(70e) The Simplest Stirred Tank for Laminar Mixing: Mixing in a Vessel Agitated By An Off-Centered and Angled Disc

We study the mixing structure, performance, and short term dynamics in round bottomed laminar tanks agitated by an eccentrically located angled disc. We define eccentricity (E=e/R) as the ratio of the distance of the axis of rotation from the center line of the tank (e) and the tank radius (R). The structural and dynamic features observed at different eccentricity values were compared using planar laser induced fluorescence (p-LIF) techniques and computational fluid dynamics (CFD) calculations. A Poincaré analysis demonstrates the chaotic nature of the flow induced by eccentricity. Practically globally chaotic conditions are observed for E=0.42 and E=0.50, with mixing times of 5-8 minutes at Re=416. We study the effect of different injection points on the short term mixing dynamics and we calculate axial flow rates and Power numbers. Stirred tanks agitated by an eccentrically located angled disc are a simple and cost effective system for laminar mixing applications.