Hydrodynamic characterization of SPLITT fractionation cells

The efficacy of SPLITT fractionation requires an absence of hydrodynamic mixing between laminae constituting the thin liquid film streaming through a SPLITT cell and it requires structural elements capable of splitting the film evenly along streamplanes. These requirements are examined here by both experimental tests and by a numerical analysis of flow properties near the inlet splitter. The experimental tests, involving dye injection and the injection of pulses of latex particles that may or may not be driven across flow laminae by gravity, show that SPLITT cell performance is close to that of ideal theory at low Reynolds numbers. The computer results verify an absence of mixing under these conditions, but when the Reynolds number and inlet flow asymmetry are both high, vortex motion is found near the inlet splitter edge, suggestive of mixing. The conditions leading to vortex formation are defined. It is shown that tapering the splitter edge suppresses vortex formation.