According to Mech Eng 1.01, fluid flows more easily in this duct from right to left than from left to right. Careful choice of the geometrical details enables that difference to be maximised, for a given fluid and speed.
Today’s invention makes use of this basic asymmetry by forming a marine drive unit from a matrix of these ‘leaky valves.’ The valves would be wafted fore and aft within a submerged duct, preferentially propelling fluid more to the left than to the right (and thus driving the vehicle slowly rightwards).
Each valve would be driven axially by an independent magnetic field, fluctuating in both frequency and amplitude so that:
a) the vessel’s acoustic signature would be more like white noise and thus harder to identify than the less variable frequency of a rotary drive
b) electrically-driven valve matrices could be located in pods anywhere on the hull of a vessel
c) each matrix could sustain some significant damage without stopping
d) marine creatures, such as whales, would be less disturbed by the resulting clamour.
It just occurred to me that fitting these to the surfaces of a future generation of submarines that swim like fish would add to the ‘grip’ they exert on the surrounding fluid and allow speedier movement (think of each cylindrical section of an eel’s body, twisting to the left and right about a vertical axis).