In this work, a thorough model for the now in annular cell provided with various feed systems, based on an experimental determination of the residence time distribution, was presented for values of the Reynolds number in the range 100 to 5000. Using the plug flow model with axial dispersion, followed by a series of perfectly stirred plug-reactors, it was shown that the non-maintained swirling flow induced by a tangential inlet exhibits a very pronounced piston behavior in conjunction with a stirred zone due to the flow inlet/outlet system in the cell. When an axial inlet or an inlet perpendicular to the cell was used, the percentage of the overall reactor volume having a plug flow with respect to the one with a tangential inlet was decreased.