiments going on the world over; It seems that whether this is engineering or science is primarily depending on whether the person looking at it is an engineer or a scientist.
Reynolds number is not a scientific discovery or really even close to a physical law because it does not actually mathematically define or describe the behavior of a flow. It is instead a dimensionless number that is used to try and predict it. If someone were to simply say that a point in a flow has a Reynolds number of 1000, that doesn't really mean anything on its own, there is no Reynolds number that equates to turbulent flow for all systems, so it really has no relevance at all to science. Its utility pertains only to engineering as a similarity parameter.
Suppose you had an airplane designed to fly at 200 mph and an altitude of 12,000 feet. If you wanted to observe the flow behavior at these conditions on a scale model in a wind tunnel, you would design the wind tunnel test such that the scale model has the same Reynolds number as the full size plane in the flight conditions (rather than matching atmospheric conditions and velocity). It is an application developed to overcome/test the problem rather than to actually understand it.
I agree that Reynolds' experiment is much closer to science than engineering. As alluded to in the reply below by Daniel Horton, the turbulent transition mentioned above is for the limited case for flow in a smooth tube. I think a different fluid mechanics example would have been more apropos to the series, perhaps dealing with sailing ships. But fluid mechanics is a field that has been rather difficult to apply using only heuristics.
@@dhorto27 The Reynolds number is effectively the ratio of the inertia stresses to the viscous stresses in the flow. Turbulent flow (high Re) is where the inertia stresses (kinetic energy) dominate over the friction/viscous stresses. So there is a physical meaning, though not a precise physical law.
@@euanthomas3423 Yes this is true. What I was trying to express is how it’s lack of units as a ratio means there isn’t a concrete number where the flow becomes turbulent, which in my mind would make it a scientific discovery, rather than just an engineering heuristic. Like if you were given a length of 6 feet without context, this has physical meaning because feet are a defined unit of distance. If someone just gave you a Reynolds number of 2000, yes it’s the ratio of inertial and viscous effects, but as far as the flow being turbulent/laminar is concerned, more context and information is needed before you can understand what the flow looks like. You can visualize a foot, but you can’t visualize a dimensionless quantity.
Best channel on TH-cam is back!!
New to this channel. Loving the content covered and perhaps even more the 'fireside' style in which it's presented
These feel like coming back home. Reading the book now and loving it!
I'm so happy to see you back, hope you are doing well.
Thanks for another great video, You and Tim Hunkin are my favorite youtube 'engineers.'
Beautiful piece!! Best of the bests. Thank you, Professor Hammack!! I learned something today.
I am in the mentoring phase to other engineers where I work.. I keep your clear, direct and professional presentation methods in mind whenever we talk. Thank you for sharing!
Thank you for your kind words
And in this video, the transition from fluid mechanics to chemistry is still uncertain 🙂
Fascinating! Clear description of the difference between engineering and scientific endeavour, plus great delivery
Another great video. Thanks!
So glad you are still alive
Hi Bill!
Great videos, but something is irking me here. After watching these two, I still don't understand what an engineering method *IS*. Taking Reynolds example, how did he know, which variables to account for, and which were irrelevant (like temperature etc)? Why should they enter the formula with power of +1 or -1 (and not squared, or cubed etc)? Hard for me to believe it was just a guess, because naively it's counter-intuitive that fast-flowing water will result in turbulence. Indeed, if turbulence is a deviation from a "straight" flow, shouldn't faster, stronger flow encourage dye particles to flow straight with it? Reynolds must have understood something about this phenomenon, he didn't just guess the formula.
Same with protein activity. I will grant the idea to test with diluted paint thinner as part of "engineering method", but otherwise the explanation of "employing nature's own ways to find the solution" isn't quite as simple. If have to pass a narrow funnel in the solution space, you're out of luck. Guessing a single mutation will take 19*275=5225 tries. If two or more simultaneous mutations are required, it becomes completely impractical. Nature, on the other hand, employs evolution concurrently in billions and billions of organisms, and thus is able to explore the solution space much more thoroughly. It's hard to believe that Arnold was just lucky to get something working in her first 20 (or however few) tries. There must have been more to it, e.g. understanding how solvent changes protein's conformation or interferes with reaction center configuration. But then I start thinking, wait, isn't it the same as a scientific method? Isolating crucial factors and throwing away everything else to build a model, that's how science works, isn't it?
Sorry for a wall of text!
The main distinction he's making is that the scientific method seeks to understand the mechanisms behind how something works, while the engineering method seeks to use those mechanisms to solve problems but without the need to understand how they intrinsically work.
Like with the enzymes, sciences isn't really sure why they work, while engineering isn't too concerned with the why but only with the way in which they can be applied.
At least for the Reynold's Number you can look up his exact paper where he broke down how he figured out that particular formula with the reasoning behind each part:
"An experimental investigation of the circumstances which determine whether the motion of water shall be direct or sinuous, and of the law of resistance in parallel channels"
The reasoning for choosing the different powers of +1 or -1 comes from mathematics (dimensional analysis) rather than any sort of scientific experimentation. Reynold's number is a non-dimensionalized number (i.e. has no units), which makes it useful in comparing similarity of flows. Reynolds could simply choose the important flow properties (density, velocity, length, viscosity) which have known units, and then create the formula for the non-dimensional number using Buckingham Pi theory.
i love the parallels you could easily draw between the second half of this video and the current stage in machine learning evolution.
ah what a treat, two days in a row. thanks guy.
Wow Engineerguy is back again! One of the best channels on TH-cam. I hope you've been doing well.
Marvelous content.
Always a treat, and I'm enjoying the book.
love how ur recent videos have focused on the science vs engineering misconception of being the same.
Hi Bill! Long time fan of your channel, so glad to see you back!!
One note: I suspect some viewers might be confused when you use the term "scientific method," and it might be worthwhile in your next video to define what you are referring to when you use that term (perhaps this is already planned). As I'm sure you know, the typical "scientific method" is a cyclical process of testing and refining hypotheses through experimentation, which is a process that can presumably be applied to any sort of discovery - including within engineering. I'm not sure that's the scientific method you are intending to illustrate in contrast with your "engineering method," so it might be good to clearly define the concept and how you are using it for this comparison. You could draw the distinction that the scientific method is purely about *observations* of causal realities, as opposed to engineering's practical results; or maybe explain that the "scientific method" you're talking about is not the cyclical process of hypothesis and experimentation itself, but rather the obsession with purely physical, chemical, or mathematical realities. I want you to know I do agree with your conclusions in these videos - an engineer can find a solution without necessarily knowing all the gritty "scientific" details - but in arguments of definition, it's first important to clearly set up the terms being used on either side to prevent confusion.
Wish you the best luck on all your content moving forward, can't wait to see what's next!!!