switches in turbulenceProperties should be optional

Functionality to add/problem to solve

In turbulenceProperties file, two switches are mandatory:

turbulence on;
printCoefficients on;

Both of them are so rarely used they could be switched to optional with the default value set to "on". Turning them optional and getting rid of them, or at least the first one from the setup would still keep the backward compatibility easily and people will not be puzzled.

Target audience

Especially new users are puzzled by "turbulence on" switch as I can see on the courses.

Proposal

Turning those switches optional or alternatively renaming the "turbulence on" to something less misleading.

solveTurbulence yes/no;

or similar.