Anyone know what the purpose of this tube from drivers side head to intake is ?

recirculation of oil vapours into the intake stream for combustion.

It's just the breather/suction end of the PCV loop.

The purpose is what mollusc said, AND to make your Throttle Body FUNKY!

Thanks There is no valve or anything just a open tube

Yep, no valve.
The passenger side has the oil separator/spiral in it.

Thanks landy fellows