Power number

The power number N_p (also known as Newton number) is a commonly used dimensionless number relating the resistance force to the inertia force.

For Newton number, see also Kissing number in the sphere packing problem.

For use in arithmetic and algebra, see Exponentiation.

The power-number has different specifications according to the field of application. E.g., for stirrers the power number is defined as:^[1]

${\displaystyle N_{\mathrm {p} }={\frac {P}{\rho n^{3}D^{5}}}}$

with

• P: power
• ρ: fluid density
• n: rotational speed in revolutions per second
• D: diameter of stirrer