A fluidic variable swirl port for an internal combustion engine includes a curved entry chamber centered on the valve axis with an inlet duct extending from one side. A small control port opens laterally into one or both sides of the inlet duct through which air or exhaust gas may be admitted to offset the path of the main inlet flow stream and generate swirl in the connecting engine cylinder when the control port is open while allowing free flow at higher flow rates when the control port is closed. Alternate embodiments and an engine operating system are also disclosed.

Methods and apparatus for controlling fluid flow through microchannels by use of passive valves or stopping means comprised of abrupt microchannel widenings in the microchannels are presented. Such passive fluid flow barriers create pressure barriers impeding flow of solution past the passive fluid flow barriers until enough force is built up to overcome the force of the pressure barrier. Use of such stopping means acting as passive barriers or valves allows the flow of fluids through microchannels to be regulated so as to allow fluids to be mixed or diluted after being introduced via a single channel, or to be split into multiple channels without the need for individual pipetting. Flow through the multiple channels can be regulated to allow a series of sister wells or chambers to all fill prior to the fluid flowing beyond any one of the sister wells or chambers. The filling of sister wells or chambers in this manner allows all wells or chambers to undergo reactions in unison. The use of air ducts in microchannels to prevent trapping of air in the microchannels is also presented.