Dynamic Pressure

Dynamic pressure is the component of fluid pressure that represents a fluids kinetic energy

The dynamic pressure is a defined property of a moving flow of gas or liquid and can be expressed as

pd = 1/2 ρ v2 (1)

where

pd = dynamic pressure (Pa)

ρ = density of fluid (kg/m3)

v = velocity (m/s)

Some common densities:

• Water at 0oC - 1000 kg/m3 • Water at 32oF - 62.4 lbm/ft3 • Air at 20oC - 1.2 kg/m3 • Air at 59oF - 0.0765 lbm/ft3

Example - Dynamic Viscosity in a Water Flow

The dynamic pressure of water at 20oC, 1000 kg/m3, flowing with velocity 5 m/s, can be calculated using (1) like

pd = 1/2 1000 kg/m3 (5 m/s)2

= 12.5 kPa