Terminal Velocity (Small Sphere, Stokes)

v_t = 2·(ρ_p - ρ_f)·g·r^2 / (9·μ)

What it says

The terminal settling speed of a small sphere in Stokes flow, where gravity, buoyancy, and viscous drag balance.

Symbol	Quantity	Dimension
`v_t`	Terminal speed (m/s)	`L T^-1`
`ρ_p`	Particle density (kg/m^3)	`M L^-3`
`ρ_f`	Fluid density (kg/m^3)	`M L^-3`
`g`	Gravitational acceleration (9.80665 m/s^2)	`L T^-2`
`r`	Sphere radius (m)	`L`
`μ`	Dynamic viscosity (Pa·s)	`M L^-1 T^-1`

Enter what you know. No account needed.

ρ_p — Particle density (kg/m^3)ρ_f — Fluid density (kg/m^3)r — Sphere radius (m)μ — Dynamic viscosity (Pa·s)