Stokesian

Stokesian is an adjective associated with the work of Sir George Gabriel Stokes and, more broadly, with the theories and equations named after him in fluid dynamics and related fields. The term is commonly used to describe phenomena that involve viscous, low Reynolds number flow, where inertial effects are negligible and the governing motions are described by the Stokes equations. In this context, Stokesian flow or Creeping flow refers to situations such as the slow movement of particles through a viscous fluid.

A prominent use of the term appears in Stokesian dynamics, a computational framework developed to model the motion of many interacting particles suspended in a viscous fluid. In Stokesian dynamics, the fluid is assumed to obey the Stokes equations, and the hydrodynamic interactions among particles are represented through mobility or resistance matrices. The method typically separates far-field hydrodynamic interactions, often treated with multipole expansions, from near-field lubrication forces that become significant when particles approach each other. It can be extended to include Brownian motion, enabling simulations of colloidal suspensions and their rheological behavior.

Stokesian concepts and methods are applied to problems in colloid science, rheology, and microfluidics, where low Reynolds number conditions prevail. They help quantify collective particle motions, effective viscosity, normal stresses, and sedimentation rates in suspensions. The term remains a standard descriptor in scientific literature for theories and calculations grounded in Stokesian hydrodynamics.