Evaluation of Laminar Mixing Performance in an Oscillatory Baffled Reactor: Experimental and Numerical Approaches

In regions with a low oscillatory Reynolds number, an oscillatory baffled reactor (OBR) exhibits the folding and stretching of fluid, resulting in the mixing observed within the baffle sections. In this study, an analysis of the mixing mechanism and an evaluation of mixing performance were conducted using experimental methods and numerical simulations to visualize the boundary between the liquid phases and track its shape changes. The ratio of oscillation stroke to baffle interval length, the open ratio of the baffle's cross-sectional area, and the length of the baffle intervals were varied. A glycerin-water solution was used, and the boundary line was colored with rhodamine, forming a film-like layer at the orifice, which was then visualized using sheet laser fluorescence. Oscillatory flow was applied, and changes in the length of the boundary line and the boundary area were measured for one oscillation cycle. For the numerical calculations, the velocity field was first computed, followed by the arrangement of virtual particles to represent the boundary line. The shape of the boundary line obtained from the experiments was consistent with the simulation results, and the trends in the length of the boundary lines for the first cycle were generally consistent as well. Therefore, the experimental results confirmed that the boundary area increases exponentially, consistent with the simulation results.