Investigating coupling and intensification mechanisms in multi‐shaft digesting stirring reactors using <scp>POD</scp>

Abstract The energy crisis and environmental challenges are driving the development of digesting mixers toward larger scales and higher efficiency. This work investigates a multi‐shaft digesting stirring reactor, using large eddy simulations (LES) to obtain flow fields under various operating conditions, validated by simultaneous particle image velocimetry experiments. Subsequently, the LES flow field of stationary and rotating zones was decomposed using proper orthogonal decomposition. By analyzing time coefficients and flow fields for different modes, the characteristics of flow structures and their roles in the mixing process were clarified. Additionally, Lissajous curves and fast Fourier transform analysis were used to analyze wave‐vortex coupling strength at different scales. Two key indicators were examined: minimizing the flow field scale to match the microbial scale and reducing shear forces to protect microorganisms. Based on these, optimal operating conditions were identified. This work provides a theoretical foundation for optimizing digesting reactor operations.