Transcription
[Music] welcome to the first video in fluid mechanics. So my name is Brendan McDonald, and I'm a professor in mechanical engineering at Ontario Tech University, which is located in Oshawa, Canada.
So I've been teaching fluid mechanics since 2015 at Ontario Tech University. And in mechanical engineering, we offer this as a second-year course, but it can show up as a course in a number of different years and a number of different disciplines, things like physics or other engineering branches. And so this fluid mechanics course is broadly applicable then over a lot of different areas.
So when this course is offered at Ontario Tech, we'll list two prerequisites for this course. And prerequisites are just some courses that we'd like you to have taken before taking this class to make sure you have some of the background information that's necessary to be able to do the material in this course. So the first one we list is calculus, and the second one is physics. And I wouldn't worry too much if you haven't taken either of those courses because when I'm solving problems and doing examples in this class, I tend to go step by step and explain things really in depth.
I would say for calculus, the most important thing is that you're familiar with integrals, what they are, how to solve them. Same thing with derivatives. You know what a derivative is and how to solve that. And when it comes to physics, we're just looking at do you have a basic understanding of of how to do force balances? What are forces? Vectors? Force of gravity, for example, would be mass times g, which is the acceleration due to gravity. Those sorts of things. That's the background information that you'll need to know for this course. Otherwise, everything that you need to know for this course, I'll be covering as we go through these videos.
So in this video, we're going to talk about what the course is about, what are the different kinds of things you're going to learn in this course, and we're going to connect that with the applications. So how the materials applicable. And then we're also going to look at what is it that you will be able to do after you've completed this course. So in terms of things you can design, calculations you can do, we're going to look specifically at what the expectations are in terms of what you'll learn once this course is finished.
Now, also to make sure that you're really learning the material that I cover in this course, I think it's really important to have effective learning strategies. Now, some of my favorite are summarized really well by Richard Feynman. So he's passed away now, but there's a Twitter account that features some of his best quotes. And so this one that I'm showing here focuses on an excellent learning strategy.
So the first point, continually ask why. So as I present this material, I'm gonna raise it in a way where we really deeply understand what's going on. So as you watch these videos, continually ask why and see if you can come up with the answer.
The second point, I'll often get asked by my students, how do I know that I understand it? How do I know I really learned it well? Point number two here by Feynman says, when you learn something, learn it to where you can explain it to a child. So if you're questioning whether or not you understand the material, just imagine yourself explaining it in very simple terms, and that'll give you an idea of whether or not you really understand it.
Number three, and this, I think, is possibly the most important here. Instead of arbitrarily memorizing things, look for the explanation that makes it obvious. So this is something to keep in mind as you go through these fluid mechanics videos because there's a tendency to want to memorize. If I'm solving an example or explaining something, people always want to memorize that. But actually, a much better strategy is to look for the explanation that makes it obvious. This also helps you retain it, right? So if you memorize it, that can go away. But if you understand it, if you have the deeper explanation, then you're more likely to retain it. But also, that carries forward into all the other courses and all the other things you're going to learn. So definitely, as you watch, specifically solving problems, make sure you're not just trying to memorize how I solved it, but you're looking for the explanation that shows you how to solve it so you can solve all the different types of problems that arise.
This is another great one, and this is something I really like to focus on. So when learning, students should be made to doubt, to think, to communicate, to question, and to learn from their mistakes. And most importantly, have fun in their learning. I think I'm lucky that I get to teach fluid mechanics because it's one of the funnest subjects out there, and I think you'll see as we go through this video is what I mean. So as you're going through this, always keep in mind that you should be questioning the material that's presented. So you should be able to doubt and to question what's there, and that's a healthy mindset to go through as we cover this material.
And finally, in terms of education, it's a great quote by Aristotle here. Educating the mind without educating the heart is no education at all. And I think that really speaks to the fact that you, there's a certain level of expectation you should have that you should be enjoying this material, especially fluid mechanics, because it's such cool stuff. So as I go through this, I really want to show you how awesome this material is, how fun it is, to make sure that you're really inspired about it, that you can see what we can do with fluid mechanics, how powerful it is, but also how fun it is, and what incredible designs we can make with it. So that's another big part of what we're going to be focusing on in these fluid mechanics videos.
Okay, so let's first talk about fluid mechanics. What is fluid mechanics? What do those words actually mean? I think there's a lot of misconceptions about this. I think when people come into a fluid mechanics course, there's an idea that they're going to learn about how liquids flow. So we're going to look at piping systems and things like that, and we want to know how do we get fluids to go from one place to another. Now, that is a small component of what we do in fluid mechanics, but that's actually a very small percentage of what we're going to be looking at in this course.
So when we look at those words, we look at fluids. That actually refers to things that flow. We'll look at a more precise mathematical definition in the following video, but for now, we could just say things that flow. So it's not just liquids, then it's gases as well. And you'll see a lot of the applications we're going to talk about in this course is actually gases or air that's responsible for the second component, the mechanics. So the mechanics means forces. It's the interaction of forces. So in a lot of cases, we're going to look at how air interacts with different objects and exerts forces on them, right? And so that's what this course is about. Fluid mechanics: things that flow and the forces that they exert on their surroundings.
I think there's another common misconception about fluid mechanics as well, and that is that it's outdated. But this couldn't be further from the truth. When you look at companies like SpaceX developing rockets or aircraft drones, some of the most cutting-edge fields rely heavily on fluid mechanics. And so fluid mechanics are in high demand right now, and this field is actually quite cutting edge. So you'll see through the course of these videos, the applications we look at are going to be very relevant, very advanced technologies.
Okay, so let's go through some examples of fluid mechanics then. So firstly, let's think about a plane. Now, when a plane takes off, as it immediately lifts into the air, okay, what is touching that aircraft? Right? It's not actually touching the ground anymore. It's not touching anything solid. But we know this aircraft right now is moving upwards and it's being pushed forwards. So the forces, there's tremendous forces being exerted on this aircraft right now. Well, the only thing the aircraft is touching is the air that's surrounding it. So this air surrounding the aircraft must be responsible for these forces. Well, that is a classic example of fluid mechanics because you have the fluid, the air, and then you have the forces. The forces that are actually so high, they're actually lifting this aircraft up into the air and propelling it forward.
Okay, let's do another example. So rockets. As a rocket lifts up into the air, again, it's not actually touching the ground. So the forces that are exerted to blast this rocket into outer space must be coming from the fluids. So we have in this case, the air that's surrounding it, but also there's all the exhaust that's exiting out of the bottom of the aircraft that's responsible for propelling it upwards. And that's something else we're going to focus on in this course.
Next example is racing cars. So let's say you think about an F1 car. As an F1 car travels around the track, to move forward, it actually has to carve through the air that's surrounding it. And there's a classic fluid mechanics problem because as it moves through that air, the air is restricting it from moving forward. So we look at the force, it's actually drag caused by the air around that race car. And so that's something we're going to look at in more detail as well. We can also use those forces. We can use the air surrounding it to actually push the vehicle down against the track. And when we create that downforce, right, it can actually give us more traction in racing. So it's another example of a classic fluid mechanics problem that we're going to be looking at.
Another example is dams or turbines. And these are actually static forces that are exerted by a large reservoir of liquid. And we can take those forces and convert them into electricity, for example. So that's another example of what we'll be looking at in this course.
Okay, and one final example is we could talk about baseball pitches. So as the baseball moves from the pitcher's hand towards the plate, the ball is moving through the air. So again, we have the challenge that the ball has to carve through the air, just like the race car did. But we can also use these forces. So one way we could do that is the spin on the baseball. So what we'll look at in this course is how you can spin the baseball in different ways, and so you can exert different forces from that air it's moving through to cause it to move in different directions.
Okay, so those are just a few examples of the types of things we'll be learning about in fluid mechanics.
Okay, so now we said we'd talk about what is it that you'll be able to do after this course is complete. So I like to look at it in two different ways. You develop an understanding which helps you come up with designs, right, or make innovative technology. And then you also have the calculations, right, where you need to actually figure out the numbers to make the technology work. And so again, I'll go through a few examples of how we can split between this understanding and these calculations.
So we're going to talk about using dams. When we talk about a dam, when it comes to understanding, we want to know why, why do we use a dam? Right? What happens if there's a big reservoir? These are all things we're going to develop on the understanding side of things. And then when we look at calculations, we're going to want to be able to calculate what are the pressures, what are the forces associated with a certain depth of reservoir behind this dam.
Okay, when we talk about rockets, for example, on the understanding side of things, we might be wondering, what is it that actually makes this rocket move? Why is it moving? What's responsible for that? And then on the calculation side of things, we might want to say, okay, so what's the speed of the fluid exiting the rocket that's going to generate the lift force that we need to launch it into outer space? Right?
So we'll look at scaling as well. When we talk about scaling, we're going to look at making small-scale models, right? So, you know, designers do this sometimes and test them in wind tunnels. And so we're going to look at why, why do we need to make scale models? What are things we need to consider when we're making these smaller scale models of a real-world object? And then in the calculation side of things, we're going to look at things like, okay, so the forces you measure in the wind tunnel on a small-scale model, what would the force actually be on the real full-size model? Right? So an example of understanding again, coupled with calculation.
Okay, so we'll look at pipe flow as well. And the understanding, it might be, what causes there to be losses in a piping system? How can we mitigate these losses? So on the calculation side of things, we might look at how do we calculate these losses? How do we figure out what the losses are? How do we size a pump that might account for these losses?
Final example. Now, in looking at understanding versus calculation, we can talk about race cars again, right? So when you're looking at the design of race cars or vehicles more generally, we might ask ourselves, so what are the forces, right, that we can use on this vehicle to make things like downforce? Why do we even need downforce? How do we reduce drag? What's the benefit of reducing drag? And then on calculation, it's specific numbers. So if we reduce the drag, how much fuel can we save? What's the reduction in forces? Right? How much downforce do we actually generate, right, by using certain objects like wings? And so we'll determine values then of the lift force and the drag forces associated with certain vehicle designs.
Okay, so a summary of this video is we talked about what fluid mechanics is, right? So we're going to look at fluids and the forces of the different things they interact with. What you're going to be able to do when you're finished the course in terms of understanding and calculation. And we went through a number of examples, just a few examples we'll cover more in the course of the videos, but these are examples so we have an understanding of what it is this course is going to address, what it is this course is going to do for us, and what we'll be able to do once we're finished this course.
So in the next video, we're going to start to look at a few more technical things. We're going to look at some basic definitions, and then we're going to look at some more fundamental concepts. So these are the things we're going to build on throughout the rest of the course, and so this is going to be the foundation of our understanding.
Okay, thanks for watching.