Aerodynamics of concave surfaces (JR IS guest blog by Collin Hendershot)

My name is Collin Hendershot. For my Junior Independent Study project I observed the effect of concavity on the aerodynamics of high speed automobiles. The two important aerodynamic characteristics of automobiles are downforce and drag. Downforce is the force of air pushing a car toward the road and drag is the force on the car from air opposing the forward motion of the car. Downforce increases a car’s stability and turning speed, and drag decreases a car’s top speed and fuel economy. An aerodynamically efficient car will have a high downforce to drag ratio. To increase a vehicles downforce designers often include a rear wing on the car. I designed 5 different rear wings with a leading edge defined by the function

which creates wings with increasing concavity as the value for a increases (Figure 1). The downforce and drag for each wing was recorded and then the downforce to drag ratio of each wing was calculated. The results are pictured in Figure 2 and the a = 2 wing design has the largest downforce to drag ratio, 3.8, therefore it is the most efficient wing design.