A fluidic apparatus for generating a variable flow of pressurized fluid comprising: (a) a nozzle assembly defining a three-segment fluidic structure having an inlet segment, a power nozzle segment and an outlet segment (14, 134) all having lumens which are in fluid communication with one another and aligned on a central axis; (b) a source of pressurized fluid in fluid communication with said inlet segment; (c) said power nozzle assembly inlet segment having a large proximal inlet aperture and terminating distally in a smaller power nozzle aperture defined within said power nozzle segment, where the power nozzle aperture has a selected power nozzle width (W P) and depth (D P); (d) said power nozzle segment having a selected first lumen area defined by the width (W P) of the power nozzle aperture and terminating distally in a selected second larger lumen area defined by a setback region (48, 140) having a setback depth (D S) and a setback width (W s) which is selected to control exhaust flow characteristics and which defines the beginning of said outlet segment; (e) said power nozzle segment further including first and second control ports (CP1, CP2) spaced apart from one another; wherein the first and second control ports (CP1, CP2) are each in fluid communication with the power nozzle lumen and are on opposite sides of the central axis within the power nozzle segment; the first and second control ports are below the setback region; (f) said outlet segment (14, 134) having walls (60, 62, 64, 66, 142, 144, 146, 148) terminating at an exhaust aperture, the walls (60, 62, 64, 66, 142, 144, 146, 148) of the outlet segment being angled with respect to said central axis at a selected angle (92, 150); characterised in that the fluidic apparatus is configured to attach to a leaf blower device, (g) wherein said control ports (CP1, CP2) include laterally projecting control boxes (78, 80) that are linked through an inertance loop, the inertance loop is an external hose connected by opposing ends (82, 84) to tubular stubs (86, 88) on the control boxes; and; (h) wherein the setback width (Ws) is 1.1 to 1.5 times the power nozzle aperture width (Wp), the power nozzle depth (D P) and the setback depth (D S) are equal to each other and the outlet walls (60, 62, 64, 66, 142, 144, 146, 148) diverge at a wall angle (92, 150) of 20 to 60 degrees to provide an oscillating mode. (a) a nozzle assembly defining a three-segment fluidic structure having an inlet segment, a power nozzle segment and an outlet segment (14, 134) all having lumens which are in fluid communication with one another and aligned on a central axis; (b) a source of pressurized fluid in fluid communication with said inlet segment; (c) said power nozzle assembly inlet segment having a large proximal inlet aperture and terminating distally in a smaller power nozzle aperture defined within said power nozzle segment, where the power nozzle aperture has a selected power nozzle width (W P) and depth (D P); (d) said power nozzle segment having a selected first lumen area defined by the width (W P) of the power nozzle aperture and terminating distally in a selected second larger lumen area defined by a setback region (48, 140) having a setback depth (D S) and a setback width (W s) which is selected to control exhaust flow characteristics and which defines the beginning of said outlet segment; (e) said power nozzle segment further including first and second control ports (CP1, CP2) spaced apart from one another; wherein the first and second control ports (CP1, CP2) are each in fluid communication with the power nozzle lumen and are on opposite sides of the central axis within the power nozzle segment; the first and second control ports are below the setback region; (f) said outlet segment (14, 134) having walls (60, 62, 64, 66, 142, 144, 146, 148) terminating at an exhaust aperture, the walls (60, 62, 64, 66, 142, 144, 146, 148) of the outlet segment being angled with respect to said central axis at a selected angle (92, 150); characterised in that the fluidic apparatus is configured to attach to a leaf blower device, (g) wherein said control ports (CP1, CP2) include laterally projecting control boxes (78, 80) that are linked through an inertance loop, the inertance loop is an external hose connected by opposing ends (82, 84) to tubular stubs (86, 88) on the control boxes; and; (h) wherein the setback width (Ws) is 1.1 to 1.5 times the power nozzle aperture width (Wp), the power nozzle depth (D P) and the setback depth (D S) are equal to each other and the outlet walls (60, 62, 64, 66, 142, 144, 146, 148) diverge at a wall angle (92, 150) of 20 to 60 degrees to provide an oscillating mode.