Astrophysics (Index)About

Stokes number

(Stk, St)
(measure of a particle's tendency to follow the flow of a fluid)

A Stokes number (Stk or St) of a particle sitting in a fluid is a characterization of its tendency to flow with the fluid. It is the ratio of two characteristic times:

Stk = t0 u0 / l0

(The latter two divide out to be the reciprocal of a time.) Particles with a low Stokes number tend to "stay with" the fluid flow, whereas with a higher stokes number take time to respond to the fluid motion, presumably more massive particles with more inertia.


(measure,fluid dynamics,ratio)
Further reading:
https://en.wikipedia.org/wiki/Stokes_number
https://www.chemeurope.com/en/encyclopedia/Stokes_number.html

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