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Weight Transfer
Splitter Theory
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Splitter Theory
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How does it generate downforce?

E30 M3 EVO III Front Splitter A splitter generates downforce on the front of a car by creating pressure differentials. Actually a splitter produces a "downward force". It is not technically termed "downforce" unless the downward force is large enough to overcome the "upward" force caused by lift. But that is really just semantics.



To understand how a splitter creates downforce you have to know a little bit of fluid mechanics. One should at least be aware of the difference between static pressure and dynamic pressure. It is also instructive to know how dynamic pressure is related to flow velocity. This relationship is given by the well known Bernoulli equation.

How does a splitter generate downforce?
Figure 1

The essential point to be taken from Bernoulli's equation is that the pressure inside an air stream is related to the velocity at which the airstream is moving. As the air stream velocity goes up, the dynamic pressure within the air goes down. In the case of an automobile it is instructive to consider the vehicle as stationary, with the air flow moving towards it, as opposed to the other way around. The oncoming air approaches the vehicle at V1, which is the speed of the vehicle, and a pressure P1 which is related to V1 according to Bernoulli's equation. P1 will be somewhat less then atmospheric.

Figure 1 shows that as the incoming air reaches the front of the vehicle it must come to a stop before it turns to move either up and over, down and under, or around the vehicle. The area where the oncoming air flow comes to a stop is termed the "stagnation point". Since the velocity has gone down, the pressure has gone up (the "stagnation pressure). Thus the front of the moving vehicle is an area of relatively high pressure. Most people are well aware of this already.

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Home
Back to Myths
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More Myths Part 1
Weight Transfer
Splitter Theory
Suspension Travel Theory
Stress Bar Theory
Driving Position