controlled by variable valve 404 rollers 401 may be tuned to exhibit a certain frequency which is desirable for obtaining cavitation in the main media stream in concert with the square shape in addition because of the cylindrical shape of the rollers 401 a boundary layer effect enables the gas or media to flow more smoothly through the valve element 403 can function as a gear driver driving the whole assembly and may incorporate a media injection function whereby additional media may be injected into main stream of media being controlled by variable valve assembly 404 in one embodiment variable valve 404 is used to control the flow of air or hydrogen through a hydrogen or hydroxy gas generation system in is known to the inventor that the cavitation of water and other solutions produces the constituents of the h2o molecule as hydrogen and oxygen incorporating valve 404 into the inlet outlet or in the water solution used during electrolysis can enhance the production of hydrogen and oxygen by inducing cavitation in the solution valve 404 can also be utilized to produce cavitation in gas streams associated with electrolysis systems fig4 c is a variable valve 404 in an open position rollers 401 are rotated in opposite directions so that the opening forms a triangle shaped opening 402 this triangle shape may be designed for many purposes one of which may be to purposefully cause cavitation in media or gas streams fig4 d is a variable valve 404 in an open position rollers 401 are rotated in opposite directions so that the opening forms a star shaped opening 402 this star shape may be designed for many purposes one of which may be to purposefully cause cavitation in media or gas streams fig4 e is a variable valve 404 in.