The Coanda Effect experiment

Believe it or not, scientists are still arguing precisely about what scientific principle should be used to explain why an airplane can fly. One explanation, the Bernoulli Effect, is commonly used to describe the phenomenon of flight. In this experiment, we demonstrate the second explanation – the Coanda Effect.

Light a candle and place it on a table.
Place an oatmeal or salt container in front of the candle.
Blow against the other side of the container (the side opposite from the lit candle). Be sure to keep your mouth even with the flame of the candle.

What is the Coanda Effect?

The Coanda effect is a phenomenon in fluid dynamics where a fluid flowing over a curved surface tends to follow the surface, rather than continuing to flow in a straight line. This effect is named after Romanian physicist Henri Coanda, who was the first to describe it in a scientific context. In this experiment, air acts like a fluid and follows the contour of the round container. When the streams meet on the other side, they combine to blow out the candle.

One of the most common examples of the Coanda effect is the way a stream of water from a faucet or hose will cling to a nearby surface, such as your hand or the sink. This is because the flow of water is more or less following the curvature of your hand, rather than simply continuing in a straight line.

Another example of the Coanda effect can be seen in airplane wings (and starship wings if they’re flying in an atmosphere). The shape of the wing causes air to flow over it in a curved path, which helps to generate lift and keep the plane in the air. The airplane flies because the wings are forced upward. Wings are forced upward because they are tilted and deflect air downward (generating lift). Both the upper and lower surfaces of the wing deflect air. The upper surface of the wing deflects air downward because the airflow ‘sticks’ to the wing surface and follows the tilted wing due to the Coanda Effect.

The Coanda effect has many practical applications in engineering and design. It is used in everything from fluid pumps to airplane design to improve efficiency and performance. Understanding and controlling the Coanda effect is a key area of study in fluid dynamics and aerodynamics.

The Coanda Effect and cars?

The Coanda Effect impacts more than just airplanes and starships. In the case of a moving car, the Coanda effect can have an impact on its performance. By designing the car’s bodywork with curved surfaces, it’s possible to manipulate the airflow around the car to reduce drag and increase downforce. This can result in improved handling, stability, and fuel efficiency.

One example of how the Coanda effect can be utilized in car design is through the use of a rear wing. By shaping the wing to curve downwards, the airflow passing over the wing will tend to follow the curve, creating an area of low pressure underneath the wing. This can increase downforce and improve the car’s grip on the road, especially at high speeds.

Another example is the use of diffusers. A diffuser is a curved surface that channels air from the underside of the car to the rear. This can help to reduce drag by creating a low-pressure area behind the car, which can reduce the turbulence created by the car’s wake.

What about the Coanda Effect and tennis shoes? Can the right shoes let me fly?

While the Coanda Effect can have an impact on the performance of a moving car, it is unlikely to have a significant impact on a person running. This is because the speed of a person running is much slower than the speed of a moving car, and the airflow around a person is relatively simple compared to the complex airflow around a car. Therefore, the Coanda effect is not a major consideration in the design of clothing or equipment for runners. Sorry.