17.4.2. Aerodynamics in Sports

Good morning, let us have a today class on drag and lift which is the last class of this course okay. This is lecture number 36 and drag and lift. I think discussion of the drag and lift I started from the lecture number 2 where we illustrated how we can estimate it what will be the drag and lift forces of the towers. The And also we talk about this how the bars drag and lift forces in linear momentum equations.

In this section, the instructor introduces the concept of drag and lift, relating it to the overall aerodynamics involved in sports. Drag and lift are aerodynamic forces that affect the performance of athletes using various sports equipment, such as bicycles or swimming gear. From previous lectures, the instructor has laid the groundwork on how to estimate these forces and their relevance to real-life scenarios in sports. Understanding drag and lift is crucial for optimizing performance, as these forces can significantly impact speeds and overall efficiency in competitive sports.

Imagine a cyclist racing against others in the Olympics. Their position, clothing, and bicycle design all affect how air flows around them. By minimizing drag, they can go faster with the same amount of effort. This is akin to how a streamlined car is designed to reduce air resistance and improve fuel efficiency.

So if you look it that way I am not going more detail I again I am to encourage you just look it the very good illustrations are there and in the book of Sinzel-Cembala which gives you a lot of interest on the fluid mechanics if you look at the illustrations what is provided in Sinzel-Cembala book.

The instructor emphasizes the importance of understanding drag and encourages students to explore visual resources, such as illustrations from the textbook by Sinzel-Cembala. These visuals can help clarify complex fluid mechanics principles more comprehensively. The foundational knowledge of drag characteristics is essential for athletes who want to optimize their performance by reducing the air resistance they encounter while competing.

Think about how athletes like runners or swimmers wear tight-fitting clothing. This gear is designed to minimize drag from air or water, allowing them to move more swiftly and efficiently. Without such designs, they would struggle more against opposing forces while performing.

When you have a cyclist driving a bicycles if you can look at recent Olympics and all if you see these persons lean seat okay as to reduce the drag forces it just leans it as going with so the basically minimizing the drag force so it leans up depending upon the speeds.

Athletes, particularly cyclists, exploit their body position to decrease drag while racing. By leaning forward or adopting a streamlined posture, cyclists can reduce the frontal area exposed to wind, thus lowering the drag force significantly. The instructor notes that during competitions, even small adjustments in posture can have substantial impacts on performance due to the physics of drag and lift.

Consider how a diver enters the water: they propel themselves downward, then tuck their body to minimize resistance when they hit the water. Similarly, cyclists adjust their bodies to cut through the air efficiently, showcasing a fundamental principle of aerodynamics at work.

Most often we define the drag force is a functions of half rho v square multiplied with a Cd this is called coefficients of drag into A is the frontal area.

The drag force can be mathematically represented by the equation F_d = (1/2) * ρ * v² * C_d * A. Here, ρ is the fluid density, v is the velocity of the object, C_d is the drag coefficient (a dimensionless value), and A is the frontal area of the object. This equation highlights how different factors contribute to the overall drag force, and understanding each component is crucial for athletes and engineers aiming to reduce drag in their designs and practices.

Imagine you are trying to walk through water. If you wear a bulky wetsuit (larger frontal area), it feels much harder than if you wore a sleek swimsuit. Similarly, the drag coefficient changes based on the shape and smoothness of your body (or bicycle) interacting with the water (or air). Athletes meticulously design their gear to minimize A, C_d, and enhance performance.

So if you look at the drag okay which is a it is a very simple definitions as you can understand it that is a force flowing fluid exerted on a body in the flow direction is called the drag okay. Just normal to that components we can say that is that lift okay.

The lift force is defined as the component of the aerodynamic force that acts perpendicular to the relative motion of the object through a fluid. While drag opposes the motion, lift helps to elevate or support the object against gravity, making it possible for aircraft, athletes, and even swimming strokes to perform optimally in their respective fields. The understanding of both drag and lift is crucial for a comprehensive view of fluid dynamics in sports.

When an airplane takes off, its wings are designed to create lift. Similarly, when a swimmer uses the right stroke, they can create lift that helps them glide through water more effectively, much like how a bird takes flight by spreading its wings.

So if you look it for the circular case you have a frontal area d into L but in case of a rectangular case in the B so you know the frontal area you know this Cd value you know the design velocity you can always compute it what will be the drag force is very simple thing.

Athletes and engineers can calculate expected drag and lift forces using parameters like frontal area and drag coefficient specific to their sport or equipment design. For circular and rectangular shapes, the calculation simplifies further since formulas relate directly to their dimensions and projective areas faced by the fluid. Utilizing these calculations allows for more efficient designs in sports equipment.

Think of how car manufacturers design cars with different shapes to lower air resistance. In sports, similar strategies are employed—like the difference between a classic Sledge and a modern, streamlined bob sled. The latter is designed to minimize drag, allowing for faster runs and better control.

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