Power number

The power number N_p (also known as Newton number) is a dimensionless number relating the resistance force[?] to the inertia force. In engineering, this number, along with the Reynolds number, is one of the most widely employed dimensionless numbers.

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

N_p=M_t/ρ/n³/d⁵

with

• M_t: torque
• ρ: fluid density
• n: rotational speed[?]
• d: diameter of stirrer