A vortex generator is disclosed for flow of a fluid. The vortex generator includes a housing that includes a passage through which the fluid flows. The vortex generator also includes a valve that is movably coupled to the housing between a fully closed position and a fully open position for changing flow of the fluid in the passage. The valve includes an open portion that defines a main aperture for generating a vortex in the flow of the fluid. Also, the valve has an intermediate position between the fully closed position and the fully open position. The housing further includes a recessed portion such that the recessed portion of the housing and the valve cooperate to define a sub-aperture through which the fluid flows when the valve is positioned in the intermediate position. A method of manufacturing the vortex generator is also disclosed.