---
tag: 13CB7V2YM4
kind: concept
name: Stokes flow
msc: [76D07, 35Q35]
sources:
  - url: https://en.wikipedia.org/wiki/Stokes_flow
same_as:
  wikidata: Q674202
  wikipedia: Stokes flow
---

## Summary

Stokes flow is the flow of a viscous fluid in which viscous forces are much larger than inertial forces.
It is governed by the Stokes equations, the linear system obtained from the [[Navier–Stokes equations|18KXZHVF4M]] by dropping the nonlinear term and the time derivative.
Because the equations are linear, solutions can be added and many problems can be solved exactly.
Stokes flow models very small organisms, slow flows of very viscous fluids and flows in thin films.

## Explanations

### L1 human

When honey creeps down a spoon, or a bacterium swims in water, inertia hardly matters.
If the pushing stops, the fluid stops almost at once.
In this regime the pressure and the friction inside the fluid balance each other exactly.
A standard example is flow in a channel between two plates, where the speed profile is a parabola, fastest in the middle and zero at the walls.