With the development of coal mining, the use of elbows has diversified the forms of underground backfill pipelines, which has inevitably complicated the transportation characteristics of filling slurry in the pipeline, thus affecting the entire backfilling system. The objective of this study is to numerically investigate the running state of cemented paste backfilling (CPB) slurry and coarse particles at different velocities by transporting in bend pipes. To better understand the transportation state of CPB slurry in pipeline, a computational fluid dynamics (CFD) model—mixture model was developed to study the transportation of CPB slurry. The volume distribution of coarse particles in slurry under different pipe types and different flow rates, as well as the velocity profiles of slurry at different positions, were simulated and analyzed, and the pressure losses under different pipe types were compared. The results show that the distribution of coarse particles varies with the tube type, and the effect of coarse particles on the position of tube wall changes with the increase in velocity. The high-speed zone of CPB slurry will move toward the outer wall of the elbow with the increase in velocity. The pressure loss of CPB slurry in the vertical–horizontal pipeline is larger than that in the horizontal–vertical pipeline, and the difference is larger in the bend section. This study provides a theoretical and meaningful reference for CPB slurry backfilling operations in different bends.

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Respirable particulate matter (RSP) is currently very harmful to the human body, potentially causing pulmonary silicosis, allergic rhinitis, acute bronchitis, and pulmonary heart disease. Therefore, the study of the deposition pattern of RSP in the human respiratory system is key in the prevention, treatment, and research of related diseases, whereby the main methods are computer simulation, in vitro solid models, and theoretical analysis. This paper summarizes and analyzes past deposition of RSP in the respiratory tract and also describes them in specific case studies such as COPD and COVID-19 patients, based on the review of the evidence, direction, and focus of future research focusing on simulation, experimentation, and related applications of RSP deposition in the respiratory tract.

Research on the underground filling mining of Cemented Paste Backfilling (CPB) slurry shows that it alleviates the underground subsidence and environmental problems caused by mining, making a strong contribution to the realization of green mining. To optimize performance, cost reductions, and the recycling of agricultural solid waste, some researchers have studied using volcanic fly ash (FA) to replace part of cement. Corn straw fly ash (CSFA) may be used to replace the same amount of part of cement or FA, as corn straw can improve the mechanical properties of FA to make the CPB slurry for filling goaf. On this basis, in order to ensure a good flow of the CPB slurry in the pipeline, we need to conduct pipeline tests on the slurry of these different cement materials to verify their feasibility. In this article, Fluent has been used to study the CPB slurry transport properties in the two cases mentioned above through numerical simulation. Comparing the velocity distribution and pressure loss changes of the CPB slurry with different proportions in the horizontal pipeline provides a reference for future CPB slurry research. The results show that: (1) FA forms a lubricating layer in the pipe wall due to its "ball effect", which effectively reduces the yield stress and pressure loss of the CPB slurry in the pipe, and plays a positive role in the transportation of CPB in the pipe; and (2) CSFA increases the CPB slurry transport pressure loss due to its irregular particle size, increasing the risk of pipe wear. The results are helpful for better understanding and designing paste filling material for mine.

The leakages in water pipeline networks sometimes negatively affect the environment, health, and economy. Therefore, leak detection methods play a crucial role in detecting and localizing leaks. These methods are categorized into internal and external detection methods, each having its advantages and certain limitations. The internal system has its detection based on the field sensors to monitor internal pipeline parameters such as temperature and pressure, thereby inferring a leak. However, the mobility of the sensing module in the pipeline is affected by the model drag coefficient. The low drag coefficient causes the module to quickly lost control in the pipeline leading to false detection. Therefore, this study is about designing and numerically analysing a new model to achieve a higher drag value of the sensing system. The drag value of various models is determined with the help of CFD simulations in ANSYS. The outcome of this study is a new model with a drag value of 0.6915. It was achieved by implementing an aerodynamic shape, a more significant surface contact area in the middle, and canted fins at the front of the . Both pressure, drag, and skin friction were increased, so a higher drag value of the sensing module can be achieved. Through this, the mobility and control of modules in the pipeline can be improved, improving leak detection accuracy.