In the S.N. Goenka vipassana tradition the meditator tries to reach a 'freeflow' of sensations on and in the body. Is this 'freeflow' comparable with Pīti?
Free flow is loosely used for Piti. Initially it is subtle vibrations which you feel. As you practice this spreads to your body. These vibrations are pleasant.
The free flow is when the whole body dissolves into subtle vibrations, and you reach the stage of bhanga, total dissolution. It causes pīti (pleasant sensation, rapture, bliss) and if not careful you can develop attachment to it.