TRAJECTORY LENGTH DISTRIBUTION (TLD), A NOVEL CONCEPT TO CHARACTERIZEMIXING IN FLOW SYSTEMS

A novel function is introduced to characterize mixing in flow systems, the Trajectory Length Distribution (TLD) representing the distributio n of distances covered by fluid elements (or particles) in the system. ?his allows to define a macromixing index comparing the mean trajecto ry length to a characteristic dimension of the vessel. As an illustrat ion. preliminary results are presented, showing Return Length Distribu tions to given surfacer in a stirred vessel, obtained by particle trac king using video cameras. Theoretical expressions of TLDs in various i deal reactors - recycle loop, axially dispersed plug flow, Zwietering' s reactor, cascade of reactors in series - are derived, showing the po tential interest of the TLD concept.