# The Bernoulli Equation

The conservation of energy principle in physics applies to many equations. One of these is the Bernoulli equation, which is used for fluids that are flowing. This equation points out that when the flow velocity increases in one region the fluid pressure in another region will decrease. This may seem difficult to understand initially, but when the realization that pressure refers to the density of the energy occurs then this equation makes sense.

The equation used for the Bernoulli equation is P1 + Ω pv 2 over 1 + pgh1= P2 + Ω pv 2 over 2 + pgh2. P refers to the pressure of the fluid, pv refers to the kinetic energy per unit of volume, and pgh refers to the potential energy per unit of volume. This is an advanced physics equation that is not easy to solve for those who have not taken this subject, but anyone familiar with the laws of physics will recognize this equation quickly.

The conservation of energy principle and the Bernoulli equation makes a number of assumptions so that the equation can be solved. The first assumption is that there is no turbulence in the fluid flow, so that it is a laminar flow. This is not always true, and if turbulence is present then this can change the accuracy of the equation and the results. The Bernoulli equation also makes the assumption that the distance between the larger and smaller diameters of the tube is so short that there is no viscous loss involved.

Other assumptions that may be made with the Bernoulli equation include the velocity profile and the average kinetic energy density. With this equation there is always an assumption that the effective flow velocity will always be one half of the velocity maximum possible. The average kinetic energy density is assumed to by one third of the kinetic energy density maximum possible.

All of the assumptions that must be made with the Bernoulli equation may affect the conservation of energy and the final equation results. The inlet tube energy density and the constricted tube energy density are both important factors that are needed to calculate the equation.