Fig. 5.

The effect of geometric variation on pressure requirements. a The relationship between required pressure at inlet, and duct geometry (linear (yellow circles), parabolic (orange diamonds), exponential (dark green triangles), zero taper (pale green square), and literature (blue x) values) at natural spinning speeds (0.02 m s⁻¹). Greater and more severe tapers both increase pressure required to flow representative feedstock. b The effect of geometric variation on required inlet pressure. A limited, representative dataset is shown for clarity (x8 diameter reduction of parabolic (orange dots), exponential (dark green dashes), and linear tapers (yellow dot-dashes)), all curves lie between the limits shown above of Kojic’s model (blue dot-dashes), and the limiting case (zero taper, pale green). See Supplementary Fig. 3 for further details