The mean residence time 𝑡̅ resembles the time after which 50% of a tracer substance has left the reactor. The Bodenstein number is part of equation 2 and can be calculated by dividing the product of flow velocity u and channel length L by the axial dispersion coefficient Dax. Bo reflects the ratio of convective to dispersive flow in axial direction. Small Bo represent more pronounced backmixing and therefore a broad residence time distribution. For an ideal continuously stirred tank system, Bo approaches 0, whereas for an ideal tubular reactor with ideal plug flow behaviour, Bo approaches infinity. In the rarest cases, however, reactor systems exist which exhibit ideal behaviour.