Figure illustrates the theoretically optimal placement of one to four feed points and also presents simulation results in a 22 m 3 bioreactor with four Rushton turbines (A-115 rpm in Table ), which confirm that considerable reductions in the macromixing time-scale are indeed attainable by dividing the feed equally into several points according to the dispersion model. With four symmetrically placed feed points the mixing rate was 29-fold relative to a single feed at the top, which falls short of the ideal 64-fold rate (section 3.3), but is nevertheless quite remarkable: the mixing time-scale (standard deviation 5 % of mean) of a high aspect ratio 22 m 3 reactor was brought from 140 s down to 4.9 s by replacing the single-point top feed by an ideal four-point feed. In comparison, the mixing time-scale in an equal-volume 1:1 aspect ratio vessel stirred with a single impeller and an equal power is expected (eq 5) to be on the order of 17 s. Thus, using an appropriate multi-port feed can result in a mixing rate even greater than what is conventionally obtainable in a corresponding single-impeller configuration with a single feed point.