Hydrodynamics is the study of the motion and forces of flowing fluids, such as water and air, and has applications in sports, engineering, and the natural sciences. The Laser Racer swimsuit, which debuted at the 2008 Beijing Olympics, utilized the principles of hydrodynamics to minimize drag underwater and helped break many records.
In 2008, the swimwear company Speedo developed and introduced a swimsuit using advanced materials and technology called “Laser Racer,” and the term “tech doping” began to be used in the swimming world. The term “laser effect” was coined because 23 of the 25 world records set at the 2008 Beijing Olympics were set by athletes wearing these high-tech swimsuits. Many athletes competed in the “Laser Racer” full-body swimsuit at the Beijing Olympics, and a number of world records were set. This led to the International Swimming Federation banning the use of high-tech swimsuits.
What are the effects of these high-tech swimsuits that have led to these results and controversy? As we know from experience, when a person moves in water, they are resisted by the water. There are three types of resistance: the resistance caused by the water hitting the body (shape resistance), the resistance caused by the water sliding across the body’s surface (surface friction resistance), and the resistance caused by the pressure difference between the front and back of the body (pressure resistance).
To reduce shape drag, you need to make your body hit the water less, which is why people “swim” by lying on their stomachs in the water. Naturally, swimming is faster than walking in the water. In swimming competitions, this doesn’t make much of a difference because athletes swim the same stroke and their physical conditions don’t vary much. This is why athletes train and build their bodies in order to make a small difference.
The problem, however, is surface friction resistance and pressure resistance. In the past, most athletes swam ‘almost naked’, so there wasn”t much difference here either. At best, they tried to reduce friction by grooming their body hair. But with the advent of the full-body swimsuit, the surface of the body was changed to that of a fish. This reduced the friction between the body and the water and also reduced the pressure difference between the front and back of the body, overcoming a previously insurmountable problem.
This long story of a swimsuit and water is a good example of what hydrodynamics is all about. Anything that can flow around us can simply be called a fluid, with water and air being the most common fluids we can feel. Fluid dynamics is the analysis of the phenomena that occur between a fluid and an object, like the one above. In swimming, the swimmer is the object and the water is the fluid. The three resistances mentioned above can exist between any fluid and an object. This is true not only when a swimmer is swimming in water, but also when an airplane flies through the air in the sky, a baseball flies, or even a raindrop falls.
Conversely, the same can apply when an object is stationary and a fluid is flowing. The breeze you feel when you turn on a fan is the same breeze you feel when you ride a motorcycle. Therefore, fluid dynamics is also about analyzing what happens when wind blows through a gap in a building or when river water flows around a bridge pillar. The same is true when objects change slightly. When water flows through a water pipe or wind blows through a tunnel, the same resistance occurs between the object and the fluid. It’s a bit more complicated, but blood flowing through a blood vessel also creates resistance. Analyzing this is also covered in the same area. Fluid mechanics is a field of study that is interested in and analyzes all phenomena that occur between a fluid and an object.
So, how does hydrodynamics analyze these phenomena? There are two main methods, which are divided into two areas: experimental fluids and computational fluids. These two methods are used to measure resistance and observe various other phenomena.
Experimental fluidics is exactly what it sounds like: analyzing the phenomena between a fluid and an object through experiments. Using the swimsuit example again, you would put different swimsuits on a mannequin and observe or measure what happens when it moves in the water. If your goal is to reduce drag, you can use these experiments to choose the swimsuit with the least drag. Of course, it would be impractical to have an expensive mannequin made and dressed in a swimsuit of every material, so it’s important to find ways to experiment with less cost and effort.
Computational fluidics is the use of computers to analyze hydrodynamic phenomena. It is a method of calculating the dynamic properties of objects and fluids by replacing them with equations and numbers. However, it is still limited in its use because it is too complicated to analyze complex phenomena or when the characteristics of the object are not well understood. However, as the performance of computers improves, more and more applications are being developed. Despite these technical limitations, computational fluid dynamics has the advantage of analyzing phenomena at a fraction of the cost of experiments.
Since the world around us is filled with fluids and we live in fluids, virtually any object that moves can be analyzed by fluid dynamics. Of course, since fluids are in motion, even objects that are stationary can be analyzed in this case. So there are a lot of phenomena to analyze in the world that engineers who study fluid dynamics see.
There are so many things to analyze, and if you pick one of them and study it well, you may be able to create new value from it. It can provide the foundation for a technology that can be applied to other technologies, or it can be monetized by companies. In sports, analysis in fluid dynamics has led to such spectacular performance improvements, such as the “laser racer” swimsuit, that it was eventually banned! In the automotive industry, the less drag a car has, the more fuel it can save, and the more money it can make.
Of course, hydrodynamics isn’t the only thing that creates value. It’s how soccer players kick banana kicks, how baseball players throw curveballs, and why sharks have such hard skin. The world is full of interesting and curious things when seen through the eyes of fluid mechanics. Fluid mechanics is the process of studying, analyzing, and solving these questions.
