Calculadora de Coeficiente de Arrasto
Calcule o coeficiente de arrasto aerodinâmico a partir da força de arrasto, velocidade, densidade do fluido e área de referência.
Drag Force
1.1515 N
Drag Force vs Drag Coefficient (Cd)
Formula
Aerodynamic Drag Force
Drag opposes the motion of an object through a fluid.
Formula
F_d = 0.5 Cd rho A v^2
Common Cd values: sphere 0.47, streamlined body 0.04, flat plate 1.28, car 0.25-0.45.
Exemplo Resolvido
Sphere (Cd = 0.47) of cross-section 0.01 m2 in air at 20 m/s.
- 01F_d = 0.5 * 0.47 * 1.225 * 0.01 * 400
- 02F_d = 0.235 * 1.225 * 4
- 03F_d = 1.152 N
Perguntas Frequentes
Why does drag scale with velocity squared?
At moderate to high speeds, drag is dominated by inertial effects (pressure drag). The kinetic energy of deflected air grows as v^2, so the force does too.
What determines the drag coefficient?
Primarily the shape and surface roughness. Streamlined shapes direct flow smoothly with less separation, giving lower Cd.
Does Cd depend on Reynolds number?
Yes, especially for smooth objects. The drag crisis for a sphere occurs around Re = 500 000, where Cd drops sharply.
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