Structure function empirical constant

Short definition of Structure function empirical constant ($C_2$)
The empirical constant relating the longitudinal structure function $D_{LL}$ to the dissipation rate ($\epsilon$)

This is the common definition for Structure function empirical constant, but other definitions maybe discussed within the wiki.

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Dimensional analysis can be used to show that $D_{LL}$ must satisfy the "two-thirds law", i.e., $D_{LL}(r,t)=C_2{\epsilon }^{2/3}{r}^{2/3}$ where $C_2$ is a universal constant.

The value of the constant is generally accepted to be $2.1\pm 0.1$, based on the following studies:

1. Sauvageot (1992): Used Doppler radar measurements of turbulence in the atmosphere to obtain a value of $2.0\pm 0.1$
2. Saddoughi and Veeravalli (1994): Used measurements in a wind tunnel to obtain a value of $2.1\pm 0.1$
3. Sreenivasan (1995): Compiled the results from experimental studies of both grid turbulence and shear flows to conclude that a value of 2.0 agreed best with the spectral inertial subrange equation