A state‐of‐the‐art review on solid–liquid suspension in stirred reactors throughout the 21st century

Abstract The solid–liquid suspension, which is a complex two‐phase flow, usually conducts in the stirred reactor. It is one of the typical unit operations in chemical engineering, food, biology, pharmaceutical, new energy industries, and so on. The research methods for solid–liquid suspension can be divided into two categories: experimental measurement and numerical simulation. In this paper, the experimental and numerical investigations on this topic since the beginning of the 21st century are comprehensively reviewed. The commonly used experimental measurement methods for the solid phase concentration distribution, flow field, just‐suspension speed, and mixing time are presented in detail, highlighting their advantages and limitations. Numerical simulations, employing various multi‐phase flow models, the Lattice‐Boltzmann method (LBM), the smoothed particle hydrodynamics (SPH) method, as well as the turbulence models and inter‐phase force models, are also reviewed. Their accuracy and applicability in predicting the complex solid–liquid suspension behaviour are discussed. Finally, an outlook for the future study on solid–liquid suspensions in stirred reactors is made. This review paper aims to enhance the understanding of solid–liquid flow dynamics and offers some insights for industrial applications.