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The elliptical hole has the potential to promote jet breakup and improve atomization and mixing quality. The flow behavior in the nozzle and the outflow characteristics have an important influence on the atomization and mixing process of the downstream fuel. Therefore, the inner cavitation flow processes and outflow characteristics for elliptical holes for scramjet engine at injection pressures of 3 MPa and 5 MPa were investigated using the Volume of Fluid (VOF) method and Large Eddy Simulation (LES). The numerical findings demonstrated that the cavitation region and vortex structures of elliptical holes mainly appeared on the long axial plane. The cavitation intensity of elliptical holes was weaker than that of the circular hole. Compared with the circular hole, the gas phase volume fraction of elliptical hole with the aspect ratio of 4 was reduced by about 22.1 and 21.1% respectively under 3MPa and 5MPa injection pressure. The application of elliptical holes inhibited the generation of cavitation and had large mass flow rate and flow coefficient. The mass flow rate of the elliptical hole with the aspect ratio of 4 was the largest, and the mass flow rate increased by about 5.1% compared with that of the circular hole. Elliptical holes showed a smaller velocity coefficient and a larger area coefficient when cavitation existed. The elliptical hole with the aspect ratio of 4 held the smallest velocity coefficient and largest area coefficient, with the difference of 12.1% and 18.9% respectively from the circular hole. Another important point was that elliptical holes enhanced the turbulent disturbance at the hole outlet, which facilitated the breakup of downstream jet. [ABSTRACT FROM AUTHOR]

Weirs of the labyrinth have some advantages including the high coefficient of the irrigation of weir and the low fluctuation of water when the flow passes over the crest of the weir. In this research, the flow rate coefficient has been investigated by changing the weir geometry in terms of wall slope, arc cycle angle, and nose length change in the upstream and downstream of each cycle of the trapezoidal arc labyrinth weir. A total of 240 tests have been performed on 16 different physical models in a channel with a width of 120 cm and a narrowing of 20 cm from each wall. All models have been compared with the control model (normal labyrinth weir) (80A). The results showed that the 80B weir with an arc cycle angle of 20 degrees and without wall slope has a better performance than other weirs. Also, the weir with an arc cycle angle and a wall slope of 20 degrees in a divergent form (D20B) in the area (Ht/P) <0.31 has a better performance than other weirs with an arc cycle angle of 20 degrees, and after this area, the weir with a wall slope of 10 degrees has performed better in divergent form (D10B). In weirs with different cycles at an arc cycle angle of 20 degrees, the labyrinth weir with 5 cycles (N5) has performed better up to the point (Ht/P)=0.36. Also, at the maximum point, the difference is 13 and 17%, respectively, compared to the 4-cycle and 3-cycle weirs. [ABSTRACT FROM AUTHOR]

In a high-altitude cruising state, boundary layer separation exists in high-lift low-pressure turbines, and inflow conditions corresponding to different blade designs can directly affect the working efficiency of low-pressure turbines. In particular, the reduced frequency of wake and free-stream turbulence intensity in an inlet flow can greatly influence boundary layer separation and transition development. In this paper, the influence of different inflow turbulence intensities and reduced wake frequencies on the development of suction surface boundary layers in high-lift low-pressure turbines under the influence of upstream wakes is studied by numerical simulations and experiments. Due to the combination of inflow free-stream turbulence intensity and reduced wake frequency, many inflow conditions can be chosen in the design process, and the unsteady influence of upstream wakes complicates the boundary layer flow. In this paper, an RBF (radial basis function)-GA (genetic algorithm) machine learning method is used to explore the optimal inlet conditions corresponding to the minimum profile loss of the Pak-B profile. The search region of the free-stream turbulence intensity is 2%–4%, and the reduced frequency of the wake is changed by changing the flow coefficient, whose variation range is 0.7–1.3. It is found that the RBF-GA machine learning method can attain an inflow condition with a lower profile loss while using the same amount of computation and effort. [ABSTRACT FROM AUTHOR]

There has always been a concern about the hydrodynamic interaction between ships in a flow field. In this study, the RANS method is utilized, and the hydrodynamic interference between two KRISO Container Ships (KCS) operating in still water with identical parameters and sailing at the same speed is investigated. Overlapping grids are used to simulate ship motion, and the VOF method is used to simulate the free surface. A KCS ship model of 1:1 size without propeller is used in the study. In order to study the change principle of the Kelvin flow field created by a single ship, the resistance coefficient and the flow field surrounding the ship are first calculated for the monohull case. Then the influence of interference between two ships is examined at various speeds and intervals and compared with the monohull case. It is discovered that the resistance coefficient of the following ship is reduced in a certain speed interval under the influence of the leading ship, where the maximum reduction can be up to 24.3%. The reason for this phenomenon may be that the wave around the following ship is superimposed on the transverse wave behind the leading ship. When the height of the wave is suppressed, the following ship's resistance is reduced. [ABSTRACT FROM AUTHOR]

Si nce we all have our own set of limitations when it comes to perceiving the world and reasoning profoundly, we are constantly met with uncertainty as a result of a lack of information (lexical impression, incompleteness), as well as specific measurement inaccuracies. It has been found that uncertainty, which shows up as ambiguity, is the root cause of complexity, which is everywhere in the real world. Most of the uncertainty in civil engineering systems comes from the fact that the constraints (parameters) are hard to understand and are described in a vague way. The ambiguity comes from a number of sources, including physical arbitrariness, statistical uncertainty due to using limited information to estimate these characteristics, and model uncertainty due to using overly simplified methods and idealized depictions of actual performances. Thus, it is better to combine fuzzy set theory and fuzzy logic. Fuzzy logic is well-suited to modelling the indeterminacy and ambiguity that results from multiple factors and a lack of data. In order to improve upon a previous predictive model, this paper uses a smart model built on a fuzzy logic system (FLS). Precipitation, temperature, humidity, slope, and land use data were all taken into account as input variables in the fuzzy model. Toprak's original explanation of the simple membership function and fuzzy rules generation technique (SMRGT) was based on the fuzzy-Mamdani methodology and used the flow coefficient as its output. The model's results were compared to available data. The following factors were considered in the comparison: 1) The maximum, minimum, mean, standard deviation, skewness, variation, and correlation coefficients are the seven statistical parameters. 2) Four types of error criteria: Mean Absolute Relative Error (MARE), Mean Square Error (MSE), Mean Absolute Error (MAE), and Root Mean Square Error (RMSE). 3) Scatter diagram. [ABSTRACT FROM AUTHOR]

In this Letter, it is shown how the determination of the effective coefficients involved in the macroscopic model for pressure driven and/or Couette flow in a rough fracture can be simplified by solving only one closure problem instead of two as originally reported in Prat et al. (Transp Porous Media 48(3):291–313, 2002. https://doi.org/10.1023/a:1015772525610). [ABSTRACT FROM AUTHOR]

We explored here the case of three-dimensional non-stationary flows of helical type for the incompressible couple stress fluid with given Bernoulli-function in the whole space (the Cauchy problem). In our presentation, the case of non-stationary helical flows with constant coefficient of proportionality α between velocity and the curl field of flow is investigated. In the given analysis for this given type of couple stress fluid flows, an absolutely novel class of exact solutions in theoretical hydrodynamics is illuminated. Conditions for the existence of the exact solution for the aforementioned type of flows were obtained, for which non-stationary helical flow with invariant Bernoulli-function satisfying to the Laplace equation was considered. The spatial and time-dependent parts of the pressure field of the fluid flow should be determined via Bernoulli-function if components of the velocity of the flow are already obtained. Analytical and numerical findings are outlined, including outstanding graphical presentations of various types of constructed solutions, in order to elucidate dynamic snapshots that show the timely development of the topological behavior of said solutions. [ABSTRACT FROM AUTHOR]

The composition and form of selenium in the soil have significant effects on the selenium content of crops. In this study, we investigated the selenium absorption pathway in plants by studying the interaction between nitrogen fertilizer and soil selenium. Our results showed that the selenium concentration enrichment factors (CEF) varied within the same region due to nitrogen fertilizer application, where they ranged from 1.33 to 5.02. The soil selenium flow coefficient (mobility factor, MF) increased with higher nitrogen application rates. The sum of the MF values for each soil layer treated with nitrogen application rates of 192 kg hm−2 and 240 kg hm−2 was 0.70, which was 64% higher than that for the control group with no nitrogen application. In the 0–20 cm soil layer, the highest summed water-soluble and exchangeable selenium and relative percentage of total selenium (12.45%) was observed at a nitrogen application rate of 240 kg hm−2. In the 20–40 cm soil layer, the highest relative percentage content of water-soluble and exchangeable selenium and total selenium (12.66%) was observed at a nitrogen application rate of 192 kg hm−2. Experimental treatment of black wheat with various concentrations of sodium selenite showed that selenium treatment at 50 μmol L−1 significantly increased the reduced glutathione (GSH) levels in the leaves and roots of seedlings, where the GSH contents increased by 155.4% in the leaves and by 91.5% in the roots. Further analysis of the soil–black wheat system showed that nitrogen application in selenium-rich areas affected the soil selenium flow coefficient and morphological composition, thereby changing the enrichment coefficient for leaves (0.823), transport capacity from leaves to grains (–0.530), and enrichment coefficient for roots (0.38). These changes ultimately affected the selenium concentration in the grains of black wheat. [ABSTRACT FROM AUTHOR]

Debris flow is a typical natural disaster in the middle reaches of the Dadu River, which seriously threatens the safety of life and property of local residents. However, there is currently a lack of a comprehensive analysis methods applicable to the blockage of river channels by debris flow in the Dadu River basin, limiting disaster prevention and mitigation in this area. Based on previous large-scale model tests carried out in the middle reaches of the Dadu River, the debris flows are divided into dam-type debris flows and submerged debris flows. The calculation formulas for the maximum travel distance of the two kinds of debris flows entering the river are obtained via theoretical derivation. The formulas for calculating the length and volume of debris flow accumulation are derived, and the relationship between the debris flow loss coefficient and river blocking degree in the middle part of the Dadu River is analyzed. An identification method of river blocking by debris flow is put forward in this study. By calculating the maximum blocking degree, S (the ratio of the maximum driving distance of the debris flow to the width of the river), and the volume of the source materials needed to form a debris flow dam under the conditions that the debris flow does not reach the opposite bank (V1), reaches the opposite bank but does not block the river (V2), and reaches the opposite bank (V3), the form of debris flow blocking the river is distinguished. When S = 1, V > V3, complete blockage occurs; when S = 1, V > V2, the river is mostly blocked; when S < 1, V > V1, the river is half-blocked. This study established an identification method of river blocking by debris flow, providing a basis for early warning for river blocking and disaster prevention in the middle reaches of the Dadu River. [ABSTRACT FROM AUTHOR]

In this paper, the collective motion of viscous drops is investigated in terms of a porous medium setting. We assume that the interface of each of the drops is fully covered with a stagnant layer of surfactant in an arbitrary unsteady Stokes flow with low surface Péclet number limit. The effect of the interfacial slip coefficient on the behavior of the flow fields is also considered. The modeling of the physical processes leads to a system of parabolic partial differential equations (PDEs) with interfacial boundary conditions. We have proposed a model in a micro--macro scale setting. We have shown the existence of a unique positive weak solution of such system. We have also obtained a homogenized (upscaled) model of the system via two-scale convergence and boundary unfolding method. [ABSTRACT FROM AUTHOR]

We present a review of published experimental measurements on anisotropic flow in heavy-ion collisions. Flow coefficients v n are presented for charged and identified hadrons at various beam energies ranging from s NN = 7. 7 GeV to 200 GeV at the Relativistic Heavy Ion Collider (RHIC) and s NN = 2 7 6 0 GeV at the Large Hadron Collider (LHC). We present v 1 and its slope d v 1 ∕ d y and discuss possible first-order Quantum chromodynamics (QCD) phase transition. v 1 of particles containing heavy quarks (Charm quarks) is also discussed to illustrate the effect of the magnetic field produced in relativistic heavy-ion collisions. We also present flow harmonics ( v 2 , v 3 and v 4 ) for inclusive charged and identified hadrons. We compare the charged particle v n coefficients with hydrodynamics to study and constrain initial conditions in the transport models. The results of identified particle v 2 from ideal and viscous hydrodynamics are discussed to understand the dynamics and mechanism of particle production in high-energy nuclear collisions. [ABSTRACT FROM AUTHOR]

New polymeric pipes have been used to overcome difficulties created by metal pipes in gas transmission lines such as corrosion and leakage. In this work, diffusion and solubility cells are designed to determine the diffusivity and possible leakage of methane and ethane gases in the glass-reinforced epoxy (GRE) composite. A composite sample with a diameter of 5.95 mm and thickness of 1.40 mm to determine the diffusivity and a composite powder to estimate the gas solubility are used. The experiments are done under temperatures varied from 25 to 40 ℃ and a pressure of 20 bar. The results show that the diffusivity of both gases increases with increasing temperature; while gas solubility decreases. The highest diffusion coefficient of methane and ethane are observed at 8.23 × 10−11 and 7.94 × 10−11 m2/s at 40 ℃, respectively. Moreover, novel correlations for estimating gas diffusion coefficient and mass flow rate in terms of temperature are developed based on the experimental data with the correlation coefficients (R2) of 0.98 and 1 and the average relative error percent (AREP) less than 4.5% and 0.5%, respectively. Interestingly, CFD (Computational fluid dynamics) results show a good consistency with experimental data for gas concentration profiles through the composite with AREP ranges of 1.95–15.78%. [Display omitted] [ABSTRACT FROM AUTHOR]

The Chiral Magnetic Wave (CMW) phenomenon is essential to provide insights into the strong interaction in QCD, the properties of the quark-gluon plasma, and the topological characteristics of the early universe, offering a deeper understanding of fundamental physics in high-energy collisions. Measurements of the charge-dependent anisotropic flow coefficients are studied in Pb-Pb collisions at center-of-mass energy per nucleon-nucleon collision s NN = 5.02 TeV to probe the CMW. In particular, the slope of the normalized difference in elliptic (v2) and triangular (v3) flow coefficients of positively and negatively charged particles as a function of their event-wise normalized number difference, is reported for inclusive and identified particles. The slope r 3 Norm is found to be larger than zero and to have a magnitude similar to r 2 Norm , thus pointing to a large background contribution for these measurements. Furthermore, r 2 Norm can be described by a blast wave model calculation that incorporates local charge conservation. In addition, using the event shape engineering technique yields a fraction of CMW (fCMW) contribution to this measurement which is compatible with zero. This measurement provides the very first upper limit for fCMW, and in the 10–60% centrality interval it is found to be 26% (38%) at 95% (99.7%) confidence level. [ABSTRACT FROM AUTHOR]

We show that if drift coefficients of Arratia flows converge in L 1 (R) or L ∞ (R) then the 1-point densities associated with these flows converge to the density for the flow with the limit drift. The main result is proven by providing a representation of the probability of coalescence in the flow as a solution to a PDE and applying the perturbation theory. [ABSTRACT FROM AUTHOR]

Multi-way spool valves (MWSVs) with K-shape notches (KSNs) provide advantages such as improvement of the actuator speed control, micro-action, and response performance. However, the pressure drop (PD) associated with the energy consumption is larger of MWSVs under the high-pressure and large-flow condition. Meanwhile, extremely complex flow coefficient and multi-parameter, highly coupled KSNs are the chief factors restricting the flow-pressure characteristics exploration and optimisation design of MWSVs. To address these problems, complete numerical research and experiment are performed in this study, especially concerning the method of MWSV flow-pressure characteristics modelling, and surrogated model-based optimal design of KSN structures. First, the relationships between KSN structure parameters and flow-pressure properties of MWSV are modelled on the innovative discharge area parameter model (DAPM) and response surface methodology (RSM) (RSMDPAM) using the CFD dataset. Second, to reduce the PD combining the flow control performance, surrogate model-based optimisation design is addressed. During optimisation, six KSN structure parameters are chosen as design variables, PD and flow area relative deviation (FARD) are selected as objective functions, and the RSM is employed as the projected model. Depended on the created surrogate model, the non-dominated sorting genetic algorithm (NSGA-II) is established to search for the optimal KSN structure. To certify the performance of the optimisation, flow field characteristics are analysed. The results demonstrate that the proposed RSM-DAPM-RSM model achieves reliable prediction for PD and FARD with a great correlation coefficient (0.9757 and 0.9946). The average PD reduces as much as 7.23% while the FARD is only 1.28%. Moreover, the region of low-pressure, highvelocity, and high-turbulent kinetic energy in the flow field are reduced. The proposed framework enhances the performance in KSN spool optimisation and could be applied to other kinds of notches. [ABSTRACT FROM AUTHOR]

The forward-curved multi-blade centrifugal fan is widely used in the ventilation and household appliance industries with limited space due to its small size factor, high pressure coefficient, and large outlet flow coefficient. Conventional centrifugal fan structural designs rely on empirical data, resulting in drawbacks during usage such as low airflow velocity, high noise levels, and high energy consumption. In order to optimize fan structure, enhance aerodynamic performance, and seek new, effective approaches for energy efficiency and emissions reduction, this paper focuses on a combined design method that integrates scroll line design with aerodynamic performance and noise control. The goal is to propose a noise prediction and analysis method for multi-blade centrifugal fans, addressing the design contradiction between optimal fan functionality and minimal noise within limited design dimensions. The dynamic radial basis function method is introduced to investigate the geometric parameters of the scroll line, utilizing coherence analysis to identify the reasons for insufficient aerodynamic performance and noise reduction measures. Through the research, it is found that unreasonable design leads to a large turbulent vortex region within the blade passage and internal flow field, particularly involving circulation and backflow, which significantly reduces the fan's aerodynamic performance and operational efficiency. The design incorporates a composite scroll with a logarithmic spiral and circular arc integrated into one, and algorithm-based optimization of the scroll tongue, facilitating the transition of turbulence at the scroll outlet and the gap between the scroll tongue and impeller. Numerical results show an increase in airflow of 3.04 m3/min and a noise reduction of 3.79%. This indicates that the composite scroll design with a logarithmic spiral plays a dominant role in accelerating the aerodynamic performance of the scroll and reducing noise radiation. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation of the flow pattern regime and unsteady characteristics of ventilated cavities with different headform shapes. The test model consists of a removable headform with three different forebodies (the conical, the blunt, and the hemispherical) and a common cylinder rear body. Experiments are conducted in a closed-loop cavitation tunnel. First, the flow pattern regimes on the ventilated cavity for different headforms are discussed in detail, and the dimensions of several flow patterns are measured. The results show that the cavity dimension and the regime are strongly dependent on the headform shape, and all typical flow patterns are introduced by schematic illustrations. Second, the ventilation hysteresis that happened during the flow pattern transition is pointed out. A quantitative gas leakage model is employed to explain the cause of hysteresis and flow pattern transition, and the results show the Strouhal number for different headforms is approximately ∼0.21. However, the blunt presented stronger gas leakage with a large constant parameter, K = 0.80. Finally, the unsteady characteristics of the ventilated cavity around different tested headforms are involved through descriptions of developments of the recirculating vortex and transparent cavity. In addition, an estimated cavitation number is applied to investigate the unsteady characteristics, and the maximum cavitation number and the strongest characteristic are obtained by the blunt headform due to the large drag coefficient and strong flow separation. [ABSTRACT FROM AUTHOR]

The trace of the polymer conformation tensor in numerical simulations is bounded by applying a logarithmic transformation to the elastic force in the finitely extensible nonlinear elastic-Peterlin model. This method, called elastic stress logarithmic transformation (EL), is combined with the artificial diffusion (AD) and square-root conformation reformulation (SRCR) methods to establish EL-AD and EL-SRCR methods, respectively. The accuracy and stability of these methods have been investigated by conducting direct numerical simulations of viscoelastic laminar flows around a circular cylinder at a Reynolds number Re = 100, considering a wide range of rheological parameters: the maximum polymer extensibility L = 10 and 100, and the Weissenberg number W i = 1 − 80. Specifically, effects of artificial diffusion coefficients measured by dimensionless Schmidt number S c c = 10 − 10 6 on the flow are studied. The results indicate that the EL method can effectively ensure the boundedness and accuracy of the conformation tensor trace, making the EL-AD method a valuable modification of the AD method for simulations with larger L and Wi. The impact of the polymer stress diffusion on the simulation is complex. It can stabilize the simulation by reducing sharp gradients and peak positions of elastic stress. However, inappropriate artificial diffusion coefficients lead to flow artifacts when L is large (L = 100). One consequence is an amplification of the solid-like phenomenon caused by polymer near the upstream stagnation point of the cylinder. Another consequence is an enhanced suppression of vortices by polymer downstream of the cylinder. The challenge in determining a suitable AD coefficient emphasizes the superiority of the EL-SRCR method in terms of stability and accuracy. [ABSTRACT FROM AUTHOR]

Large resources of thermal and industrial waters at a temperature of 100–150°С can be employed to generate electricity in both a single-circuit thermal cycle with direct usage of natural steam in condensing turbines and a double-circuit cycle with a low-boiling working fluid. Both options require high capital expenditures for their implementation. A new power-generation method on the basis of low-grade heat is to install a full-flow hydro-steam turbine (HST), which utilizes the heat of separated liquid from a geothermal station or the heat of industrial waters, in a single-circuit thermal cycle. Capital expenditures for these units are much lower since special equipment for preparation of the working fluid is not required. The efficiency of a hydro-steam turbine is directly related to the efficiency of its main element, which is the Laval nozzle. Designing this turbine requires reliable data on the performance of a Laval nozzle with a high expansion ratio when it operates on highly subcooled water. Such information can only be obtained experimentally since this region of operation of Laval nozzles has been poorly studied as of yet. To determine the required characteristics of the nozzles, an experimental setup was designed and manufactured with a set of Laval nozzles, including nozzles with different opening angles of the diverging section and nozzles with an oblique cut. The working fluid was water under conditions close to the operating conditions in an HST. The results are presented of the experimental study of Laval nozzles in a wide range of expansion ratios for operation on boiling water. The experiments were performed at different pressures downstream of the nozzle, and their results were compared with previously obtained experimental data. The experimental setup and design features of the nozzle are described. The experimental data on the flow coefficient, velocity coefficient, expansion ratio, initial conditions, nozzle shapes, and size effect, on which the conclusions made are based, have been analyzed. Characteristics have been found that enable us to predict the efficiency of a reaction hydro-steam turbine and properly calculate its output. [ABSTRACT FROM AUTHOR]

We establish sharp relations between several regularity coefficients for flows generated by non-autonomous differential equations. We verify that these relations are sharp by showing that all possible values of the regularity coefficients satisfying these relations are attained by some linear equation with bounded piecewise-continuous coefficient matrix. In addition, we introduce two new regularity coefficients and we obtain sharp relations between these and other coefficients. [ABSTRACT FROM AUTHOR]

In modern turbofan engines, the bypass section of the fan stage alone provides the majority of the total thrust required in cruise, and the size of the fan has a considerable effect on the overall engine weight and nacelle drag. Thrust requirements in different parts of the flight envelope must also be satisfied together with sufficient margins towards stalling. An accurate description of the interdependencies between the relevant performance and design attributes of the fan stage alone—such as efficiency, surge margin, fan-face Mach number, stage loading, flow coefficient, and aspect ratio—are therefore necessary to estimate system-level objectives such as mission fuel burn and the direct operating cost with enough confidence during the conceptual design phase. The contribution of this study is to apply a parametric optimization approach to the conceptual design of fan stages for low specific thrust turbofans based on the streamline curvature method. Trade-offs between fan stage attributes for Pareto-optimal solutions are modeled by training Kriging surrogate models on the results from the parametric optimization. A case study is provided in the end to demonstrate the potential implications of including a higher level of fan-stage parameter interdependency in an engine systems model. Results implied that being able to predict the rotor solidity required to maintain a given average blade loading—in addition to stage efficiency—is of significant importance when it comes to evaluating the trade-off between engine weight and thrust-specific fuel consumption. [ABSTRACT FROM AUTHOR]

[Objective] To provide reference for expanding the applicability of weir-flume combination facility, the influence of outlet width of measuring flume on hydraulic performance and flow measurement of weir-flume combination facility was studied. [Method] Under different flow conditions (5-71 L/s), 35 sets of hydraulic performance tests with three measuring flume outlet widths (6 = 25, 35 and 45 cm) were carried. The influence of outlet width on water surface line of middle vertical plane and Froude number (Fr) along the flume was analyzed through the changes of water depth and vertical average velocity of 30 measuring points in the middle vertical plane. Then, the flow thresholds of in-groove flow and weir flow were determined. According to the correlation between inlet-flow (Q) and water depth of measuring point in the flume, the influence of outlet width on the discharge coefficient was analyzed and the flow formula with different outlet widths was established. [Result] Under three different outlet widths, the water depth of the middle vertical plane and Fr showed similar variations along the flume. The water depth of the middle vertical plane was stable in the upstream section and dropped to the thin water layer gradually after entering the measuring flume. Fr was relatively stable in the upstream section (0.1 -0.2) and increased to the maximum value (1.2-1.5) gradually after entering the flume, and the increasing rate increased along the flume. The water depths in the upstream section and in the measuring flume decreased with the increase of outlet width. The water depths in the outlet section, thin water layer and backwater area were not greatly affected by outlet width. The Fr from the upstream section to the torsional transition inside the measuring flume increased with the increase of outlet width, but that of the trapezoidal narrow section decreased with the increase of outlet width. Under same outlet widths, the flow coefficient of the in-flume flow increased with the increase of flow rate, while the flow coefficient of the weir flow decreased. Under same relative acting heads, the discharge coefficient of the in-flume flow decreased with the increase of outlet width, while that of the weir flow increased. Based on the established flow formulas under outlet widths of three measuring flumes, relative errors between calculated and measured flow values were all within 2%, expanding the application scope of weir-flume combination facility. [Conclusion] The outlet width of measuring flume had important influence on water depth in upstream and measuring flume. The increase of outlet width increased the flow threshold and overflow capacity of weir-flume combination facility and pushed the critical depth section downstream. [ABSTRACT FROM AUTHOR]

The karst area in China accounts for about 20% of the total land area. The karst groundwater is rich in resources and is an important source of production and living water in karst areas. The annual average rainfall in karst areas of Southwest China exceeds 1,200 mm, but the time distribution of rainfall is extremely uneven, which is likely to cause drought and flood disasters, and hence will seriously restrict the production and life of local people. The karst vadose zone has the function of conserving and regulating groundwater. Therefore, it is of great significance to study the influence mechanism of water flow attenuation process and regulating capacity in the karst vadose zone for rational development and utilization of karst water resources. The high heterogeneity and the anistropy of the karst aquifer system often make the karst vadose zone form a drainage network and become a channel for groundwater. A karst vadose zone is mainly composed of soil zone, epikarst zone and transfer zone, of which the soil zone and the epikarst zone are main water storage space. The water storage function of karst vadose zone is related to the dynamic regulation of groundwater resources in the epikarst zone. Rainfall infiltration is transferred from the transfer zone to the phreatic aquifer through the regulating and diversion of the epikarst zone. In the karst vadose zone, the low flow velocity in diagenetic pores, micro fissures and carbonate rock matrix shows its feature of slow flow, while the fast flow velocity in large fissures and sinkholes is characterized by rapid flow. Therefore, the heterogeneity of karst aquifer system and the complexity of runoff path in karst vadose zone increase the difficulty of the study on groundwater flow process. In previous laboratory tests on water flow attenuation process and regulating capacity in karst areas, a two-dimensional fissure-conduit model built of polymethyl methacrylate was mostly used. Although it can simplify the structure of aqueous medium, it is quite different from the actual structure, and the soil zone is not considered. Meanwhile, the current studies on the regulating capacity of karst areas are mainly focused on the epikarst zone, and the studies on the influence of the transfer zone on the regulating capacity are very few. In this study, a laboratory-scale three-dimensional model of karst vadose zone was built with limestones. The attenuation curve was analyzed by superposed exponential decay equation, and the regulating coefficient was calculated by formula. The influence of rainfall intensity, fissure development degree and thickness of transfer zone on the attenuation process and regulating capacity of water flow in karst vadose zone were explored. In this study, three tests were set up to explore the influence of the above factors on the attenuation process of water flow and the regulating capacity in karst vadose zone. In Test 1, five control groups with different rainfall intensities were designed, including 5 mm•h-1, 10 mm•h-1, 20 mm•h-1, 30 mm•h-1 and 50 mm•h-1, and the attenuation coefficient and regulating coefficient under the corresponding rainfall intensity were obtained respectively. The analysis of test data shows that the greater the rainfall intensity is, the faster the attenuation speed is, and the influence on the attenuation coefficient of fast flow is greater than that on the attenuation coefficient of slow flow. When the structure of karst vadose zone is fixed, the regulating capacity gradually decreases with the increase of rainfall intensity, but this effect is limited: when the intensity increases to a certain extent, the regulating coefficient is basically unchanged. In Test 2, the number of fissures in the transfer zone is designed as 1, 2, 3, 4 and full fissures. It is concluded that the attenuation speed of fast flow accelerates and the attenuation speed of slow flow slows down with the increase of fissure development in the transfer zone. The data also demonstrates that the higher the fissure development is, the weaker the regulating capacity of the aquifer system is. In Test 3, five groups of control tests with different thicknesses of transfer zone were designed, and the thickness increased from 40 cm to 120 cm, with a difference of 20 cm between each group. Results indicate that the increase of the thickness will lead to the decrease of the attenuation coefficient and the increase of the regulating coefficient, but the influence of thickness on the latter is not very obvious. [ABSTRACT FROM AUTHOR]

In rural catchments, villages often feature their own, separate urban water infrastructure, including combined sewer overflows (CSOs) or wastewater treatment plants (WWTPs). These point sources affect the water quantity and quality of the receiving low order streams. However, the extent of this impact is rarely monitored. We installed discharge and water quality measurements at the outlet of two small, neighbouring headwater catchments, one that includes a village, a WWTP, and two CSOs, while the other is predominantly influenced by agricultural activities. We also deployed electrical conductivity (EC) loggers at the CSOs to accurately detect discharge times. Discharge from the WWTP and CSOs led to higher peak flows and runoff coefficients during events. Less dilution of EC and increasing ammonium-N (NH4 − N) and ortho-phosphorus (oPO4 − P) concentrations indicate a significant contribution of poorly treated wastewater from the WWTP. During CSO events, water volumes and nutrient loads were clearly elevated, although concentrations were diluted, except for nitrite-N (NO2 − N) and particulate phosphorus (PP). Baseflow nitrate-N (NO3 − N) concentrations were diluted by the WWTP effluent, which led to considerably lower concentrations compared to the more agriculturally influenced stream. Concentrations of oPO4 − P, NH4 − N, and NO2 − N, which are most likely to originate from the WWTP, vary throughout the year but are always elevated. Our study shows the major and variable impact rural settlements can have on stream hydrology and water quality. Point sources should be monitored more closely to better understand the interaction of natural catchment responses and effects caused by sanitary infrastructure. [ABSTRACT FROM AUTHOR]

In this paper, the three dimensional LES method was used to generate a typical turbulent wind field. Three streamlined box girders with three different aspect ratios were adopted to investigate the effects of aspect ratios on the force coefficients and flow separation characteristics with different angles of attack. The results show that the aspect ratio has significant effects on the force coefficients of the streamlined box girder, and the larger the aspect ratio is, the larger the lift coefficient is. For the flow separation characteristics, as the aspect ratio increases, the spacing of wake vortex is shortened and the wake vortex dissipation rate is accelerated. [ABSTRACT FROM AUTHOR]

The key function of lubricants is to reduce the friction, wear, and heat between the parts that are in contact with each other. The main applications of the lubricants are to control temperature, and reduction in wear and corrosion of the machinery. Keeping in mind the importance of lubrication and its applications in varied machines. The goal of this research is to inspect the heat transmission impact in the magnetohydrodynamic flow of Jeffrey liquid near a stagnation point through a lubricated surface. Lubrication is accomplished by a shear-thinning liquid. The velocity, continuity, and shear stress, amalgamated with power-law fluids, are used to develop interfacial conditions. The exclusivity of the anticipated model is the inclusion of variable thermal conductivity and diffusion coefficients in the existence of homogeneous-heterogeneous reactions. Using the Keller–Box finite-difference approximation approach, the numerical results are accomplished. The outcomes are portrayed and tabulated in the form of diagrams and tables, respectively. It is witnessed that a greater magnetic field affects the fluid flow velocity and the drag force coefficient. Moreover, it is also inferred that the heat transfer rate dwindled for the greater thermal conductivity parameter. Authentication of the presented model is also part of this investigation. [ABSTRACT FROM AUTHOR]

Boesch, Li, and Suffel were the first to identify the existence of uniformly optimally reliable graphs (UOR graphs), graphs which maximize all-terminal reliability over all graphs with n vertices and m edges. The all-terminal reliability of a graph, and more generally a graph's all-terminal reliability polynomial R (G ; p) , may both be obtained via the Tutte polynomial T (G ; x , y) of the graph G. Here we show that the UOR graphs found earlier are in fact maximum graphs for the Tutte polynomial itself, in the sense that they are maximum not just for all-terminal reliability but for a vast array of other parameters and polynomials that may be obtained from T (G ; x , y) as well. These parameters include, but are not limited to, enumerations of a wide variety of well-known orientations, partial orientations, and fourientations of G ; the magnitudes of the coefficients of the chromatic and flow polynomials of G ; and a wide variety of generating functions, such as generating functions enumerating spanning forests and spanning connected subgraphs of G. The maximality of all of these parameters is done in a unified way through the use of (n , m) Tutte polynomial posets. [ABSTRACT FROM AUTHOR]

Understanding the skin friction in an axisymmetric turbulent boundary layer (ATBL) flow is a key to designing and optimising the flow past axisymmetric bodies, for example, a rocket engine nozzle and a submarine hull. In this study, we propose a universal law of the skin-friction coefficient in an ATBL flow. The flow is steady and fully developed with a zero pressure gradient. The governing equation for the ATBL flow is derived by methodically applying the boundary layer approximation. Subsequently, the scaling law of the Reynolds shear stress, caused by turbulent eddies, at the surface tangential to the wall roughness summits is derived by incorporating the role of transverse curvature. The skin-friction coefficient in a smooth ATBL flow is found to depend on two parameters, namely, the Reynolds number based on the cylinder radius, Rea , and the ratio of boundary layer thickness to cylinder radius, δ / a. The analysis predicts a simple form of the skin-friction coefficient as ${C_f} = 4.56 \times {10^{ - 2}}{[R{e_a}\ln (1 + \delta /a)]^{ - 1/4}}$ , which agrees satisfactorily with the available experimental data and the numerical simulations in all the axisymmetric flow regimes. The proposed law, in the limit of infinite radius, is consistent with the classical law of the skin-friction coefficient in a plane turbulent boundary layer flow as ${C_{f0}}\sim Re_\delta ^{ - 1/4}$ , where Reδ is the Reynolds number based on the boundary layer thickness. This study reveals that, for δ / a  < 1, the relative skin-friction coefficient, $({C_f} - {C_{f0}})/{C_{f0}}$ , follows a linear law with δ $/$ a. [ABSTRACT FROM AUTHOR]

Abstract In order to reduce the pressure loss of the nozzle and boost the efficiency of jet impingement heat transfer, this article takes the flow coefficient as the target variable and uses response surface methodology to optimize the straight cone nozzle’s internal structure. The optimal structural parameters obtained are as follows: the contraction angle is 30° and the lengths of the contraction section and the outlet section are 5 and 2 times of the outlet diameter, respectively. Besides, the influence of nozzle structural parameters on the heat transfer characteristics of a single water jet impinging on a high-temperature steel plate are simulated by ANSYS-Fluent. According to the results, the optimized nozzle has the largest flow coefficient, and the average Nusselt number on the steel plate is also the largest under the same inlet pressure. [ABSTRACT FROM AUTHOR]

Low-pressure water mist fire extinguishing systems are a cost-effective and highly reliable option for fire protection. However, they have not yet seen widespread use in urban underground utility tunnels. To validate the fire extinguishing effectiveness of the system in cable fires within urban utility tunnels and to identify the key factors influencing its efficiency, a scaled-down test platform for low-pressure water mist fire extinguishing in utility tunnels was constructed, and a series of fire extinguishing tests was conducted. The test results demonstrate that low-pressure water mist can rapidly and effectively extinguish cable fires in utility tunnels, with the quickest fire extinguishing time of 7 s. Within 50 s of activating the system, the internal temperature of the tunnel can be reduced from 650 °C to 40 °C. Among the influencing factors, the pressure and nozzle flow coefficient have a significant impact on the fire extinguishing efficiency, while nozzle spacing has a relatively smaller effect. Thus, when the nozzle spacing meets the requirement of "no dead zones", priority should be given to increasing the pressure and nozzle flow coefficient. [ABSTRACT FROM AUTHOR]

• Extensive experiments for R454C through an EEV were carried out and studied. • Two semi-empirical correlations were developed for mass flow rate prediction. • The proposed correlations can predict 95% of the experimental results within 10%. • A potential relation between molar mass and mass flow coefficient was observed. The use of electronic expansion valves (EEVs) in heat pump systems has seen a rapid increase in recent years due to their advantages such as fast response, accurate control, and ability to improve seasonal performance. Modeling of the refrigerant flow characteristics through EEVs is needed during design for optimizing system performance and operation. Previous studies have not led to any generalized correlations for EEVs that accurately predict performance for different refrigerants. When working with a new refrigerant and/or EEV, it is necessary to perform mass flow measurements for the EEV over a wide range of operating conditions that are then used to develop and validate a refrigerant and EEV specific correlation. R454C, a low-GWP refrigerant mixture, is gaining attention as a potential replacement for R404A and R410A systems. However, there is currently no available EEV experimental data or correlation specifically for R454C in the literature. The objective of this paper is to present experimental results and characterization of R454C flowing through an EEV in a heat pump split system across a wide range of operational conditions. The impacts of valve opening, subcooling degree and inlet pressure on mass flow rate though the EEV were investigated. Two semi-empirical correlations were developed that map the experimental data based on the Buckingham π theorem and a polynomial function. Both mapping methods predicted mass flow rate for test data within 10%. The Buckingham π correlation was slightly more accurate. Both correlations were developed to enable mass flow rate predictions for R454C passing through EEVs with different valve sizes. Finally, a relationship between refrigerant molar mass and mass flow coefficient was observed that could be useful in developing a general EEV correlation that can be applied for different refrigerants. However, further investigation is needed to validate this relationship. [ABSTRACT FROM AUTHOR]

The impact of dead space volume on the working processes of a positive-displacement piston hybrid power machine (PDPHPM) with two suction valves is investigated. Due to the fact that the process of back expansion in this machine proceeds with variable gas mass, an expression for determining the volume coefficient at variable mass of expanding gas is obtained. The numerical experiment carried out using the previously developed mathematical model established the effect of the dead space volume on the instantaneous integral characteristics of the machine. It is shown that an increase in the dead space volume leads to increase in the duration of the expansion process (despite a decrease in the mass of the expanding gas), a decrease in the coolant consumption, a significant decrease in the flow coefficient, and a slight decrease in the indicator isothermal efficiency. [ABSTRACT FROM AUTHOR]

The flow inside the orifices in diesel injector largely determines the injection characteristics, which further affects the performance of the diesel engine. In this paper, numerical simulation is conducted to characterize the fuel flow with characteristics of two-phase cavitation, high speed, high pressure, high turbulence intensity, and high viscosity in two crucial orifice locations. The OZ orifice is selected as a benchmark to select the appropriate turbulence model and cavitation model. The simulation results from different turbulence and cavitation models are analyzed, and the combination of the realizable k–ε turbulence model and the Zwart–Gerber–Belamri cavitation model proves to be superior. Then, based on the validated models, the compressibility and non-isothermal characteristics of the fuel and two geometric parameters of the nozzles in an injector are emphatically discussed to depict the cavitation flow. The results suggest that the compressibility and non-isothermal characteristics of fuel affect the mass flow rate, fuel flow velocity, and cavitation extent within the orifices with a maximum deviation of the mass flow rate of 7.1%. However, their influence on the orifice flow coefficient is relatively minor with a maximum deviation of 0.8%. The mass flow rate and flow coefficient are both positively correlated with the rounded edge radius and taper coefficient. A greater rounded edge radius and taper coefficient can lead to a better fuel flow capacity in the nozzle orifice. [ABSTRACT FROM AUTHOR]

Through comparing with the tandem circular and elliptic cylinders with the same characteristic dimensions, the behavior of flow and flow-induced noise generated around the tandem seal-vibrissa-shaped cylinder is studied based on delayed detached-eddy simulation model and acoustic analogy approach. The co-shedding pattern of flow developed around the tandem cylindrical-like bars is investigated. The spatial modes, mode energy, and mode coefficients of turbulent flow around the geometries are analyzed through spectral proper orthogonal decomposition. Results show that the lift fluctuations of downstream bar are stronger than those of upstream bar, and more aerodynamic noise is radiated from the downstream bar than from the upstream bar. The alternative arrangement of nodal and saddle planes of seal-vibrissa-shaped cylinder introduces three-dimensional flow separations and suppresses the shear layer interactions, inhibiting the regular vortex shedding of Kármán vortex street occurring in the tandem cylinder wake. The reversed vortex shedding generated by two adjacent saddle surfaces in the wake of seal-vibrissa-shaped cylinder balances the lateral force and mitigates the lift fluctuations greatly, thereafter reduces the aerodynamic noise generated by wall pressure fluctuations introduced by unsteady fluctuating forces exerting on the surfaces of geometries. Compared to the tandem circular and elliptic cylinders, the good noise reduction effect with sound pressure level reduced at main frequency range has been achieved from the tandem seal-vibrissa-shaped cylinder. The calculated spectra and amplitude levels of aerodynamic noise agree well with the experimental measurements from the anechoic wind tunnel, verifying the accuracy of the numerical simulations. [ABSTRACT FROM AUTHOR]

The influence of inducer rotation speed on the propagation characteristics of rotating cavitation and on the unsteady characteristics of cavitation in rotating cavitation and cavitation surge were examined using a three-bladed inducer, which is named THK inducer, to develop the rocket engine turbopump that can operate stably over a wide operating range. The novel point of the paper is focusing on the cavitation itself, which is the cause of cavitation instabilities. The paper conducted two types of experiments using an inducer and single hydrofoils, and the dimensional and nondimensional unsteady characteristic, which is the frequency of unsteady cavitation and the Strouhal number, were evaluated. Three types of rotating cavitation and cavitation surge were observed in the inducer. For a given cavitation number, the Strouhal number of rotating cavitation and the frequency of unsteady cavitation in cavitation surge are independent of the inducer rotation speed, respectively. The characteristic of rotating cavitation corresponds to that of cavitations arising in hydrofoils, but its characteristic of cavitation surge does not correspond. The dynamic characteristic of cavitation compliance in cavitation surge is similar to that of several rocket engine turbopumps. Therefore, it was proved that rotating cavitation is a cavity oscillation and cavitation surge is a system oscillation. Additionally, in a flow field with the same flow coefficient and different impeller rotation speed, the unsteady characteristics of cavitation instabilities are equal if the cavitation number is equal, which is named the "similarity law of cavitation number on cavitation instability.". [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mangroves are a natural feature that enhance the resilience of natural and built coastal environments worldwide. They mitigate the impacts of hurricanes by dissipating energy from storm surges and waves, as well as reducing wind speeds. To incorporate mangroves into storm surge simulations, surface roughness parameters that accurately capture mangrove effects are required. These effects are typically parameterized using Manning's n bottom friction coefficient for overland flow and aerodynamic roughness length (z0) for wind speed reduction. This paper presents the suggested values for these surface roughness parameters based on field observation and a novel voxel-based processing method for laser scanning point clouds. The recommended Manning's n and z0 values for mangroves in southwest Florida are 0.138 and 2.34 m, respectively. The data were also used to retrain a previously developed random forest model to predict these surface roughness parameters based on point cloud statistics. The addition of the mangrove sites to the training data produced mixed results, improving the predictions of z0 while weakening the predictions of Manning's n. The paper concludes that machine learning models developed to predict environmental attributes using small datasets with predictor features containing subjective estimates are sensitive to the uncertainty in the field observations. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Soil Sciences & Agricultural Engineering is the property of Egyptian National Agricultural Library (ENAL) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study conducts a series of undrained cyclic shear tests on saturated coral sand with different initial relative densities (Dr) subjected to a 90° jump rotation of the principal stress with various initial orientations. Considering liquefiable coral sand as a fluid, an important finding is that the variation in the apparent viscosity with the number of cycles is significantly affected by Dr, the effective mean principal stress ( p 0 ′ ), cyclic stress ratio, cyclic loading path, and cyclic loading frequency. The average flow coefficient (κ) is introduced to describe the fluidity of saturated coral sand under cyclic loading by considering the variation in the shape of the stress–strain rate curve. A positive exponential correlation is observed between κ and the excess pore water pressure (EPWP) ratio (ru) under the given cyclic loading modes. Another significant finding is that the solid–liquid phase change time is the turning point of the apparent viscosity and the average flow coefficient gradients with ru. The inversion point's EPWP ratio is approximately 0.9, defined as the EPWP ratio during the solid–liquid phase transformation (ruth). The ruth value is not affected by cyclic loading mode, p 0 ′ , and Dr. [ABSTRACT FROM AUTHOR]

Streamflow is a vital component of the global water cycle. Long-term streamflow observations are required for water resources planning and management, hydroclimatic extremes analysis, and ecological assessment. However, long-term streamflow observations for the Indian-Subcontinental (ISC) river basins are lacking. Using meteorological observations, state-of-the-art hydrological model, and river routing model, we developed hydrological model-simulated monthly streamflow from 1951–2021 for the ISC river basins. We used high-resolution vector-based routing model (mizuRoute) to generate streamflow at 9579 stream reaches in the sub-continental river basins. The model-simulated streamflow showed good performance against the observed flow with coefficient of determination (R2) and Nash-Sutcliffe efficiency (NSE) above 0.70 for more than 60% of the gauge stations. The dataset was used to examine the variability in low, average, and high flow across the streams. Long-term changes in streamflow showed a significant decline in flow in the Ganga basin while an increase in the semi-arid western India and Indus basin. Long-term streamflow can be used for planning water management and climate change adaptation in the Indian sub-continent. [ABSTRACT FROM AUTHOR]

This paper presents an accurate prediction of surface drag, pressure coefficient and flow transition around a symmetric airfoil design through the implementation of finite element discretization. Skin friction coefficient has been analyzed at different Reynolds number and at various angles of attack for NACA0012 airfoil design. The transition from laminar to turbulent flow significantly impacts the separation of the boundary layer and skin friction of the airfoil, ultimately affecting its aerodynamic characteristics. The pressure distribution around the surface of NACA0012 has also been computed at several Reynolds number and different attack angles using higher order triangular meshes. Numerical evaluation of these results when compared with the experimental results demonstrates superior accuracy with higher-order finite element mesh. The investigation carried out by higher-order element meshing approach is based on the subparametric transformation of parabolic arcs of triangular element curved at one side. Moreover, the high aspect ratio meshes obtained during discretization of airfoil design have been considered for the analysis. The investigation has yielded results that closely align with experimental data, demonstrating excellent performance. The current efficient analysis of pressure and flow transition is beneficial in interpreting aerodynamic performance and flow simulations for aerospace and computational fluid dynamics applications. [ABSTRACT FROM AUTHOR]

The paper discusses the possible determination of steam parameters in a new type of piston machine for steam compression to generate supercritical water parameters. It presents a calculation model that allows one to simulate the process of steam compression in a cylinder with volume regulated by the piston position. In each calculation step, the steam parameters were determined on the basis of fast adiabatic changes which were corrected by the effect of leakage and heat transfer occurrence. The seal of the reactor was assumed to be a compression ring. Depending on the pressure drop on the seal, subcritical and supercritical flow was taken into account. The leak was corrected by the coefficient of flow contraction. Heat transfer was determined by equations for the Nusselt number for water and steam from the homogenous area. The programmed model allows one to simulate changes in the thermodynamic parameters of steam during the process of steam compression with any calculation step. The results presented in this paper show that the application of one compression ring allows us to obtain supercritical steam parameters. Various degrees of sealing leak tightness and their impact on the changeability of steam parameters were analyzed. Heat transfer was shown to have an impact not only on changes in steam temperature, but also on pressure. This paper analyzes the impact of the temperature of the walls of the compression chamber on the value and direction of heat transfer. [ABSTRACT FROM AUTHOR]

In light of the current global climate changes, floods have emerged as a significant hydraulic and hydrological challenge on a global scale. The primary contributors to the expansion of impermeable areas and the intensification of flood flow are extensive urbanization, the proliferation of concrete edifices and the construction of asphalt thoroughfares. Anticipating the flow beforehand will be conducive to the successful execution of the task at hand. The objective is to reduce the likelihood of harm to individuals and damage to assets. By accurately determining the flow coefficient, which is a significant factor in flood flow, it is possible to mitigate existing issues to a significant degree. Numerous methodologies for modeling flow coefficients can be found in the extant literature. However, most of these methodologies rely on black-box techniques and are not easily generalizable. Hence, the present investigation has opted for a novel methodology; namely, the fuzzy SMRGT method that takes into account the physical characteristics of the phenomenon and is designed to assist individuals who encounter difficulties in selecting the appropriate quantity, structure and rationale of membership functions and fuzzy rules within a given fuzzy set. The data comprising annual precipitation, temperature and relative humidity measurements was acquired from the Regional Directorate of Meteorology. The model outcomes were juxtaposed with the actual observations. Statistical parameters, such as the coefficient of determination (R²), the root mean square error (RMSE), the Nash-Sutcliffe efficiency coefficient (NSE) and the mean absolute percentage error (MAPE), were used to evaluate the performance of the model. The statistical test results were: (RMSE: 0.096, NSE: 0.90, MAPE: 17.3, R²:0.96). The findings suggest that the SMRGT model is highly effective in accurately forecasting the flow coefficient and represents a robust approach for constructing membership functions and fuzzy rules. [ABSTRACT FROM AUTHOR]

Piano key overflows have a high discharge capacity. Proper design of these overflows requires sufficient accuracy in predicting the type of overflows. In this study, experiments were performed in a rectangular laboratory flume made of Plexiglas to investigate the effect of the relative length and width of the two-cycle piano switch overflow crest on the discharge coefficient. In present research, the flow intensity coefficient was investigated by installing a rectangular piano switch overflow with relative crest lengths of 0.8, 1, and 1.2 and relative crest widths of 0.2, 0.3, and 0.4 in 10 flow intensities in the channel. The results of this study showed that by increasing hydraulic load, the flow intensity coefficient first increases and then decreases. Also, by increasing the relative length of the crest by 50%, the current intensity coefficient increases by 43% in the overflow. Increasing the relative width of the overflow crest by 50% increases the current intensity coefficient by 25% in the overflows. Also, an equation was presented to determine the maximum relative scour depth, and the correlation coefficient of the results of this equation with the laboratory results is about 0.90. [ABSTRACT FROM AUTHOR]

While such traditional geophysical boundary layers have enjoyed over a decade of intense study, the inaccessibility of the deep ocean and the need for large spatial arrays to resolve scale dependent processes has limited our understanding of the ocean bottom boundary layer. Boundary layer processes play a crucial role in establishing the circulation patterns of the oceans and atmosphere, significantly affecting both regional and global climate, as well as the distributions of heat, nutrients, species, pollutants and more. Nagano et al. [[31]] advance the understand of the ocean bottom boundary layer through observations performed around Japan under a unique cooperative project among oceanographers and seismologists, which has unveiled the ocean variabilities near the bottom [[32], [34], [36]]. [Extracted from the article]

In this paper, we study the following quasilinear chemotaxis system  ut = Δu - χ∇ · (φ(u)∇v) - ξ∇ · (ψ(u)∇w) + f (u), x ∈ Ω, t > 0, 0 = Δv - v + vγ1 1, 0 = Δv1 - v1 + uγ2, x ∈ Ω, t > 0, 0 = Δw - w + wγ3 1, 0 = Δw1 - w1 + uγ4, x ∈ Ω, t > 0, in a smoothly bounded domain Ω ⊂ Rn(n ≥ 1) with homogeneous Neumann boundary conditions, where φ(ϱ) ≤ ϱ(ϱ+1)θ-1, ψ(ϱ) ≤ ϱ(ϱ+1)l-1 and f (ϱ) ≤ aϱ-bϱs for all ϱ ≥ 0, and the parameters satisfy a, b, χ, ξ, γ2, γ4 > 0, s > 1, γ1, γ3 ≥ 1 and θ, l ∈ R. It has been proven that if s ≥ max{γ1γ2 + θ, γ3γ4 + l}, then the system has a nonnegative classical solution that is globally bounded. The boundedness condition obtained in this paper relies only on the power exponents of the system, which is independent of the coefficients of the system and space dimension n. In this work, we generalize the results established by previous researchers. [ABSTRACT FROM AUTHOR]