Flow Velocity Distribution Research Articles

Liquid–Solid Coupled Internal Flow Field Analysis of Natural Gas Hydrate Spiral-Swirling Downhole In Situ Separator

This study aims to solve the problem of the recovery efficiency of natural gas hydrate being affected by a large amount of mud and sand in the solid fluidization mining of natural gas hydrate. Therefore, a new method for the separation of in situ sediment and natural gas hydrate in a spiral-swirling downhole is proposed, and the corresponding numerical simulation model is established to realize the analysis and verification of key flow field parameters such as flow velocity, pressure, sediment, and natural gas hydrate phase distribution. The results show that the flow velocity field of the mixed slurry presents an ‘M’-shaped symmetrical distribution, and the slurry near the wall of the separator can obtain a larger flow velocity, which is beneficial to the separation of mud–sand and natural gas hydrate. The static pressure field shows an axisymmetric distribution that decreases first and then increases, indicating that the pressure of the mixed slurry increases with the increase in the radial position, and the closer to the wall, the greater the static pressure of the mixed slurry. Near the wall of the separator, the volume fraction of the sediment phase reaches the maximum. In contrast, the volume fraction of the natural gas hydrate phase reaches the minimum, which confirms the separation effect of the sediment and the natural gas hydrate. The results show that the separation of sediments and natural gas hydrate can be realized, thereby improving the exploitation efficiency of natural gas hydrate. The designed spiral cyclone coupling separator provides a new solution to solving the problem of sand removal in natural gas hydrate exploitation.

Comparative studies of welded joints of rails after various hardening methods

The paper studies changes in temperature and pressure during hardening using the factory and upgraded sprayer of the UIN cooling system. The hardness distribution was studied for one- and two-sided cooling. The analysis of the obtained results shows that the greatest decrease in hardness is observed at a distance of 50 mm from the weld center. These points are the heat-affected zone from the action of the inductor of the induction unit. According to the regulatory documentation, a decrease in hardness of up to 15% is allowed during heat treatment of a welded joint compared to the hardness of the base metal. The results were obtained after upgrading the induction unit cooling sprayer in terms of expanding the hole zone and increasing the diameter of the holes in the lower shelf of the sprayer. The hardness measurement results indicated the shortcomings of induction heating during local heat treatment with a one-sided air distribution system on an induction unit of the UIN-001-100/RT-S(P) type. It was necessary to modify the cooling sprayer design to increase the intensity of the compressed air flow and to ensure uniform distribution of the air flow velocity onto the rail head. Also, to achieve an air flow rate of at least 200 m/s in the upper hardening unit, it is necessary to change the compressor unit control system. The sprayer modification allowed to increase the intensity of the hardening device operation in the central area of the rail head and the heat-affected zone from the inductors. The modification of the upper hardening unit ensures uniform distribution of the air on the rolling surface of the head during hardening and uniform distribution of hardness in the central area of the head, in the areas of the rail fillets, in the transition zones. This will eliminate the defect of chipping and crushing of the rail head metal during the operation of welded joints.

Velocity distribution of open channel flow within submerged rigid vegetation with non-uniform height

ABSTRACT The presence of vegetation in rivers causes significant changes in the hydraulic characteristics of the flow, and to perform correct management work, sufficient knowledge of these changes in the behavior and characteristics of the river must be obtained. Most of the researches on river vegetation assumed equal plant height, while this uniformity does not occur in natural circumstances. The present research investigates the vertical distribution of velocity in the presence of submerged rigid vegetation and uniform turbulent flow with a random height distribution. The results reveal that cylinder height distribution has a significant influence on longitudinal profile characteristics such as curvature magnitude. In the present study, the flow is categorized into three layers: the upper layer (non-vegetated layer), the upper vegetation layer, and the lower vegetation layer. Using the wide range of laboratory data obtained in the present research, new equations have been developed in order to determine velocity distributions in these three layers. The velocity profiles incorporate two inflection points whose locations are affected by the vegetation density and submergence rate.

Numerical and field investigation to improve an existing distributed-sediment-excluder sand trap performance

ABSTRACT Sand traps are essential for managing sedimentation in irrigation systems, ensuring the efficiency and longevity of water infrastructure. This study addresses the underperformance of the Lower Usuthu Smallholder Irrigation Project (LUSIP) sand trap in the Usuthu River basin, eSwatini, where sediment build-up disrupts its operational efficiency. Field investigations and advanced numerical modeling using ANSYS Fluent, the study evaluates the trapping and flushing efficiency of the sand trap. A fully coupled 3D numerical model simulates hydrodynamics and sediment transport, focusing on flow velocity and suspended sediment concentration distributions under both maximum design discharge and low-flow conditions. Field investigations revealed a trapping efficiency of 27% and a flushing efficiency of 36% during low-flow conditions, primarily due to turbulence and design limitations. Numerical simulations identified critical sediment deposition patterns and flow dynamics, leading to design recommendations. With the proposed modifications, the sand trap's trapping efficiency is projected to increase to 85%, while flushing efficiency is expected to reach 80% under low-flow conditions. This study introduces innovative modeling approaches to assess three-dimensional flow dynamics in distributed-sediment-excluder systems, offering actionable insights for optimizing sediment management in irrigation infrastructure. These findings contribute to sustainable agricultural development and water resource management, addressing challenges in semi-arid regions.

Exploring the effects of nanoparticle radius and inter-particle spacing on mixed convective dusty nanofluid flow over an extending heated surface: A numerical analysis

This work has investigated a water-based dusty nanofluid flow past an extending surface that contains copper nanoparticles. The influences of the magnetic field, gravitational field, nanoparticle radius, interparticle spacing, thermal radiation, and heat source are also taken into account in this research. PDEs are used for presenting a mathematical model, which similarity variables are then used to convert into ODEs. Using the shooting approach, a numerical solution is determined. To assure the correctness of the numerical solution while keeping computational performance, we have employed both absolute tolerance (AbsTol = 10−5) and relative tolerance (RelTol = 10−5) for the derived results. Based on the acquired data, it is concluded that a larger magnetic factor increases drag force whereas a higher mixed convection factor decreases it. The heat transfer rate is increased by the larger thermal radiation factor and thermal Biot number. The axial velocity profiles are enhanced by the larger mixed convection component. Conversely, transverse velocity profiles are reduced close to the sheet’s surface by a larger mixed convection factor, while an opposite tendency is seen far from the sheet’s surface. The axial and transverse velocity distributions of both phases are decreased by the larger inter-particle spacing. The axial and transfer velocity profiles of both phases are boosted by the larger nanoparticle radius. The temperature profiles of both phases are heightened by the greater thermal Biot number and heat source factor. Overall, the analysis highlights that the embedded parameters significantly influence the velocity and thermal distributions of the nanofluid flow with a more pronounced impact on the nanofluid flow phase compared to the dusty nanofluid flow phase. These insights provide valuable guidance for the optimization of flow and thermal properties in engineering systems involving dusty nanofluids.

An analytical study for predicting incipient motion velocity of sediments under ice cover

This study investigates the critical impact of incipient sediment motion on sediment transport estimation and riverbed evolution prediction. In this research, we examine the effects of ice cover on the vertical distribution of flow velocity, establishing a mathematical relationship between the vertical average flow velocities in open channel and ice-covered flows. This leads to the derivation of a formula for incipient motion velocity under ice cover. Additionally, the study analyzes the riverbed evolution process under ice jam conditions. The proposed formula is applicable to both open channel and ice-covered flows, effectively capturing the characteristics of incipient sediment motion for non-cohesive and cohesive sediments. The calculated incipient motion velocities closely align with the empirical data from existing literature. The study reveals that the roughness of ice cover significantly influences the incipient motion velocity of sediment, with higher ratios of ice cover roughness to riverbed roughness promoting sediment initiation under more favorable hydraulic conditions. Furthermore, the riverbed beneath ice jams experiences significant scouring. Field observations indicate that when ice jams form in localized sections of the river, the displacement of the main flow can substantially increase flow velocity in areas away from the ice jam, leading to scouring in non-ice-jammed areas and sedimentation in ice-jammed areas. The uneven distribution of ice jam is likely a critical factor contributing to discrepancies between theoretical predictions and observed outcomes. The complexity and limited data associated with the initiation of cohesive sediments pose challenges in validating the proposed formula for these sediment types.

Influence of Processing Parameters on Flow Behaviour of Ultra-Large-Section Beam Blank Continuous Casting Mould.

The complex cross-sectional shape of oversized beam blanks and the size effect of ultra-large-section beam blanks create severe issues related to the surface and internal quality of the castings. To ensure quality and control in the production of ultra-large-section beam blanks, a numerical and physical model of molten steel flow in the three-port submerged entrance nozzle (SEN) mould, with section dimensions of 1300 × 510 × 140 mm, was established. This model was created using numerical simulations and NSGA-II genetic algorithm optimisation, and the impact of the casting speed and SEN immersion depth on the mould's flow behaviour was investigated. The results showed that a deeper SEN immersion depth resulted in, a greater impact depth of the molten steel, and the surface flow velocity decreased. Both the impact depth and the surface flow velocity of the molten steel increased with increasing casting speed. The physical simulation and numerical simulation of the molten steel flow form and flow velocity distribution in the mould were in good agreement with each other, thus verifying the accuracy of the numerical simulation. The process parameters derived from this study were all within an appropriate range, which can help to improve the quality of continuously cast beam blanks. This also provides guidance for selecting optimal parameters for actual continuous casting production processes.

Improved particle tracking velocimetry based on level set segmentation for measuring the velocity field of granular flow

Abstract Using traditional particle tracking velocimetry based on optical flow for measuring areas with large velocity gradient changes may cause oversmoothing, resulting in significant measurement errors. To address this problem, the traditional particle tracking velocimetry method based on an optical flow was improved. The level set segmentation algorithm was used to obtain the boundary contour of the region with large velocity gradient changes, and the non-uniform flow field was divided into regions according to the boundary contour to obtain sub-regions with uniform velocity distribution. The particle tracking velocimetry method based on optical flow was used to measure the granular flow velocity in each sub-region, thus avoiding the problem of granular flow distribution. The simulation results show that the measurement accuracy of this method is approximately 10% higher than that of traditional methods. The method was applied to a velocity measurement experiment on dense granular flow in silos, and the velocity distribution of the granular flow was obtained, verifying the practicality of the method in granular flow fields.

Simulation of dynamic response changes in curved river flow under landslide-induced surge wave influence

This article uses a three-dimensional loose rock landslide surge model test in shallow water areas under dynamic water conditions to study the dynamic response characteristics of river flow. Based on the observation of the changes in the flow field and morphology of the river surface before and after the landslide body enters the water using a large-scale surface flow field measurement system, the changes in the river flow conditions under the influence of landslide surges are divided into four main stages: normal water flow state, landslide inflow disturbance state, wave current coupling motion state, and accumulation body ejection state. According to the acoustic Doppler velocimeter flowmeter arranged at the intersection of the initial surge waveform centerline and the mainstream flow direction, the three-dimensional velocity time-domain process near the water surface is measured and analyzed. Based on different cross sections and measuring points in the landslide area and its upstream and downstream, a non-steady flow propeller flowmeter and an ultrasonic wave/water level acquisition analyzer were arranged to measure and reveal the longitudinal and transverse flow velocity distribution and water surface line variation of the river under the influence of landslide surge.

Experimental Investigation of Hydraulic Characteristics for Open Channel Gates

As irrigation districts rapidly advance in terms of informatization, research on intelligent water quantity control technologies for open channels has gained increasing importance. This study aims to investigate the flow capacity and hydraulic characteristics of gates in open channels, focusing on the flow measurement and the hydraulic behavior around water-measuring structures. Although automated control in irrigation systems has achieved significant development, research on the flow characteristics near gates remains limited. To address this gap, an integrated approach combining indoor physical model experiments with theoretical analysis was used. This study explored the water surface profile, cross-sectional flow velocity distribution, vertical velocity distribution, and turbulent kinetic energy under various gate opening conditions and flow rates. The findings reveal that the water surface exhibits a sharp rise upstream of the gate, followed by a steep decline and stabilization downstream, influenced by the gate’s water-blocking effect. The flow velocities near the gate opening differ significantly in direction and magnitude from those in other cross-sections, affecting both longitudinal and vertical velocities. The turbulent kinetic energy is concentrated near the gate opening, and the turbulent kinetic energy is primarily concentrated near the sidewalls and the channel bottom; the gate’s opening size plays a crucial role in its diffusion and distribution. Linear regression analysis was utilized to fit the gate flow coefficient formula, and a comparative analysis of the measurement accuracy was conducted. The relative error between the calculated flow values and the actual measured values is within ±5%, which meets the precision requirements specified in the water measurement standards for irrigation canal systems in the irrigation district. This study pioneers an integrated approach for investigating the hydraulic characteristics of gates in open channels, merging physical model experiments with theoretical analysis. It provides novel insights into how gate openings affect water surface profiles, flow velocity distributions, and turbulent kinetic energy. This research also underscores the role of gate discharge in turbulent kinetic energy distribution, offering technical insights to enhance flow measurement accuracy and prevent sediment deposition, thereby optimizing gate applications for efficient water management. Overall, this study significantly advances the understanding of open channel flow dynamics and holds substantial significance for the refinement of water quantity control techniques in irrigation districts.

Scale characteristics and growth process of shallow water delta under different lake levels— based on Delft3D numerical simulation research

Modern bays and lakes typically develop shallow deltas dominated by rivers, with lake levels playing a significant role in their formation. However, the precise effects of lake level height on the scale and growth dynamics of these deltas remain unclear. To address this, this study employs the sedimentary numerical simulation software Delft3D to model delta development under high, medium, and low lake levels. By analyzing flow velocity distribution, sediment accumulation, and sediment thickness, the study quantitatively assesses the impact of varying lake levels on shallow deltas. The results indicate that: (1) the areal extent of the delta is inversely related to the lake level, whereas sediment thickness is directly proportional to it; (2) within the same simulation period, higher lake levels tend to produce fewer breach distributary channels, while lower levels are more conducive to forming numerous breach distributary channels; however, the impact of lake level on active distributary channels is minimal; (3) deltas consist of multiple complexes. Under high lake levels, a single complex typically exhibits a bird-foot shape, characterized by active distributary channels and mouth bars, with sediment thickness decreasing from the source. In contrast, under low lake levels, a single complex tends to have a flower shape, with active distributary channels, mouth bars, and multiple breach distributary channels, resulting in a more evenly distributed sediment thickness. This research result can provide new ideas for the comparative evolution of deltas under different lake level water levels.

A Study on the Flow Measurement Performance of the Plate Flowmeter and Its Effect on Channel Flow Velocity Distribution

The plate flowmeter offers a novel method for water flow measurement in small channels. Characterized by its simple construction, absence of siltation, and consistent relationship between the deflection angle and flow rate, this device possesses significant potential. Our study, employing rigorous experimental techniques, validated that the gate-hole outflow calculation model is effectively applicable to this plate flowmeter. Additionally, our research investigated the device’s impact on flow velocity distribution. Our findings reveal that the plate flowmeter can be effectively combined with the sluice gate outflow model. It has been verified that the maximum relative error is 14.57%, the minimum relative error is 0.35%, and most relative errors are below 10%. Both water level and flow rate contribute to the flat plate device’s relative head loss, with water level exerting a more significant effect. At various points along the channel, the plate flowmeter affects flow velocity distribution differently. Upstream, the device minimally impacts vertical flow velocity distribution, resulting in steady velocity changes. Conversely, downstream, the flat plate flow meter significantly alters flow velocity distribution, prompting redistribution that persists until 1.26 m downstream, where device influence ceases. These insights offer a solid theoretical foundation for enhancing the structural design of the plate flowmeter, thus improving its overall performance and efficacy.

Study on simulated airflow dynamics of children with obstructive sleep apnea treated by different surgical methods

Objective:To analyze the effects of adenoidectomy, tonsillectomy and tonsillectomy combined with adenoidectomy on obstructive sleep apnea children by computational fluid dynamics numerical simulation. Methods:A case of typical tonsil with adenoid hypertrophy was selected. Mimics 21.0 software was used to establish the original preoperative model, adenoidectomy, tonsillectomy and virtual surgical models of tonsillectomy combined adenoidectomy, and the computational fluid dynamics model of the upper airway was established by ANSYS 2019 R1 software, and then the pressure and velocity of the internal flow field of the CFD model were numerically simulated. Seven planes perpendicular to the flow trace were selected as the observation planes, including the cross section of the sinusostoma complex, the anterior end of the adenoid body, the narrowest cross section of the nasopharyngeal cavity, the pharyngostoma tube, the narrowest cross section of the oropharyngeal cavity, the lower pole of the tonsil and the glottis section. The comparison indexes included pressure, flow velocity and flow distribution. Results:Compared with the original model before operation, after the adenoids were removed only, the pressure drop between the section of the ostiomeatal complex and the section of the eustachian tube decreased, the high velocity peak at the anterior end of the adenoids disappeared, and the flow trace through the middle nasal canal increased. When only bilateral tonsils were removed, the pressure drop between the eustachian tube and the glottis slowed down and the flow velocity between the eustachian tube and the glottis slowed down. Combined tonsillar-adenoidectomy resulted in the most uniform pressure distribution, the most gentle pressure change and flow rate in the upper airway, and the most ignificant increase in airflow trace through the middle nasal canal among the three operations. Conclusion:Adenoidectomy, tonsillectomy and combined tonsillar adenoidectomy can make the airflow velocity and pressure of upper respiratory tract uniform to different degrees, but there are obvious differences in the specific anatomical location and degree. The application of CFD can intuitively predict the improvement of upper airway flow field in OSA children by different surgical methods, which helps clinicians to make surgical decision.

Dimensionality reduction of high-solid anaerobic digestion flow pattern: Flow velocity distribution model and control strategy

Dimensionality reduction of high-solid anaerobic digestion flow pattern: Flow velocity distribution model and control strategy

A simplified method for estimating the alpha coefficient in surface velocity based river discharge measurements

Remote sensing techniques for river monitoring facilitate faster measurement campaigns compared to traditional methods, reduce risks to personnel and instruments, and allow measurements under critical flow conditions. An alpha coefficient (α) is commonly employed to convert surface velocities, obtained by contactless techniques, into depth-averaged velocities, which are used for the application of the velocity-area method for assessing discharge. Some optical-based software programs use a constant α value, based on a theoretical “standard”. However, analyses of empirical vertical velocity profiles in real cases reveal that α can significantly deviate from this standard due to various factors (roughness, turbulence, etc.).This study analyzes several ADCP (Acoustic Doppler Current Profiler)-based measurements in Sicily, Italy, to explore factors influencing flow velocity distribution and potential errors from using the standard α for discharge estimation via surface velocity-based methods. The results confirmed substantial variability in α, which is functionally related to some geometric factors characterizing the cross-section shape and the specific vertical where the velocity profile is computed. The generated dataset of empirical α values is also used to implement an Artificial Neural Network (ANN), offering a straightforward tool suitable for non-contact techniques. The ANN predicts α at any vertical of a measurement transect as a function of variables however necessary for discharge assessment by non-intrusive methods, leading to depth-averaged velocity estimates from surface velocities that are more accurate than those derived from conventional approaches, as demonstrated by four test cases.

The Influence of Non-Pressure Pipes Filled to Different Degrees on the Hydraulic Characteristics of Channel–Pipe Combined Irrigation Systems

Modern irrigation areas often use a combination of channels and pipes for irrigation. Due to changes in terrain, inflow, and pipe diameter, pipelines are often prone to experiencing a state of no pressure. This lack of pressure affects not only the velocity distribution and water surface profile of the main channel but also the velocity distribution and flow distribution of the pipeline. Therefore, in this study, we employed a combination of physical model experiments and theoretical analysis to study the influence of non-pressure pipelines on the hydraulic characteristics of channel–pipe combined irrigation systems filled to different degrees. Through this, the variation laws of the flow velocity distribution, turbulence intensity, water surface, diversion width, and diversion ratio under different filling degrees were obtained. The non-pressure pipeline flow velocity expression was obtained through dimensional analysis, and the calculation formula for the non-pressure pipeline flow velocity coefficient was fitted using linear regression analysis. The relative error between the calculated value and the measured value did not exceed 8.81%. The research results presented in this article can provide technical support for the design and maintenance of channel–pipe combined irrigation systems.

Mechanism of shear-enhanced rotating-disk microfiltration for separation of microbe/protein bio-suspension

Shear-enhanced dynamic filtration is a promising approach for separating fermented biological products. In this study, we aimed to investigate the separation of bovine serum albumin (BSA) and polymethyl methacrylate (PMMA) particles in a binary suspension using rotating-disk microfiltration. Type-R and Type-RB rotating-disk configurations were designed and compared using experimental data and simulated results. The effects of operating conditions, including rotational speed and filtration pressure, on filtration flux, resistance, and protein rejection, were analyzed. Because the filter membrane rejected all the PMMA particles, the primary source of filtration resistance in the PMMA/BSA suspension was the fouling cake. Although BSA rejection increased with higher filtration pressure, it decreased as the rotational speed increased. Computational fluid dynamics simulations were used to model the flow velocity and shear stress distributions within the rotating-disk dynamic microfiltration system. The results showed that Type-RB achieved a 55 % increase in flux compared to Type-R, owing to a significant reduction in cake resistance by approximately 46 %. A proportional relationship between the mean cake mass and the ratio of qs/τw under varying operating conditions was established using a force balance model. These findings suggest that elevated shear stress significantly enhances filtration performance, with Type-RB demonstrating superior effectiveness for bio-suspension separation.

Parameter Optimization of Spiral Step Cleaning Device for Ratooning Rice Based on Computational Fluid Dynamics-Discrete Element Method Coupling

Ratooning rice plants have a high moisture content and strong adhesion during harvesting. Traditional cleaning devices are prone to clogging when processing ratooning rice, resulting in a series of problems such as high grain loss rate and high grain impurity rate. In response to the above issues, this article adopts the CFD-DEM coupling method to design a spiral step cleaning device. A detailed analysis was conducted on the influence of the cone angle and thickness of the spiral-stepped skeletons on the flow state, and flow velocity and pressure distribution cloud maps were obtained under different structural parameters. The vortex morphology under different thicknesses of the spiral-stepped skeletons was compared, and the structural parameters of the device were determined. The motion trajectory and distribution of impurity particles under different inlet flow velocities were analyzed using data superposition, and the appropriate inlet flow velocity range was determined. A test bench was built, and a three-factor quadratic regression orthogonal rotation combination experiment was conducted with fan speed, feeding rate, and device inclination angle as experimental factors. The results of the bench test show that the performance index reaches its optimum when the device inclination angle, fan speed, and feeding rate are 2.47°, 2906 r/min, and 4.0 kg/s, respectively. At this time, the grain impurity rate, grain loss rate, and sieve clogging rate are 2.21%, 2.15%, and 3.5%, respectively. Compared to those of traditional cleaning equipment, these value are reduced by 44.5%, 39.6%, and 83.9%, respectively. This study can provide ideas for the design of ratooning rice cleaning devices.

Initial Experimental Investigation of Hydraulic Characteristics at Right-Angle Diversion in a Combined Canal and Pipe Water Conveyance System

To enhance the efficiency of irrigation water utilisation, China is progressively converting irrigation ditches into pipelines. The water distribution outlets in irrigation zones are predominantly right-angled, and there are typically occurrences of erosion, sedimentation, and structural deterioration in the surrounding areas. This article employs a synthesis of indoor physical model experiments and theoretical analysis to examine the distribution of channel flow velocity and variations in water surface profile, pipeline flow rate, diversion ratio, circulation intensity, and turbulence energy across different relative water depths. The experimental results indicate that the water surface adjacent to the main canal wall demonstrates a pattern of initial decline, followed by an increase and subsequently another decline; furthermore, as the water level in the main channel rises, the magnitude of this fluctuation progressively diminishes. In some sections of the canal, the water surface elevation progressively increases, albeit with minimal amplitude. With a constant relative water depth, an increase in main channel flow results in a corresponding increase in pipeline flow; however, the diversion ratio is inversely related to the main channel flow. Conversely, when the main channel flow rate is constant, the diversion ratio increases as relative water depth rises. The vertical flow velocity near the water diversion outlet has a negative value, signifying the existence of a backflow zone, while the horizontal flow velocity varies considerably, facilitating the formation of circulation and resulting in localised deposition and erosion. The water flow near the pipe inlet downstream of the lower lip of 0.5 times the pipe diameter is impacted by the return zone, which has a higher turbulence energy and circulation strength and is more susceptible to siltation. The turbulence energy of the water flow is higher in the range of 0.5 times the pipe diameter upstream and downstream of the pipe inlet. This research is highly significant in facilitating the conversion of irrigation channels into pipelines.

An Experimental Study of Flow and Turbulence Properties near the Rising Sector Gate Mouth Considering the Gate Opening with a PIV Measuring System

Hydraulic structures, such as movable weir gates, are widely installed in rivers and streams for various purposes. Among these is the rising sector gate, which is the focus of this study. This research investigated how different gate openings affect flow velocity and turbulence distributions at the gate mouth. A hydraulic analysis of flow and turbulence characteristics near the mouth of a rising sector gate model was conducted through laboratory experiments with various flow conditions and gate openings utilizing a Particle Image Velocimetry (PIV) system. Experimental tests were carried out with two gate-opening angles (30 and 45 degrees). The PIV measurements revealed significant variations in flow velocity and turbulence properties in response to the gate openings and flow conditions. Notably, in the vicinity of the gate mouth, where the flow regime changes rapidly between the upstream and downstream regions, the turbulence properties in the upstream part of the gate mouth were more than twice those in the downstream part. Additionally, the streamwise distribution of depth-averaged relative turbulence intensity was analyzed. The results showed that the depth-averaged relative turbulence intensity decreased by nearly half as the gate opening increased from 30 to 45 degrees, with the lowest values observed at the gate mouth, followed by an increase downstream. A functional relationship between the maximum flow velocity at the gate mouth during underflow operation and the Froude number was established to guide practical gate operation in the field.