# Talk:Strouhal number

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Is the frequency term in the Strouhal Number in "radians/second", or "cycles/second" (assuming V = m/sec and D = m)?

Radians are a non-dimensional unit, such that cycles per second is the same thing as radians per second except that there are 2*pi (a dimensionless number) radians in each cycle. So, the frequency is in fact in cycles per second, or if multiplied by 2*pi, radians per second. --ABQCat 01:32, 4 Nov 2004 (UTC)

Frequency is actually blade frequency, so the cycles/second of the rotor is blade frequency/ # of blades.

## Symbols

I note that $v$ is used to denote velocity; I propose that V be used instead. This will maintain consistency with other articles, in which V denotes velocity, and $v$ denotes viscosity. Any objections? Logicman1966 (talk) 12:21, 10 March 2009 (UTC)

## Dimensions and Units

I came to this page specifically to determine whether the Strouhal number is defined in terms of 'rad/sec' or 'cycles/sec', and how it relates to 'reduced frequency', in particular for an aeroelastic application. I found clarification for neither. It may be that the definition is discipline/application specific, as in I had never considered counting number of blades, but it makes sense for turbines and propellers. This article needs either a single universal definition for the terms used, or needs to be expanded to acknowledge the different ways that the number is defined in practice. As always, anyone who uses the symbol 'St' should define what they mean by it, including in this article.
PoqVaUSA (talk) 18:00, 10 October 2012 (UTC)