Astrophysics (Index)About

Stokes number

(Stk, St)
(measure of a particle's tendency to flow 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 due to inertia, i.e., a more massive particle.

(measure,fluid dynamics,ratio)
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