As the number of fluid inlets (N) increases, the solids quantity
in each of N segments of the bed decreases and the observed total
fluid rate is found to be decreasing. A reduction in flow rate leads
to reduction in velocity, which in turn results in higher static pressure
at column bottom. Hence, because of the combined effect of
reduced quantity of solids in each segment and increased static
pressure at column bottom, as N increases, the transition to swirl
bed can occur at lower superficial velocities as shown in Fig. 8.