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The mobile flume has the advantages of not easy to be silted up and can be moved and reused in many places, etc. Compared with the fixed type, the streamlined shape of the measuring flume has good hydraulic performance, and the diffusion section of the flume has a great influence on the hydraulic performance, however, there is a lack of research on the design principle and method of the diffusion section at present. In order to study the influence of flume structure on hydraulic properties, and to provide theoretical guidance for the design of streamlined flume structure, This paper establishes a D40Ushaped channel simulation model, and then uses FLOW-3D to simulate the semi-elliptical with semi-elliptical, semi-elliptical with parabolic, semi-elliptical with arc, semi-elliptical with Myring curve, and fish-shaped flume under flow rates of 35, 45, and 55 L/s. Furthermore, the accuracy effect of numerical simulation is verified by prototype test, and then the design principle and method of diffusion section are discussed. Finally, based on the isight platform, the semi-elliptical with Myring curve and fish-shaped flume with better hydraulic performance are optimized. The results show that the relative error between the numerical simulation and the experimental water depth is 0.1%-1.3% and the relative errors of velocity in upstream, throat and downstream sections are 0.19%-6.63%, 0.06%-6.15% and 0.02%-6.22% at 45 L/s flow rate, respectively. The numerical simulation results have high accuracy. The Froude number in the upstream of the five flumes is less than 0.5, and the maximum backwater height is 5.71 cm, which meets the requirements of flow measurement accuracy and channel safety. Among them, the head loss and backwater height of the semi-elliptical with Myring curve flume are the lowest, the critical submergence degree of the semi-elliptical with semi-elliptical flume is the highest, and the Froude number is the smallest. The design principle of the diffusion section of the flume is: under the condition of slightly reducing the critical submergence degree, the first half of the diffusion section is designed as a curve with larger curvature to reduce the upstream backwater; the second half is designed as a curve with opposite curvature and smaller curvature to improve the flow state, smooth the water flow and reduce the head loss. After optimization, the curvature of the first half of the semi-ellipse with Myring curve and the fish-shape flume increases, and the curvature of the second half decreases, the backwater and Froude number are reduced, and the head loss is reduced by 5.5% and 6.3%, respectively. The study can provide theoretical guidance for the design and optimization of streamlined measuring tank structures. [ABSTRACT FROM AUTHOR]

Electro-induced deformation of water droplets is a complex physical phenomenon that involves coupling electric and fluid fields. It is commonly found on the surface of insulator fittings and equipment high-voltage equalizing rings after rain. Efficient and fast numerical simulation methods are the foundation for revealing the physical mechanisms of raindrop deformation and corona excitation. This article addresses the common problems of long calculation time and complex convergence in the numerical calculation of three-dimensional electric fluid models. A numerical simulation method based on field equivalence was proposed. Starting from the principle of light deflection, a water droplet deformation observation platform based on the shadow method is constructed. The effectiveness of this method was verified by comparing numerical simulation and experimental shooting results. The research results indicate that the relative error between the electric field constructed by this method and the original electric field is within 0. 01%. The spray morphology of water droplets obtained from numerical simulation under positive polarity DC voltage agrees with the experiment. By comparing the width and length of the water droplet root, middle, and head, it is shown that the relative error between numerical simulation and experiment is within 10%, verifying the effectiveness of the simulation method in this paper. At the same time, while ensuring convergence, the calculation time is reduced from 8 hours to 1 hour. [ABSTRACT FROM AUTHOR]

Reasonable support form and support parameters are the key to ensuring the stability of the roadway surrounding rock. The joint support effect of bolt + metal mesh + shot grouting in the Grade IV surrounding rock area of the drainage roadway of Julong Copper Mine in Xizang is poor. In this paper, for the problems of support in the Grade IV surrounding rock area of the drainage roadway of Julong Copper Mine, bolt and steel arch support, as well as the thickness of shot grouting, is introduced on the basis of the existing support. Different bolt support parameters are designed and optimized using finite element numerical simulation software. The results show that there is an obvious stress addition phenomenon at the roadway surrounding rock roof. With the increase of bolt support parameters, the maximum stress value at the roadway roof increases. With the increase of row spacing between bolts, the maximum displacement of the roadway roof increases, the bolt spacing increases from 1.2 m to 2.0 m, and the displacement of the roadway roof is 4 mm, 4.38 mm, and 4.82 mm, respectively. The optimal support parameter of the bolts is 1.6 m x 2.4 m. The results of the study provide theoretical references for the selection of the support parameters of the bolts of similar roadways. [ABSTRACT FROM AUTHOR]

Realizing quantitative evaluation of disaster reduction benefits of debris flow retaining dams has important theoretical and practical significance for optimizing engineering design and protecting the safety of people's lives. and property. The paper uses numerical simulation methods to obtain the mud depth, flow velocity, and range of debris flow under different operating conditions, establishes two risk evaluation index systems based on the area of high risk level and the total risk degree, proposes a quantitative evaluation method for the disaster reduction benefits of retaining dams, and conducts an empirical study using the Chutougou debris flow as an example. According to the evaluation method for disaster reduction benefits of retaining dams, it is possible to analyze the disaster reduction benefits of the proposed and existing projects and their combinations, determine whether they have achieved the disaster reduction goals, and compare and quantify the importance of different projects in disaster reduction, which can provide a basis and reference for the construction and improvement of debris flow retaining dams. The disaster reduction benefits per unit height can reflect the value of risk reduction per meter of retaining dam heightening, and can be applied to the determination of optimal engineering combination scheme of debris flow retaining dams. The change rule of the total risk degree and the disaster reduction benefits of the area with high risk level is consistent, indicating that both risk assessment methods can reflect the disaster reduction benefits of the combination of retaining dams and their changes. [ABSTRACT FROM AUTHOR]

The development of hydrogen energy industry is an important measure for China to achieve the goal of "carbon peak and carbon neutrality", accelerate green and low-carbon development, and comprehensively improve resource utilization efficiency. Compared with high-pressure gaseous hydrogen storage, solid hydrogen storage and other hydrogen storage methods, low temperature liquid hydrogen storage has the advantages of high effective hydrogen storage density, low transportation cost, high vaporization purity and low storage and transportation pressure, so it is the most potential hydrogen storage method for high-power fuel cells. In this paper, Fluent is used to perform unsteady calculations on the liquid hydrogen supply system of a high-power marine fuel cell, and study the minimum gas hydrogen charging speed required to completely discharge the liquid hydrogen in the tank within a given time. The numerical simulation results show that during the process of high-temperature gas hydrogen filling into the liquid hydrogen tank, there is a local high temperature at the entrance due to heat accumulation. The hydrogen enters the liquid hydrogen tank and flows in the horizontal direction, flowing downward under the action of gravity and the wall, and through the convection heat transfer with the low-temperature fluid in the tank, it will change the fluid density in different areas, so that the gas hydrogen and liquid hydrogen produce vortices respectively. [ABSTRACT FROM AUTHOR]

Based on the theory of Darcy, s law and solute transport, this paper took a ground water-sealed oil depot project on a certain island as the engineering support and conducted numerical simulation research using COMSOL finite element software to analyze the variations in seepage field in caverns under different design schemes. The water-sealed safety of the cavern was evaluated. The development degree of seawater intrusion in the reservoir area was explored. The research indicated that the project required the installation of a horizontal water curtain, and the design pressure value of the horizontal water curtain should not be less than 0.2 MPa. The variation in the depth of the main cavern had a small impact on the water seal, and the recommended buried depth was -45 m. When the main carvern was fully excavated without oil storage, seawater would intrude into the caverns, with seawater intrusion showing a pattern of rapid intrusion followed by gradual intrusion, entering from the bottom of the main cavern. [ABSTRACT FROM AUTHOR]

The inhomogeneity of the lake and land underlying surfaces has large influences on the development and evolution of severe convective weather. Poyang Lake is the largest freshwater lake in China, and its area exhibits distinct monthly and seasonal variations. However, the underlying surface of the lake in the Weather Research and Forecast (WRF) model is usually assumed to be constant, which is different from the real situation and leads to model forecast errors. In this paper, the WRFV3.9 model was used to simulate a severe convective weather event that occurred over the Poyang Lake region during a summer night. Lake area sensitivity experiments were conducted to analyze the influence of Poyang Lake on the development and evolution of severe convective weather and its mechanism. The results showed that the 2 m temperature over the lake surface was significantly higher than that over the land surface during summer night. The land breeze converged and rose over the lake region, while there was a sinking and divergent airflow over the shore, which caused precipitation to decrease over the west bank of the lake but increased over the lake. The subsequent lake-removing sensitivity experiment further confirmed the warming effect of Poyang Lake. Poyang Lake could inhibit precipitation occurred over the west bank of the lake and intensify precipitation over the lake by stimulating the secondary circulation of land-breeze. The precipitation of the lake-removing experiment increased by 20% over the west side of the lake, and decreased by 16% over the lake, suggesting the impact of the lake on precipitation intensity. In addition, it was found that the precipitation over the lake increased by 7%, 16%, 30% and 43% in the lake-expanding sensitivity experiments, where the lake area was expanded by 1.5, 2.5, 3.5 and 4 times, respectively, further confirming the sensitivity of severe convection intensity to the area of Poyang Lake. These results indicated that attention should be paid to the possible trend of convections weakening (enhancing) before (after) entering the Poyang Lake region during summer nights. Meanwhile, when a numerical model was used to simulate the severe convection weather, the real lake area could be introduced into the underlying surface of the model when the real lake area differed greatly from the default climatic value used in the numerical model, to improve the forecasting capability for severe convective weather occurring over lake regions. [ABSTRACT FROM AUTHOR]

Crack propagation velocity is a crucial discussion for understanding dynamic fracture. Classical dynamic fracture theory predicts a “forbidden velocity zone” for mode Ⅱ cracks, i.e., the velocity between the Rayleigh and shear wave speeds. However， supershear transition has been demonstrated theoretically and experimentally for mode-Ⅱ crack constrained to weak interfaces. Such transition is commonly accepted to be governed by the Burridge-Andrews mechanism (also known as “mother-daughter” crack), which predicts direct nucleation of a secondary intersonic daughter crack induced at the Rayleigh wave speed. Nevertheless, to our knowledge, “mother-daughter” crack pairs are rarely reported with visual observations, and the supershear rupture without the daughter crack forming has also been found in some previous reports. Recently, Prof. Liangbin Li ’s group at University of Science and Technology of China and the coworkers reported the Sub-Rayleigh to supershear transition of dynamic mode-Ⅱ cracks based on numerical simulations. Their numerical experiments successfully reproduced the “mother-daughter ” cracks for the first time in phase-field fracture modeling, as well as the supershear transition without the daughter crack. Given that, a crack tip blunting-tearing hypothesis was presented to explain that cracks comply with different mechanisms from Sub-Rayleigh to supershear regimes, and a critical prestress level was revealed below which no supershear transition can be accomplished from the Sub-Rayleigh propagation. Furthermore, the criteria were also proposed for predicting the occurrence of the daughter crack through systematic simulations. This paper briefly presents their progress in the studying of the Sub-Rayleigh to supershear transition for dynamic mode-Ⅱ interfacial fracture. [ABSTRACT FROM AUTHOR]

Sewage treatment is one of the main contents of environmental protection, so it is very important to provide a theoretical basis for sewage treatment through the analysis of the mechanism. Based on the classical material conservation mathematical model of microorganism and substrate, this paper analyzed the existence and stability of each equilibrium point of the model by calculating the Jacobian matrix of the model, and gave the sufficient conditions to make the stability of the equilibrium point of the model. The numerical simulation method is used to effectively verify the analysis results. In order to improve the effect of sewage treatment, we put forward some suggestions on the setting of relevant parameters in the sewage treatment process from the perspective of mathematical analysis, and verified the correctness of the suggestions by numerical simulation method. [ABSTRACT FROM AUTHOR]

Aiming at the problems ol slow filling elliciency and low and unstable sand discharge concentration in the traditional vertical sand silo working mode, a continuous high-concentration and stable sand discharge working mode is proposed, and the maintenance ol sand storage height is the key to this working mode. In this paper, the centrilugal test is used to investigate the lunctional relationship between the underllow concentration and the sand storage height, and then the static settlement test is used to obtain the feeding parameters, and the hydro dynamic software is used to simulate and analyze the sand storage process ol the vertical sand storage,to verily the feasibility ol the functional relationship, and the dynamic mesh technology is used to simulate and monitor the sand discharge concentration, overllow concentration and sand surlace height change ol sand discharge process with dilierent storage heights, and to investigate the optimal sand storage height, and to provide a comprehensive solution to the problem. The simulated monitoring ol sand discharge concentration and sand surlace height changes during sand discharge at dillerent storage heights using dynamic grid technology is used to comprehensively investigate the optimal sand storage height, which provides an important reference lor the study ol continuous sand discharge Irom vertical sand silo. The results show that:there is no significant dillerence between the numerical simulation and the lunctional relationship, and the lunctional relationship between the underllow concentration and the sand storage height is feasible； 11. 8m is the optimal sand storage height lor the vertical sand silo to continuously discharge sand with high concentration and stability. [ABSTRACT FROM AUTHOR]

Rainfall infiltration can cause a decrease in the strength of the rock and soil mass on the dump slope, increase the bulk density of the upper rock and soil mass, and reduce the stability of the slope. This paper takes a mine dump slope as the background, and uses GeoStudio software to simulate and analyze the pore water pressure characteristics and safety factors under different rainfall durations. The simulation results indicate that as the duration of rainfall increases, the limit value of pore water pressure continuously increases, and the pore water pressure increases towards the top of the slope, while the corresponding safety factor decreases. The study provides references for the stability of the dump slope in the mine. [ABSTRACT FROM AUTHOR]