Incompressible flow primitive
Flow continuity
Inputs
Area normal to the mean flow direction at section 1.
User-entered mean velocity at section 1.
Area normal to the mean flow direction at section 2.
Results
Volumetric flow rateQ
2
Second mean velocityv₂
5
Area ratio A₁/A₂A₁/A₂
2.5
1Q = A₁v₁ = A₂v₂
A first-pass number, not a code check, certification, or approval. Read the method and its limits below. What this is and is not.
Nearby: Hydrostatic pressure · Pipe mean velocity · Bernoulli equation · Dynamic pressure
Method
Formula, when it applies, and when it does not
Relate area, velocity, and volumetric flow for a steady incompressible flow through two displayed cross-sections.
Q = A₁v₁ = A₂v₂
When
- Steady flow
- Incompressible fluid
- Mean cross-section velocity
Don’t
- This is continuity for steady incompressible flow using mean section velocities. It does not calculate pressure change, loss, turbulence, cavitation, pipe sizing, or pump performance.
White, Fluid Mechanics