Power number

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

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

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

$N_{\mathrm{p}} = {P\over \rho n^{3} d^{5}}$

with

• P: power
• ρ: fluid density
• n: rotational speed
• d: diameter of stirrer

See also

• Reynolds number
• Archimedes number