Continuity equation

For steady incompressible flow, the same volume flow rate passes through every cross-section of a pipe.

Formula usedA₁v₁ = A₂v₂

Visual cue · fluid

Calculate

What do you want to calculate?

Area 1

Speed 1

Area 2

Speed 2

What do the symbols mean?

A₁area 1

v₁speed 1

A₂area 2

v₂speed 2

Example 1

If the area is divided by four, the flow speed is multiplied by four.

Example 2

With S₁ = 100 cm², v₁ = 1 m/s and S₂ = 25 cm², v₂ = 4 m/s.

Good to knowThe simple relation assumes steady, incompressible flow with no branching between the two sections.