Undular hydraulic jumps are characterized by a smooth rise of the free surface, followed by a train of stationary waves. These jumps sometimes occur in natural waterways and rivers. Numerical difficulties are especially distinct when the flow condition is close to the critical value because of the high sensitivity of the near-critical flow field to flow and channel conditions. Furthermore, the free surface has a wavy shape, which may indicate the occurrence of several transitions from supercritical to subcritical states and vice versa (i.e., undular hydraulic jumps). In this study, a flow model is used to predict an undular hydraulic jump in a rectangular open channel. The model is based on the general two-dimensional, Reynolds-averaged, Navier-Stokes flow equations. The resulting set of partial differential equations is solved using the FLOW-3D solver. The results are compared with the experimental data to validate the model. The comparative analysis shows that the proposed model yields good results. Several types of undular hydraulic jumps occurring in different situations are then simulated to prove the potential application of the model.
Type 2 diabetes mellitus (T2DM) is a metabolic disease that can be a significant cause of cardiovascular disease (CVD), leading to macrovascular and microvascular diseases. Many researchers around the world have investigated the effects of weight change on micro and macro CVD in patients with T2DM. This study aimed to investigate the effect of weight change (weight gain and loss) on microvascular and macrovascular complications in patients with T2DM. We searched PubMed, Scopus and Google Scholar from the database until January 2023. We screened the title, abstract, and full text of articles, and after quality assessment, we extracted data from interrelated ones into this systematic review. Reviewing the results of 11 cohort studies with 219,839 individuals (T2DM patients) showed that weight loss caused an increase in the mortality rate in diabetic patients, while weight gain after diabetes diagnosis increased the risk of CVD, chronic kidney disease (CKD), microvascular disease, stroke and mortality. It should be noted that severe body weight variability increases the mortality rate and the risk of microvascular disease. Unlike other studies, one study showed that more than 5% weight gain positively affected CVD and coronary heart disease in T2DM patients. Generally, weight change in patients with T2DM is an essential sign of cardiovascular complications. According to our findings, the risk of cardiovascular complications in patients with weight loss is seen to be higher than in patients with weight gain. In regular patients with body mass index (BMI), stable weight in a healthy range is reported to decrease the risk of CVD.