From Patterns to\nCocktails: A Novel Visualization\nMethod for Turbulent Flow Fields in Stirred Reactors

Visualizing flow fields in stirred reactors under turbulent\nconditions\nremains a long-standing challenge. Inspired by bartenders creating\npatterns while mixing cocktails, we introduced pearlescent powder\nto achieve flow field visualization. We captured images of wall flow\nstructures in various reactors and extracted their fractal dimensions.\nIn comparison to the mixing time, this method effectively reflects\nthe degree of chaos and the variability of mixing performance. Additionally,\nthe fractal dimension shows sensitivity greater than that of traditional\nchaos metrics. By integrating proper orthogonal decomposition (POD)\nand dynamic mode decomposition (DMD) techniques, we clarified the\ninteractions between vortices of different scales within the reactors,\nconfirmed by Hilbert–Huang spectrum analysis. These analyses\nrevealed the underlying mechanisms for reduced mixing performance\nin triple-shaft stirred reactors, validated through large-eddy simulation\n(LES) results. Furthermore, this work provides a novel method for\nrapidly validating computational fluid dynamics (CFD) models through\ndirect observation of wall flow structures.