Bernoulli's Principle Simulator (2D)

Flow

Inlet speed 8.0 m/s

Throat narrowing 62%

Fluid

Venturi Tube

Wide — speed

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Wide — pressure

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Throat — speed

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Throat — pressure

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Ball Levitation

Ball height

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Offset from center

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P + ½ρv² = const — where the tube narrows, air speeds up and its pressure drops. The rising jet uses the same drop to hold the ball up and pull it back to center.

How it works

Bernoulli's equation, P + ½ρv² + ρgh ≈ const along a streamline, says that where a fluid speeds up, its pressure must fall (ignoring the small height term in a horizontal tube). Continuity forces the speed-up: with constant volume flow, A₁v₁ = A₂v₂, so a narrower cross-section area A means a higher velocity v.

In the left tube, air enters wide and slow, accelerates through the narrow throat, then slows back down as the tube widens again. The pressure readouts are computed directly from the two equations — reduce the throat width and watch the speed climb and the pressure fall further below atmospheric.

On the right, a nozzle blows a jet straight up. Its core is fastest and lowest-pressure; drifting sideways moves the ball into slower, higher-pressure air outside the jet, which pushes it back toward the center — the same pressure difference that lets an airfoil generate lift or a perfume atomizer draw liquid up a tube.

Real examples: aircraft wings, carburetors, spray bottles, chimney draft.
Drag the ball with your mouse or finger to displace it and watch it re-center.

Drag the ball to nudge it — release to see it self-center