2 mistakes in the postprocessing tools checkCouplingInterval and particleVolume

Hello,

I think I found 2 mistakes in the CFDEM-code. They are only for postprocessing, so nothing major.

The first:
in checkCouplingInterval.C in line 226 is no radius or diameter in the code. Normally there should be a 4*radius^2, but there is only a scaleRad*scaleRad witch is -1*-1

The second:
in particleVolume.C in line 125 is a wrong equation for the volume of a sphere. It should be either pi/6*d^3 or 4pi/3*r^3. Now there is a 4pi/3*d^3

I hope this helps.

Best regards,
Dimitri