What is " DownForce"??

Downforce is  ...some kind of "Jedi's" force or "Harry potter's " magic ??  

No...we can easily understund on this article.

Let's find out what we and all petroheads are questing for.

First of all, we will start at the most popular and simple way to have downforces, which is the wing.

Wing were started to use for aircrafts and after decades later, some race car designer started to apply for their racing cars to have more grips at the corner.

Before you read this article, please just mind bellow. It's very important.

"The high speed airflow has low pressure and the low speed airflow has high pressure"

Check "Bernoulli's principle" on Wikipedia if you like.

 

Here is tear drop shape obstacle, and shows how the air behaves around it.

The air spread in two directions upper and lowe side of obstacle at the stagnation point.

In this case they have completly the same speed and pressure on both side, which can describe as synmetrical flow.

 

Then if we bend the shape, what will it happen ?

First of all, we can call it airfoil or wing.

 

The above picture shows how it's like the air flow around airfoil.  

In this case we have a different air speed and pressure on each side.

Bending the tear drop, now it obtained a "circulation" 

Therefore, the air speed is reduced on the upper and accelerated on the lower.

*The circulation's story is may bit difficult for the most of people , so please just keep in mind as the reason of the phenomena above.(cf. Kutta–Joukowski theorem)

 

Decelerated flow has high pressure and accelerated flow has low pressure.

We can find pressure difference up to down, in other words the force that pushing the wing down. This is "Downforce"

 

In addition, we can produce downforces in the other way,

which is called "Ground effect"

Above picture shows how the flow field is like around a car on CFD.

*Red : high speed Blue : low speed

Under the floor, we can see some acceralated flow at the beginning of the floor and also end of it.

This means existence of  large low pressure region, so it is pulling the car to the ground and atmospheric pressure pushing it down.

*Red : high pressure  Blue : low pressure 

This is why most of racing cars are running on very low ride high and achieving super fast cornering speeds.