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Deep-sea slurry pump is a crucial component for achieving vertical transportation of ore particles in pump-pipe lifting deep-sea mining systems. However, traditional mining pump structures face challenges, such as insufficient particle flow capacity and blockage susceptibility, which affect the slurry pump's operational stability. This study introduces a novel deep-sea slurry pump design that incorporates the non-clogging structural characteristics of a screw mixed flow impeller combined with a diffuser. The pump flow capacity was evaluated using the CFD-DEM (Computational Fluid Dynamics - Discrete Element Method) coupling method for transporting 10 mm spherical particles at various flow rates. The motion patterns and non-uniform distribution characteristics of particles were analyzed qualitatively and quantitatively within the pump under different inflow conditions. The proposed pump demonstrated a robust coarse particle overflow capacity for varying particle transport states and unequal particle distribution among flow components. The particle quantity changed consistently throughout the transportation process and was divided into a growth phase and a stable phase. The main flow components exhibited a dynamic non-uniform particle flow with a more pronounced periodic nature in the impeller channel. The degree of non-uniform particle flow in the diffuser channel was inversely related to the flow rate， and was higher compared to the impeller channel.

The results are presented from an experimental study to investigate three-dimensional turbulence structure profiles, including turbulence intensity and Reynolds stress, of different non-uniform open channel flows over smooth bed in subcritical flow regime. In the analysis, the uniform flow profiles have been used to compare with those of the non-uniform flows to investigate their time-averaged spatial flow turbulence structure characteristics. The measured non-uniform velocity profiles are used to verify the von Karman constant κ and to estimate sets of log-law integration constant Br and wake parameter П, where their findings are also compared with values from previous studies. From κ, Br and П findings, it has been found that the log-wake law can sufficiently represent the non-uniform flow in its non-modified form, and all κ, Br and П follow universal rules for different bed roughness conditions. The non-uniform flow experiments also show that both the turbulence intensity and Reynolds stress are governed well by exponential pressure gradient parameter β equations. Their exponential constants are described by quadratic functions in the investigated β range. Through this experimental study, it has been observed that the decelerating flow shows higher empirical constants, in both the turbulence intensity and Reynolds stress compared to the accelerating flow. The decelerating flow also has stronger dominance to determine the flow non-uniformity, because it presents higher Reynolds stress profile than uniform flow, whereas the accelerating flow does not.

In this paper, the flow characteristics of a continuous-type liquid–liquid pintle injector are described, focusing on the differential impact of a non-uniform center-flow distribution on single- and bi-injection methodologies as well as the cavitation effect on the spray angle. Using cold-flow experiments, jet-type flows of the center propellant caused by a non-uniform flow distribution were observed during a single injection. This resulted in an augmented pressure drop, as opposed to the flow characteristics of uniform single-film injection. By contrast, bi-injection modalities exhibited a substantial reduction in the pressure drop of the center propellant, underscoring a more equitable flow distribution. Moreover, the occurrence of cavitation in the center propellant was found to markedly affect the spray angle. By considering the injection exit area reduction caused by cavitation, the spray-angle prediction accuracy increased. The findings of this study are expected to reveal the interplay between flow distribution and pressure drop as well as that between cavitation and the spray angle in pintle injectors. Through this understanding, this study provides crucial considerations for the development of more efficient propulsion systems.

Floods can cause widespread devastation, resulting in loss of life and damages to personal property and critical public health infrastructure. River flooding is the most common type of flooding in many parts of the world. It occurs when a water body exceeds its capacity to hold water and usually happens due to prolonged heavy rainfall. The one-dimensional (1-D) hydrodynamic model is used to evaluate the geomorphic effectiveness of floods on the Ambica river basin, South Gujarat region. The study region was subjected to frequent flooding. Major flood event occurred in the year 1981, 1984, 1994, 1997, 2001, 2003, 2004, 2006, 2013 and 2014. In the present study, the geometry of the Ambica river, floodplain of Unai, and past flood data have been used to develop a 1-D hydrodynamic model using HEC-RAS (6.0.0)software. After collecting the required data, the 1-D hydrodynamic model has been developed to simulate the floods of the years 1984 and 1994. The segment of the Ambica river reach with approximately 9 km length between Padam Dungari to Sidhai village is selected for analysis. The study area consists of 23 cross-sections. The model is used to evaluate steady flow analysis, flood conveyance performance, and uniform flow analysis. The outcome obtained from the model is in the form of water depth and water surface elevation. Based on the above results, it shows that the low-lying areas of Navsari city are susceptible to flooding when the discharge in the river exceeds 6500 m 3 /s. This study can be utilised for disaster management, flood management, early warning system by authorities in addition to infrastructure growth decisions.

In recent decades, the environment has been seriously polluted by the hazardous exhaust components of diesel engines. The international community, which is dedicated to preserving the harmony between nature and humanity, has taken this seriously and imposed strict regulations on Diesel engine manufacturers regarding the quantity of exhaust components from Diesel engines that may apply to the standards of EURO-VI. The SCR technology attempted to reduce the problem somewhat, but the associated problems of solid particle formation on the pipe walls, ammonia slip, and incomplete NOx reduction led to the development of new technology - solid selective catalytic reduction. The use of solid ammonium salt for ammonia generation has shown better results in NOx reduction and reduction of solid particle formation compared to SCR. However, it was not possible to fully resolve the ammonia slip issue. A uniform flow rate of ammonia through the SCR catalyst can reduce NOx efficiently. In this paper, the role of mixer design in achieving a uniform flow rate of ammonia is investigated in detail. The results show that an optimized mixer design leads to efficient reduction of NOx and thus reduces ammonia slip to a great extent. When the mixer is placed near the ammonia injection point, the most homogeneous ammonia distribution is achieved for flow through the SCR catalyst.

Li, Q. and Hong, B.G., 2020. Numerical calculation of non-uniform flow field in water area at the end of a breakwater. In: Bai, X. and Zhou, H. (eds.), Advances in Water Resources, Environmental Protection, and Sustainable Development. Journal of Coastal Research, Special Issue No. 115, pp. 494-497. Coconut Creek (Florida), ISSN 0749-0208. The control of ship motion in harbor water is a frontier problem in unmanned ship research. In harbor waters, affected by the shore type, the varied flow pattern has a great influence on ship motion. In this paper, numerical calculation method was used to study the influence of non-uniform flow on ship motion. a control-volume-based finite-difference scheme of the three-dimensional rectangular coordinate system was used for solving the two-phase transient Navier-Stokes equations. The dynamic process of water interaction with the ship and its (ship) free surface was investigated with the help of volume of fluid (VOF) technique. Moreover, the flow field and mechanical characteristics of the ship in the breakwater were analyzed under the action of cross flow. The force analysis of ship with respect to time and space such as the ship sailing out of breakwater with certain sail-angle and speed characteristics are also investigated. Finally, these numerical results were compared with that of experimental data which has a nice correlation with each other.

The aim of the study was to assess the possibility of using the empirical formulas to determine the roughness coefficient in gravel-bed streams, the bed slopes of which range from 0.006 to 0.047. Another aim was to determine the impact of taking into account the conditions of non-uniform flow on the application of these formulas and to develop the correlation relationships between the roughness coefficient and water surface slope and also between the roughness coefficient and friction slope in order to estimate the roughness coefficient in gravel-bed streams. The studies were conducted in eight measuring sections of streams located in the Kraków-Częstochowa Upland, southern Poland. The roughness coefficient for these sections was calculated from the transformed Bernoulli equation based on the results of surveys and hydrometric measurements. The values of were compared with the calculation results obtained from fourteen empirical formulas presenting the roughness coefficient as a function of slope. The Lacey, Riggs, Bray and Sauer formulas were found to provide an approximate estimate of the value, while the best roughness coefficient estimation results were obtained using the Riggs formula. It was also found that taking into account the non-uniform flow and using the friction slope in the formulas instead of the bed slope or water surface slope did not improve the estimated values of the roughness coefficient using the tested formulas. It was shown that the lack of differences in the RMSE and MAE error values calculated for the developed correlation equations between the roughness coefficient and the friction slope or with the water surface slope also indicate no influence of the assumed friction slope or water surface slope on the value of the estimated roughness coefficient.

Multiple hypotheses have been advanced to explain the occurrence of pools in gravel bed rivers. These hypotheses were developed without a hydrodynamic model of how open channel flow is affected by pools, and it is not clear why and when the flow phenomena they describe might occur. Laboratory experiments are warranted to improve our understanding of how a gradual convective deceleration and acceleration of the flow, without flow separation, redistributes flow and turbulence in an open channel. Experiments are conducted in a 1.5 m wide flume with a 0.25 m deep, 7.29 m long straight pool, entry and exit slopes of 5°, vertical side walls, and gravel sediment (D50 = 9.9 mm). Three‐dimensional velocity components are recorded at 50 Hz using Nortek Vectrinos. Velocity and Reynolds stress profiles in the channel centerline agree with previous results in nonuniform flow and include increased Reynolds stress during deceleration and high velocity near the bed during acceleration. Lateral flow convergence occurs where depth is increasing, which demonstrates that convergence is induced during flow deceleration and does not require a lateral flow constriction. Turbulence during deceleration is characterized by sweeps angled toward the sidewall of the channel, an effect that could lead to the formation of a nonuniform pool depth through lateral gradients in the deposition of mobile sediment. A conceptual model of pool hydrodynamics is proposed that includes increased turbulence, near‐bed acceleration, and lateral flow convergence as linked aspects of convective deceleration and acceleration due to depth changes in the pool. Key Points Lateral flow convergence in pools is linked with flow deceleration A simple 2D bedform generates 3D hydrodynamic effects Alt. theories of pool formation are subcomponents of convective acceleration

The application of image velocimetry to measure surface streamflow velocities requires meticulous preparation, including surveying and securing both the existence of floating features on the water surface, and, as in every hydrometry method, appropriate hydraulic conditions (e.g., uniform flow, turbulent velocity profile, etc.). Though these requirements can be easily satisfied when all stages involved in image velocimetry are prepared and executed by specialists, this is not guaranteed when the video footage is recorded by citizens. This kind of spontaneously obtained data are frequently the only available information of extreme flood events; therefore, and despite their non-scientific origin and standardization, these data are very important for hydrology. In this study, we evaluate image velocimetry under a variety of conditions, including conditions resembling citizen videos. Furthermore, we conclude on the manual analysis as a means of verification of the accuracy of the velocity estimations. An interesting finding from the case study with non-uniform flow conditions was that the surface velocities occurring at the middle section of the river, estimated using large-scale particle image velocimetry algorithms, exhibited a significant error, whereas the manual estimation was more accurate. This finding calls for further investigation and a more careful approach in similar conditions.

This paper compares the aerodynamic characteristics of a central-spillage diverterless hypersonic inlet (i.e., bump inlet, Form 1) with a side-spillage inlet (Form 2) under on/off design conditions when faced with non-uniform inflow. Both forms are designed for a flight Mach number of 6.0 and a cruise altitude of 24.0 km. Numerical methods are introduced and validated. Integrated design results indicate that based on identical contraction ratios, Form 2 is 27.8% lower in height, 28.3% shorter in length, and 34.4% smaller in the windward projection area than Form 1. This provides the evidence that the side-spillage strategy will suppress the external drag less. Then, the aerodynamic performance is investigated under various upstream/downstream boundary conditions (inflow speed range: Mach 2.0~6.0; backpressure fluctuation range: 1~110.0 times the freestream static pressure). The evaluation methods for non-uniform flow fields are first introduced in this paper. Form 2 has a relatively stronger shock system, which allows it to suppress 4.52% more of the pressure fluctuation from the downstream combustion chamber than Form 1. The inlet start margin is widened by approximately 250% due to the self-adaptive flow spillage ability established by the side-spillage strategy. Furthermore, the compression efficiency, internal shock system, spillage ability, etc., are analyzed in detail. In summary, the side-spillage flow organization strategy has better potential for designing wide-ranging air-breathing flight vehicles.