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The titular example of a design decision that violates these principles is the golf ball. You may have heard that golf balls are dimpled to improve their drag performance in the air. For a solar car; surface imperfections are undesirable, so why dimple a golf ball?
It has to do with the body shape. For a bluff body like the golf ball the fluid will tend to seperate from the surface creating a huge pressure drag. We still want to reduce drag, but we can’t streamline a golfball for obvious reasons. The priority for reducing drag is still to eliminate or at least delay flow seperation. How a golf ball does this is with dimples. The dimples create turbulent flow around the golfball, this still increases skin friction, but it delays flow seperation. This flow seperation delay more than makes up for the skin friction losses, and therefore improves the aerodynamics of a golf ball.
We don’t dimple solar cars because if designed correctly there should barely be flow seperation due to the streamlined shape. This means that creating turbulence adds a significant amount of skin drag with no real benefit. |
Car Shape
The following design principles are good to consider when designing solar cars.
A rounded nose that gradually widens will help maintain the laminar boundary layer. The laminar boundary layer will
Reducing the surface area will decrease drag, but may not be feasible due to neading surface area for a solar panel
A smooth surface is the most important factor in keeping a a laminar boundary layer.