Historically, the term Tesla principle was used to describe (amongst other things) certain reversible processes invented by Nikola Tesla.[1] However, this phrase is no longer in conventional use. It was developed during Tesla's research in alternating currents where the current's magnitude and direction varied cyclically.
A reversible process in engineering is a process or operation of a system or device such that a net reverse in operation will accomplish the converse of the original function. The principle was that some systems could be reversed and operated in a complementary manner. During a demonstration of the Tesla turbine, the disks revolved and machinery fastened to the shaft was operated by the engine. If the turbine's operation was reversed, the disks acted as a pump.[2]