Dynamic Pressure

Overview

Dynamic pressure is the kinetic energy per unit volume of a fluid flow. It is the pressure increase when a flowing fluid is brought to rest (stagnation).

Formula

$q = \frac{1}{2}\rho v^2$

Calculator

Notes

• Results are approximate and should be verified for critical applications
• Input values should be within reasonable engineering ranges

Common Fluid Densities

Force Due to Dynamic Pressure

The force exerted by dynamic pressure on a surface is calculated as:

$F = p_d A$

where $F$ is the force (N or lbf), $p_d$ is the dynamic pressure (Pa or psf), and $A$ is the area (m² or ft²).

For instance, in a hurricane with air density $\rho = 1.2 \, \text{kg/m}^3$ and wind speed $v = 37 \, \text{m/s}$, the dynamic pressure is:

$p_d = \frac{1}{2} \rho v^2 = \frac{1}{2} \times 1.2 \times 37^2 \approx 821 \, \text{Pa}$

On a wall with area $A = 10 \, \text{m}^2$, the force is:

$F = 821 \, \text{Pa} \times 10 \, \text{m}^2 = 8210 \, \text{N} = 8.2 \, \text{kN}$

Note that this is an idealized calculation; real-world forces may vary due to drag, turbulence, and other aerodynamic effects.

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References

• Original Source