Bernoulli's Equation

Written by Jerry Ratzlaff. Posted in Fluid Mechanics

The following assumptions must be met for the Bernoulli's equation to apply:

  • The fluid must be incompressible, even though pressure varies, the density must remain constant.
  • The streamline must not enter the boundary layer.  (Bernoulli's equation is not applicable where there are viscous forces, such as in the boundary layer.)

Abbreviated as \(Be\)


\(p \;+\; \rho gh \;+\; \frac {1}{2} \rho v^2   = constant\)


\(p\) = pressure at the point

\(\rho\) = density of the fluid at all points in the fluid

\(g\) = gravitational acceleration

\(h\) = height, the point above a reference plane

\(v\) = fluid velocity