Flow regime and critical deposition velocity of liquid–solid two-phase flow in pipeline: Progress and perspectives

Pipeline liquid–solid two-phase flow is a significantly important multiphase flow phenomenon widely encountered in both industrial and natural settings. The flow regime of liquid–solid two-phase flow in pipelines plays a crucial role as it represents the macroscopic manifestation of the suspension diffusion mechanism and the slip deposition law of solid particles. This paper provides an overview of research related to flow regimes and critical deposition velocity (CDV) in liquid–solid two-phase flow in pipelines. After briefly reviewing pioneering theoretical research in this field, the paper focuses on recent research in flow regime identification and prediction using state-of-the-art experimental methods and techniques. The review also rigorously assesses the reliability and validity of the methods, results, and conclusions related to the establishment of the CDV, identifying the deficiencies in the current research. Drawing on dimensional analysis and Pearson correlation analysis, the particle Reynolds number is introduced to establish a highly accurate correlation for predicting the CDV under conditions of wide volume concentration. The new correlation yields a mean absolute percentage error of 9.23% and a root mean square error of 10.29% within the volume concentration range of 0.7%–50.8%. This paper aims to provide clear guidance to researchers and professionals in related industries, enabling them to conduct more in-depth investigations according to their research interest and enhance their understanding of liquid–solid two-phase flow systems within pipelines.