Dispersion in FIA System

As we have seen, on previous slide, a zone of dye (A) injected into a carrier stream initially acquires the shape of a sharp hollow cone (B), since  the center of the stream moves at double the mean flow rate velocity, while friction at the tube walls causes the formation of a trailing edge. As the zone moves downstream, the radial dispersion, if sufficiently fast, will reshape the parabolic  bolus into a “rolling ball” shape.  In this way, the initial square input (A), turns from asymmetric (B)  and ultimately into a Gaussian (C) shape. We will discus this process later, along with RTD response curves and symbols shown here.