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The inferior mechanical performance and freeze–thaw (FT) resistance of recycled concrete are mostly due to the significant water absorption and porosity of recycled coarse particles. In this study, different dosages of zeolite powder were used in recycled concrete. A series of macroscopic tests were used to evaluate the workability and FT durability of zeolite powder-modified recycled concrete (ZPRC). X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to reveal the micro-mechanisms of FT resistance in ZPRC. The results show that the increase in zeolite powder content leads to a decrease in the slump and water absorption of ZPRC. Additionally, ZPRC with 10% zeolite powder has superior mechanical characteristics and tolerance to FT conditions. The higher strength and FT resistance of the ZPRC can be attributed to the particle-filling effect, water storage function, and pozzolanic reaction of zeolite powder, which results in a denser microstructure. The particle-filling effect of zeolite powder promotes the reduction of surface pores in recycled coarse aggregates (RCAs). The water storage function of zeolite powder can provide water for the secondary hydration of cement particles while reducing the free water content in ZPRC. The pozzolanic reaction of zeolite powder can also promote the generation of hydrated calcium silicate and anorthite, thereby making the microstructure of ZPRC more compact. These results provide theoretical guidance for the engineering application of recycled concrete in cold regions.

In this paper, the coupled weakly compressible (WC) and total Lagrangian (TL) smoothed particle hydrodynamics (SPH) model based on the open-source multi-physics and multi-resolution SPHinXsys library is used to simulate the structural deformation and failure problem in fluid-structure interaction (FSI). Aiming at the problem that the original TLSPH method could not simulate the cracks and their propagation, the fracture model based on TLSPH is established, and then verified by fast-loading and slow-loading cases respectively. With the fracture model in hand, the TLSPH method is coupled with the WCSPH method to simulate the breaking dam flow impacting on an elastic/elastoplastic baffle. The comparison with the literature data shows that the present coupled WC-TLSPH model can accurately simulate the FSI problem where figurative fracture process is involved, indicating the compromising potential of the established model to simulate the elastoplastic structural failure in scientific and industrial applications.

A large amount of wastewater from industrial and urban residents enters rivers and lakes through the sewage outlet, causing a deterioration of water quality near the sewage outlet. The smoothed particle hydrodynamics (SPH) formulation based on the open-source Fortran code SPHysics is extended to solve the advective diffusion for the evolution of the pollution distribution with the shallow water equation (SWE). Several numerical cases, such as the uniform flow and dam-break flows in one and two dimensions, are studied to verify the accuracy of the present SPH-SWE diffusion model. The results are in good agreement with the analytical solutions. The concentration of the negative value and oscillation could be avoided. It demonstrates that the current SPH-SWE diffusion model has good stability and reliability for solving the pollutant transport equation. The actual terrain case is also simulated to predict the concentration distribution of the river. The concentration is distributed in the center of the Nanmenxia River, where the flow velocity is relatively high. The simulation results are reasonable, implying that it has a high potential in predicting the diffusion process of pollutants in the actual terrain.

Due to its Lagrangian nature, Smoothed Particle Hydrodynamics (SPH) has been used to solve a variety of fluid-dynamic processes with highly nonlinear deformation such as debris flows, wave breaking and impact, multi-phase mixing processes, jet impact, flooding and tsunami inundation, and fluid–structure interactions. In this study, the SPH method is applied to solve the two-dimensional Shallow Water Equations (SWEs), and the solution proposed was validated against two open-source case studies of a 2-D dry-bed dam break with particle splitting and a 2-D dam break with a rectangular obstacle downstream. In addition to the improvement and optimization of the existing algorithm, the CPU-OpenMP parallel computing was also implemented, and it was proven that the CPU-OpenMP parallel computing enhanced the performance for solving the SPH-SWE model, after testing it against three large sets of particles involved in the computational process. The free surface and velocities of the experimental flows were simulated accurately by the numerical model proposed, showing the ability of the SPH model to predict the behavior of debris flows induced by dam-breaks. This validation of the model is crucial to confirm its use in predicting landslides’ behavior in field case studies so that it will be possible to reduce the damage that they cause. All the changes made in the SPH-SWEs method are made open-source in this paper so that more researchers can benefit from the results of this research and understand the characteristics and advantages of the solution proposed.

The hydropower system in the Upper Yellow River (UYR), one of the largest hydropower bases in China, plays a vital role in the energy structure of the Qinghai Power Grid. Due to management difficulties, there is still considerable room for improvement in the joint operation of this system. This paper presents a general LINGO-based integrated framework to study the operation of the UYR hydropower system. The framework is easy to use for operators with little experience in mathematical modeling, takes full advantage of LINGO's capabilities (such as its solving capacity and multi-threading ability), and packs its three layers (the user layer, the coordination layer, and the base layer) together into an integrated solution that is robust and efficient and represents an effective tool for data/scenario management and analysis. The framework is general and can be easily transferred to other hydropower systems with minimal effort, and it can be extended as the base layer is enriched. The multi-objective model that represents the trade-off between power quantity (i.e., maximum energy production) and power reliability (i.e., firm output) of hydropower operation has been formulated. With equivalent transformations, the optimization problem can be solved by the nonlinear programming (NLP) solvers embedded in the LINGO software, such as the General Solver, the Multi-start Solver, and the Global Solver. Both simulation and optimization are performed to verify the model's accuracy and to evaluate the operation of the UYR hydropower system. A total of 13 hydropower plants currently in operation are involved, including two pivotal storage reservoirs on the Yellow River, which are the Longyangxia Reservoir and the Liujiaxia Reservoir. Historical hydrological data from multiple years (2000-2010) are provided as input to the model for analysis. The results are as follows. 1) Assuming that the reservoirs are all in operation (in fact, some reservoirs were not operational or did not collect all of the relevant data during the study period), the energy production is estimated as 267.7, 357.5, and 358.3×108 KWh for the Qinghai Power Grid during dry, normal, and wet years, respectively. 2) Assuming that the hydropower system is operated jointly, the firm output can reach 3110 MW (reliability of 100%) and 3510 MW (reliability of 90%). Moreover, a decrease in energy production from the Longyangxia Reservoir can bring about a very large increase in firm output from the hydropower system. 3) The maximum energy production can reach 297.7, 363.9, and 411.4×108 KWh during dry, normal, and wet years, respectively. The trade-off curve between maximum energy production and firm output is also provided for reference.

This paper presents a numerical study of the hydraulic jump on corrugated riverbed using the Smoothed Particle Hydrodynamics (SPH) method. By simulating an experimental benchmark example, the SPH model is demonstrated to predict the wave profile, velocity field, and energy dissipation rate of hydraulic jump with good accuracy. Using the validated SPH model, the dynamic evolvement of the hydraulic jump on corrugated riverbed is studied focusing on the vortex pattern, jump length, water depth after hydraulic jump, and energy dissipation rate. In addition, the influences of corrugation height and length on the characteristics of hydraulic jump are parametrically investigated.

In this paper, we use the parallel open source code parallelSPHysics based on the weakly compressible Smoothed Particle Hydrodynamics (WCSPH) approach to study a spillway flow over stepped stairs. SPH is a robust mesh-free particle modelling technique and has great potential in treating the free surfaces in spillway hydraulics. A laboratory experiment is carried out for the different flow discharges and spillway step geometries. The physical model is constructed from a prototype reservoir dam in the practical field. During the experiment, flow discharge over the weir crest, free surface, velocity and pressure profiles along the spillway are measured. In the present SPH study, a straightforward push-paddle model is used to generate the steady inflow discharge in front of the weir. The parallelSPHysics model is first validated by a documented benchmark case of skimming flow over a stepped spillway. Subsequently, it is used to reproduce a laboratory experiment based on a prototype hydraulic dam project located in Qinghai Province, China. The detailed comparisons are made on the pressure profiles on the steps between the SPH results and experimental data. The energy dissipation features of the flows under different flow conditions are also discussed. It is shown that the pressure on the horizontal face of the steps demonstrates an S-shape, while on the vertical face it is negative on the upper part and positive on the lower part. The energy dissipation efficiency of the spillway could reach nearly 80%.

This paper applied a Smoothed Particle Hydrodynamics (SPH) approach to solve Shallow Water Equations (SWEs) to study practical dam-break flows. The computational program is based on the open source code SWE-SPHysics, where a Monotone Upstream-centered Scheme for Conservation Laws (MUSCL) reconstruction method is used to improve the Riemann solution with Lax-Friedrichs flux. A virtual boundary particle method is applied to treat the solid boundary. The model is first tested on two benchmark collapses of water columns with the existence of downstream obstacle. Subsequently the model is applied to forecast a prototype dam-break flood, which might occur in South-Gate Gorges Reservoir area of Qinghai Province, China. It shows that the SWE-SPH modeling approach could provide a promising simulation tool for practical dam-break flows in engineering scale.

Draft tube vortex rope is considered a special cavitation flow phenomenon in tubular turbine units. Cavitation vortex rope is one of the most detrimental factors affecting the safety of hydraulic turbines. In this study, ANSYS CFX software was utilized to numerically simulate the internal cavitation flow of a hydraulic turbine draft tube. The evolution of the cavitation vortex core was characterized by vortex line distribution and vorticity transport equation. The shape and number of blades influenced the revolving direction and distribution characteristics of the vortex close to the runner cone, which formed a counterclockwise-clockwise-counterclockwise distribution pattern. Simultaneously, there were many secondary flows in the draft tube. Mutual cancellation and dissipation between the flows was one of the reasons for reduction in vorticity. When the cross-sectional shape of the draft tube was changed, the vorticity was distributed from the center of the vortex rope to all parts of the cross-sectional draft tube, with extreme values at the center and at the walls. The vortex stretching and dilatation terms played a major role in the change in vorticity, with the baroclinic torque having an effect at the center of the vortex rope, this study is helpful to understand the flow of water in the draft tube and guide the design and optimization of the draft tube in engineering application [ABSTRACT FROM AUTHOR]