Stokes number - Citizendia

The Stokes number, named after Irish mathematician George Gabriel Stokes, is a dimensionless number corresponding to the behavior of particles suspended in a fluid flow. The Irish people ( Irish: Muintir na hÉireann, na hÉireannaigh, na Gaeil) are a Western European Ethnic group who originate Sir George Gabriel Stokes 1st Baronet FRS ( 13 August 1819 &ndash 1 February 1903) was a mathematician and physicist In Dimensional analysis, a dimensionless quantity (or more precisely a quantity with the dimensions of 1) is a Quantity without any Physical units Stokes number is defined as the ratio of the stopping distance of a particle to a characteristic dimension of the obstacle, or

$Stk = \frac{\tau\,U_o}{d_c}$

where $τ$ is the relaxation time of the particle, $U o$ is the fluid velocity of the flow well away from the obstacle and $d c$ is the characteristic dimension of the obstacle. For $Stk\gg 1$ , particles will continue in a straight line as the fluid turns around the obstacle therefore impacting on the obstacle. For $Stk\ll1$ , particles will follow the fluid streamlines closely.

References

Fuks, N. A. (1989). The mechanics of aerosols. New York: Dover Publications. ISBN 0-486-66055-9.
Hinds, William C. (1999). Aerosol technology: properties, behavior, and measurement of airborne particles. New York: Wiley. ISBN 0-471-19410-7.

External links

Reynolds number scaling of particle clustering in turbulent aerosols

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