Introduction. In gas industry, predicting sand erosion damage of pipelines by sand particles is a difficult task because this process is strongly influenced by many factors. Particulate matter carried away by the multiphase product during production can seriously compromise the integrity of fluid handling structures such as pipelines and elbows. Materials and methods. A three-dimensional numerical modelling approach in three-phase gas – liquid – solid flows was used to analyze erosion processes in pipe elbows. A key advantage of using CFD is that it can provide a wealth of information such as the effect of various parameters on erosion, maximum erosion rate, and erosion-prone areas. A variation of the Euler method for multiphase fluids was used to simulate three-dimensional unsteady gas-water annular flows with the presence of sand particles. Results. The results showed that a vertical pipe with two elbows is more prone to erosion at the second elbow than atthe first elbow. However, in a horizontal pipe with two elbows, it can be concluded that the first elbow is more proneto erosion. On the other hand, erosion at L/D = 0 showed the maximum erosion rate among all the geometries studied. Conclusions. In a vertical pipe, the second elbow of the pipeline is more susceptible to erosion. In addition, the erosion rate at the second elbow of vertical and horizontal pipes is the same for all studied geometries. The pipeline with L/D = 10 showed the optimal layout choice for vertical and horizontal pipe with an average erosion rate of 57.9 mm/year, which representsthe lowest erosion rate among the options studied.

Introduction: The quality of sleep and physical activity is specially important in the quality of life of the elderly. The aim of this study was to determine the relationship between sleep quality and quality of life of the elderly with cardiovascular disease referred to Ali Ebn Abi Taleb Hospital in Rafsanjan City in 2021. Methods: In this descriptive study, the participants of the study included all the cardiovascular elderly patients referred to Ali Ebn Abi Taleb Hospital in Rafsanjan City in the first 6 months of 2021. A total of 292 people were selected as the sample using purposive sampling method. Data collection tools included three standard questionnaires, including Baecke physical activity, Petersburg sleep quality and Ware and Sherbourne quality of life (SF-36). Independent t-test, one-way analysis of variance and chi-square test were used to analyze the data. The SPSS software version 16 used was for analyzing the data. Results: The results showed that with increasing physical activity, the quality of life also increases and with increasing the quality of sleep, the quality of life increased. There was also a significant correlation between psychological quality of life with physical activity (P<0.001 and r = 0.777) and sleep quality (P<0.001 and r = -0.804). Conclusion: According to the research findings, it is recommended to create a wide and healthy physical activity and healthy leisure time for the elderly and to develop counseling programs for the elderly. Therefore, the quality of life and sleep quality skills training should be provided.

Introduction. Prediction of multiphase flow patterns in pipelines of gas and oil industry is a complicated hydrodynamic process. Hydraulics of gas-liquid flows and erosion processes in pipelines with many bends in which gas, water, oil and air move are insufficiently studied. There are known studies of movement in single-phase flow conditions with one elbow, which is insufficient for design of modern pipeline systems. Therefore, there is a need for in-depth analysis of interaction of media in multiphase flow and transported sand particles. In this paper the effects of elbows on multiphase flow hydraulics and erosion of pipe sections are investigated using computational fluid dynamics (CFD) modelling tools for 100 seconds’ of process. Materials and methods. A liquid volume model (VOF) was used to simulate three-phase flow: air-water with solids in a pipe with two elbows. Turbulence effects have been accounted for with the RNG k–ε model. The model verification methods from previous studies have been used. For the numerical solution, the Ansys Fluent version 20.1 software package has been used. The results of CFD modelling of the volumetric gas content have shown a good agreement with the available experimental data. Results. The results showed that the change in the flow regime remains unchanged before the first elbow and after the se-cond elbow in the cork flow. However, for the initial churn flow regime, the flow regime varies at different segments of the flow area before and after each elbow. Conclusions. The preliminary churn flow in the upper vertical section was transformed to wavy stratified flow in the horizontal section between the two elbows and wavy annular flow in the vertical pipe after the second elbow. The flow pattern in slug flow maintained same after the first elbow, but the Taylor bubbles are lengthier in the horizontal section between the first and second elbows.