## [Stokes' Law](/index.php/stokes-law) ## [Stokes' Law](https://engineering.quantumdictionary.io/stokes-law-0) [![Engineering & Applied Technologies Dictionary](/sites/default/files/styles/large/public/2026-01/Engineering%20%26%20Applied%20Technologies.png.webp?itok=_IKO7_-n)](/index.php/topic-specific-dictionaries/engineering-applied-technologies) **Engineering & Applied Technologies Dictionary** Definition An analytical expression for the viscous drag force F on a small rigid sphere of radius a moving at steady, low-Reynolds-number relative velocity v through an incompressible Newtonian fluid: F = 6π μ a v directed opposite to v, valid under creeping-flow conditions where inertial effects are negligible and the no-slip boundary condition holds on the sphere surface. ## [Stokes' Law](https://health.quantumdictionary.io/stokes-law-1) [![Health & Life Sciences Dictionary](/sites/default/files/styles/large/public/2026-01/Health%20%26%20Life%20Sciences.png.webp?itok=yyyaiQOY)](/index.php/topic-specific-dictionaries/health-life-sciences) **Health & Life Sciences Dictionary** Definition An analytic expression for the terminal settling velocity of a small rigid spherical particle in a quiescent Newtonian fluid at low Reynolds number (Re << 1): v = (2/9)(r^2(ρ_p − ρ_f)g)/μ, where r is particle radius, ρ_p and ρ_f are particle and fluid densities, g is gravity and μ is fluid viscosity; valid for isolated spheres, negligible wall effects, and laminar Stokes flow. ## [Stokes' Law](https://commerce.quantumdictionary.io/stokes-law-2) [![Commerce, Trade & Industry Dictionary](/sites/default/files/styles/large/public/2026-01/Commerce%2C%20Trade%20%26%20Industry.png.webp?itok=nh8jKPLm)](/index.php/topic-specific-dictionaries/commerce-trade-industry) **Commerce, Trade & Industry Dictionary** Definition An analytical expression for the terminal settling (steady) velocity of a single small rigid spherical particle moving under gravity through a viscous, Newtonian fluid in the creeping‑flow regime.