Turbulent Intensity calculation
 

I am facing problem in calculating Turbulent Intensity, with this formula
I = 0.16 (Re_DH) ^ (-1/8)
I observed that high Reynolds number gives lower value of Turbulent Intensity. This is perhaps a ridiculous question. But some think has not yet been clicking. Any help will be highly appreciated.

The turbulence intensity is the fraction/percentage of the velocity fluctuations with respect to the mean flow velocity. The mean velocity scales directly and linearly with Reynolds number. The velocity fluctuations (which is sort of like the turbulent kinetic energy) doesn't scale linearly with Reynolds number. Hence, the turbulence intensity decreases with increasing Reynolds number. However, the turbulence is still increasing. e.g. a smaller percentage of a bigger number can still be a bigger number.

By itself, the turbulence intensity is not a very good description of the physical size/scale of the turbulence, but it is a very convenient normalization scheme for making a non-dimensional parameter out of the turbulent velocity fluctuations.