cuttingPlane requires huge amount of RAM in single precision

Dear All,

my transient simulation crashes when it tries to export cuttingPlanes VTK on the fly for lack of RAM memory, when running the solver (pisoFoam) in single precision. Everything runs fine if i run the double precision version. I couldn't explain this behaviour.

Thanks for your help

Marco

## Reattaching the author to the issue ticket: @okocha ##