BUG: Inconsistent energy spectrum with boxTurb
Summary
The utility boxTurb is supposed to generate a divergencefree velocity field with the following energy spectrum
E(\kappa) = A_0 (\frac{\kappa}{\kappa_0})^4 e^{2 (\frac{\kappa}{\kappa_0})^2}

However, when analyzing the energy spectrum from the file
graphs/0/Ek.xy
which appears appear running the applicationboxTurb
, I don't see at the expected spectrum from the previous equation. I attach a picture comparing the obtained spectrum vs the theoretical spectrum. 
The computation of the ensemble kinetic energy presents a multiplication by a factor for 3 which seems wrong for me as
k = \int_0^{\infty} E(\kappa) d\kappa = average(\sum \frac{1}{2} mag(U)^2) = \frac{3}{2} u_{RMS}^2
Info<< "k("
<< runTime.timeName()
<< ") = "
<< 3.0/2.0*average(magSqr(U)).value() << endl;
 At last the values of the wavenumber output in
graphs/0/Ek.xy
seems to not be in accordance with the mesh. One expects the maximum wavenumber to be\kappa_{max}= \frac{\pi}{h}
whereh
is the cell size but I in my tests the maximum value of the wavenumber is not consistent with the theoretical formula
Steps to reproduce
 Run
boxTurb
in theboxTurb16
tutorial increasing the number of cells in each direction to64
and changing the scale parameter toscale 6.28318530718;
This value corresponds to 2pi. Decaying isotropic turbulence are commonly simulated using a box with 2pi edge length  Compare the data from the file
graphs/0/Ek.xy
with the theoretical spectrum from the previous equation
Example case
What is the current bug behaviour?
What is the expected correct behavior?
Relevant logs and/or images
Environment information
 OpenFOAM version : v2006
 Operating system : ubuntu
 Hardware info : 
 Compiler : 