For sharp-cornered bluff bodies, like square cylinders and plates held transverse to the flow direction, this equation is applicable with the drag coefficient as a constant value when the Reynolds number is greater than 1000.
12.
This is because bluff bodies ( non-streamlined bodies ), like bridge decks, in a fluid stream shed wakes, whose characteristics depend on the size and shape of the body and the properties of the fluid.
13.
A large amount of studies and researches has been conducted concerning these interactions and their dependencies, aiming the understanding of the aerodynamic phenomena that arise due to them, such as the K�rm�n vortex street, galloping, buffeting and flutter, mainly regarding bluff bodies.
14.
The reference length can vary depending on the analysis to be performed : for body with circle sections such as circular cyliners or spheres, one usually chooses the diameter; for an airfoil, a generic noncircular cylinder or a bluff body or a revolution body like a fuselage or a submarine, it is usually the profile chord or the profile thickness, or some other given widths that are in fact stable design inputs; for flow channels usually the hydraulic diameter ) about which the fluid is flowing.
