Bernoulli's Principle states that for an incompressible, non-viscous fluid in steady flow, the sum of pressure energy, kinetic energy, and potential energy per unit volume is constant: $P+\frac{1}{2}\rho v^2+\rho gh=\text{constant}$

• $P$: Flow work (pressure energy)
• $\frac{1}{2}\rho v^2$: Kinetic energy per unit volume
• $\rho gh$: Potential energy per unit volume It is essentially an expression of the Conservation of Mechanical Energy for flowing fluids.