Body shape

Flow speed Reynolds number (log) Fluid density

Air 1.2

Water 1000

Tracer count

Live stats

ShapeSphere

C_d–

Reynolds Re–

Frontal area A–

Dyn. pressure q–

Drag force F_d–

Drag: F_d = ½·ρ·v²·C_d·A. Bluff bodies (flat plate, cylinder) make the flow separate, leaving a wide low-pressure turbulent wake and high C_d. Streamlining keeps the flow attached, shrinking the wake. Near Re≈3×10⁵ a sphere's boundary layer turns turbulent and reattaches — the famous drag crisis where C_d drops sharply (why golf balls have dimples).