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The transport phenomenon in the presence of magnetic field has diverse application in living structures, biotechnology and chemical and environmental engineering. Biomedical applications include the examples of computational biology, replacement of tissue, drug delivery, advance medical imaging, repairing of bones, complex liver and heart surgeries and kidney transplant. Motivated by the applications of magnetic in human physiology, peristaltic transport of Carreau-hybrid nanomaterial through a curved channel is studied. The hybrid nanofluid is supported with silver (Ag) and copper oxide (CuO) nanoparticles subject to ethylene glycol (EG)-based liquid. The complex wavy nature of physiological duct inspired to model the problem in complex wavy channel. The basic governing laws are utilized for mathematical modeling and dimensionless variables are used for the dimensionless formulation. The simplified pattern of governing problem has been revealed to the assumptions of long wavelength as well as creeping flow constricts. The computations are obtained by implanting the Newton–Dirichlet Solve (ND) algorithm. Comparative thermal observations are predicted for nanofluid (Ag/EG) and hybrid nanofluid (Ag–CuO/EG). The different flow and heat transfer features are plotted against the several involved parameters are presented graphically. [ABSTRACT FROM AUTHOR]

Few studies have focused on abutments located on curved channels; previous studies have typically focused on straight channels. The present study experimentally examined the local scour that occurs around abutments of different lengths placed on inner and outer banks along a curved channel under clear-water scour flow conditions. The local scour around an abutment in a curved channel is a function of the upstream Froude number, flow intensity, the angle of the bend curvature and the ratios of abutment length to flow depth, abutment length to abutment width and abutment length to channel width. The maximum scour depth around the abutments placed on the outer bank was 1.45 times the scour depth on the inner bank. An empirical equation was developed containing all the dimensional parameters for equilibrium scour depth. The average percentage error of the proposed equation was 2%. [ABSTRACT FROM AUTHOR]

In order to study the supercritical flow in a curved channel of a rectangular cross section, the classical shallow water equations in a cylindrical coordinate system based on the mass and momentum laws that take into account the friction and bottom slope are used. The obtained mathematical model forms nonlinear partial differential equations of first-order. For simplification, a linearization of the partial differential equations (PDEs) set is performed using small perturbation approach valid for weak bends (axial curvature radius extremely larger than the channel width). The governing equations with well-posed initial and boundary conditions were solved for a rectangular bend channel flow by applying the method of characteristics that is capable of transforming the hyperbolic partial differential equations to a system of ordinary differential equations (ODEs). The proposed model is tested and validated by comparing the results with broad available experimental data reported in the literature, and particular attention was paid to the wave maximum and its location. Comparisons indicate a reasonable agreement between the results obtained for the maximum flow depth along the outer channel wall. However, the model prediction is only reliable for a small relative curvature. Despite the model limitations, the results show the reliability and accuracy of the proposed approach for practical design purposes. [ABSTRACT FROM AUTHOR]

High gravity (high-g) combustion can significantly increase flame propagation speed, thereby potentially shortening the axial length of aero-engines and increasing their thrust-to-weight ratio. In this study, we utilized the large eddy simulation model to investigate the combustion characteristics and flame morphology evolution of premixed propane–air flames in a channel with a backward-facing step. The study reveals that both the increase in centrifugal force and flow velocity can enhance pressure fluctuations during combustion and increase the turbulence intensity. The presence of centrifugal force promotes the occurrence of Rayleigh–Taylor instability (RTI) between hot and cold fluids. The combined effects of RTI and Kelvin–Helmholtz instability (KHI) enhance the disturbance between hot and cold fluids, shorten the fuel combustion time, and intensify the dissipation of large-scale vortices. The increase in fluid flow velocity can raise the flame front's hydrodynamic stretch rate, thereby enhancing the turbulence level during combustion to a certain extent and increasing the fuel consumption rate. When a strong centrifugal force is applied, the global flame propagation speed can be more than doubled. Within a certain range, the increase in high-g field strength can enhance the intensity of RTI and accelerate the transition of RTI to the nonlinear stage. [ABSTRACT FROM AUTHOR]

A curved channel is a common flow form in nature, often hosting aquatic vegetation along rivers. The stem thickness of this vegetation affects its resistance to flow and subsequently influences flow characteristics. To explore the impact of stem thickness on river flow in curved channels, we developed a Reynolds stress model based on real river flow conditions and vegetation data. The flow characteristics were analyzed in terms of flow velocity, Reynolds stress and turbulence intensity by varying the stem thickness of the vegetation in the vegetated area. The results of the study reveal that: (1) Water velocity in the vegetated area is significantly reduced compared to the non-vegetated area, with a greater reduction observed for thicker stems. Increasing the vegetation diameter by 3 mm resulted in a velocity decrease of 2.31–26.55%. (2) Thicker vegetation stems lead to more intense energy exchange in water flow. A 3 mm increase in vegetation diameter increased Reynolds stress by 91.81–139.70%. (3) Turbulent kinetic energy in the vegetated area is significantly higher than in the non-vegetated area, with greater turbulence intensity observed for thicker vegetation stems. Increasing the vegetation diameter by 3 mm resulted in a turbulent kinetic energy increase of 115.19–218.55%. HIGHLIGHTS Less research has been done on the effect of vegetation stem thickness on water flow in curved channels.; The feasibility of studying the flow characteristics of curved river channels through simulation is verified.; Analysis of sedimentation by comparing concave and convex shores.; The results can guide the construction of river channels and the design of aquatic systems.; It can provide relevant data for the subsequent research on the influence of vegetation stem coarseness on water flow characteristics.;

Cilia flow plays a crucial role in biological systems such as the movement of mucus in the respiratory tract, circulation of cerebrospinal fluid in the brain, and propulsion of sperm cells. Understanding the cilia flow of viscous fluids is essential for elucidating the biomechanics of these processes and their implications for health and disease. Motivated by such numerous biomedical applications, this article aims to exhibit the impact of variable thermal conductivity on the mixed convective cilia beating transport of viscous fluid in a curved channel in the presence of radial magnetic field. The energy equation is also modulated with heat source/sink and viscous dissipation impacts. The constitutive equations are simplified by the hypothesis of lubrication approximation theory and then solved numerically using the implicit finite difference method (FDM). The numerical results concerning the impacts of various physical parameters on the velocity, temperature, pumping phenomena, and streamlines are graphed and explained. The obtained results indicate that as the Hartman number upsurges, fluid velocity reduces, and the Brickman number shows stronger viscous dissipation effects, leading to an increase in the fluid temperature.

In the aftermath of the worldwide severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, the disposal of plastic and nonwoven fabric materials originating from personal protective equipment (PPE) into freshwater bodies like lakes and rivers has significantly increased. Surface plastic transport and accumulation have become a relevant source of pollution that adversely affects the quality of water and fluvial ecosystems. Although attempts have been made in the past to study the flow characteristics of plastic at the river surface, an in-depth study of structural configurations that can act as potential plastic traps, facilitating reduction of pollution due to plastic transport, is necessary. This paper investigated the hydrodynamics of surface plastic transport in the presence of several control structures. In addition, useful empirical equations were derived to predict the kinematic and trapping efficiency of the mentioned structures, valid for both straight and curved channels under a variety of hydraulic and geometric conditions. It was found that the Froude number and position of the structure play a dominant role in influencing surface plastic transport mechanism and the overall efficiency of structures in limiting plastic transported downstream. [ABSTRACT FROM AUTHOR]

Due to natural and external influences in curved channels, ships frequently require adjustments in course and speed, posing challenges for existing control methods. Particularly lacking are speed control methods suitable for curved channel navigation. This study initially developed a three-degree-of-freedom MMG model incorporating external interference. It introduced an OP-PID heading controller merging optimal control strategies with traditional PID, adaptable to both external conditions and ship speed, validated through heading control simulations. The study analysed the ship's speed change process, deriving a mathematical expression for advance distance, and proposed a dichotomy-based speed control method to determine speed change points, addressing differential equations with unknown integrands. To mitigate uncertainty errors like parameter inaccuracies in ship maneuvering models and dynamic environmental disturbances, the study proposed a comprehensive control approach. This approach integrates model predictive control, feedback compensation, segment identification, and an enhanced line-of-sight (LOS) guidance method alongside the OP-PID course controller and dichotomy-based speed control. Simulation experiments in the Dongboliao Channel compared the proposed and existing methods. Results demonstrate the proposed method's capability to handle frequent course and speed adjustments effectively, even under model errors and external interference, showcasing superior track deviation and course control accuracy over existing methods. [ABSTRACT FROM AUTHOR]

Cilia flow plays a crucial role in biological systems such as the movement of mucus in the respiratory tract, circulation of cerebrospinal fluid in the brain, and propulsion of sperm cells. Understanding the cilia flow of viscous fluids is essential for elucidating the biomechanics of these processes and their implications for health and disease. Motivated by such numerous biomedical applications, this article aims to exhibit the impact of variable thermal conductivity on the mixed convective cilia beating transport of viscous fluid in a curved channel in the presence of radial magnetic field. The energy equation is also modulated with heat source/sink and viscous dissipation impacts. The constitutive equations are simplified by the hypothesis of lubrication approximation theory and then solved numerically using the implicit finite difference method (FDM). The numerical results concerning the impacts of various physical parameters on the velocity, temperature, pumping phenomena, and streamlines are graphed and explained. The obtained results indicate that as the Hartman number upsurges, fluid velocity reduces, and the Brickman number shows stronger viscous dissipation effects, leading to an increase in the fluid temperature. [ABSTRACT FROM AUTHOR]

This study developed a novel dielectric wetting microfluidic operation platform combining parallel-plate and coplanar-plate regions with a curved surface structure as the connection structure. With the new electrowetting on dielectric (EWOD) platform, "droplet pull-out" has been successfully achieved and viewed as an essential new operation for microfluidics with the dielectric wetting technique. The EWOD system is divided into a PDMS substrate top plate and an indium tin oxide (ITO) glass substrate as a bottom layer on this chip. In the parallel-plate region, the droplets can be generated and transported through the square parallel electrodes; in the single-plate area, the droplets can be pulled out from the parallel structure, transported and mixed through the common grounded coplanar electrodes. In dielectric wetting performance testing, coplanar electrodes can apply a maximum driving force of 31.22 µN to DI water and 13.38 µN to propylene carbonate (PC). This driving force is sufficient to detach the sample from the top cover and pull the sub-droplet from the parallel plate structure for DI water, PC and polyethylene glycol diacrylate (PEGDA) buffer. The novel EWOD system also possesses the advantage of precise volume control for liquid samples; the volume error of the generated droplet can be controlled within 0.1% to 2%. [ABSTRACT FROM AUTHOR]

Abstract Supercritical flows in channel bends, e.g., in steep streams, chute spillways, and flood and sediment bypass tunnels (SBTs), experience cross-waves, which undulate the free surface. The designs of these hydraulic structures and flood protection retaining structures in streams necessitate computing the locations and water depths of the wave extrema. This study numerically and experimentally investigates the water surface profiles along the sidewalls, the wave extrema flow depths, and their angular locations in a narrow channel bend model of the Solis SBT in Switzerland. The 0.2 m wide and 16.75 m long channel has a bend of 6.59 m radius and 46.5° angle of deviation. The tested flow conditions produced Froude numbers ≈ 2 and aspect ratios ranging from 1.14 to 1.83. Two-phase flow simulations were performed in OpenFOAM using the RNG k–ε turbulence closure model and the volume-of-fluid method. The simulated angular locations of the first wave extrema and the corresponding flow depths deviate marginally, within ± 6.3% and ± 2.1%, respectively, from the experimental observations, which signifies good predictions using the numerical model. Larger deviations, especially for the angular locations of the wave extrema, are observed for the existing analytical and empirical approaches. Therefore, the presented numerical approach is a suitable tool in designing the height of the hydraulic structures with bends and conveying supercritical flows. In the future, the model’s application shall be extended to the design of the height and location of retaining walls, embankments, and levees in steep natural streams with bends.

The present study analyzed the curved channel with the flexible bed for its morphology and structural turbulent anisotropy. The result of the bed morphology shows that erosion on the outer bend of the channel was prominent, and sediment deposition was pronounced in the inner bed of the channel. Erosion and sediment deposition rates increase with the flow rate and time. The analysis presents an anisotropy invariant (Lumley triangle) for flow turbulence at different channel sections. At the apex of the curved channel, a pancaked structure with a higher magnitude confirms the presence of helical flow in the apex region. The presence of a cigar-shaped structure with a high magnitude on the right side of the bend compared to the left side may be attributed to higher turbulence on the right side (outer bend), which may result in erosion at the outer bend and lesser turbulence on the left side (inner bank) may result in sediment deposition. HIGHLIGHTS Experiments on the curved channel.; Bed morphology has been studied.; Turbulent anisotropy has been analyzed.; A pancaked structure was observed at the apex region.; Lesser turbulence on the inner bank.;

Supercritical flows in channel bends, e.g., in steep streams, chute spillways, and flood and sediment bypass tunnels (SBTs), experience cross-waves, which undulate the free surface. The designs of these hydraulic structures and flood protection retaining structures in streams necessitate computing the locations and water depths of the wave extrema. This study numerically and experimentally investigates the water surface profiles along the sidewalls, the wave extrema flow depths, and their angular locations in a narrow channel bend model of the Solis SBT in Switzerland. The 0.2 m wide and 16.75 m long channel has a bend of 6.59 m radius and 46.5° angle of deviation. The tested flow conditions produced Froude numbers ≈ 2 and aspect ratios ranging from 1.14 to 1.83. Two-phase flow simulations were performed in OpenFOAM using the RNG k–ε turbulence closure model and the volume-of-fluid method. The simulated angular locations of the first wave extrema and the corresponding flow depths deviate marginally, within ± 6.3% and ± 2.1%, respectively, from the experimental observations, which signifies good predictions using the numerical model. Larger deviations, especially for the angular locations of the wave extrema, are observed for the existing analytical and empirical approaches. Therefore, the presented numerical approach is a suitable tool in designing the height of the hydraulic structures with bends and conveying supercritical flows. In the future, the model’s application shall be extended to the design of the height and location of retaining walls, embankments, and levees in steep natural streams with bends. [ABSTRACT FROM AUTHOR]

Gravity currents modify their flow characteristics in the presence of an obstacle. Also, the flow path to the dam reservoirs is not always direct. Since no studies have addressed the feedback between the hydrodynamics of a gravity current in a curved channel and the location effects of the obstacle, in this research, a Lock-exchange density current flows in a 120 ∘ bending channel. The numerical simulation has been performed using OpenFOAM software. The models include no-obstacle curved channel and a curved channel with an obstacle in different positions concerning the increased radius of the curved channel. Results indicated that the obstacle directed the concentration towards the banks, with its maximum value tending from the outer to the inner bank, especially in the tail. The tail longitudinal velocity maximized near the channel bed in areas far from the obstacle, and in the outer bank in areas near it. The secondary flow reduces its lowest and most different pattern observed around the obstacle. In displacing the latter, if the front has at a certain distance, the secondary flow does not change much, but if it has at the channel end, the post-obstacle secondary flow would increase as the obstacle neared the Lock. [ABSTRACT FROM AUTHOR]

This research aims to investigate the main features of the ciliary flow of fourth‐grade fluid in a curved channel. The fluid is considered electrically conducting with a radial magnetic field effect. The constitutive relation for energy is formulated with the addition of viscous dissipation and thermal radiation. The governing system of coupled partial differential equations with extremely nonlinear expressions is simplified using the long wavelength and low Reynolds number approximations. The numerical outcomes of simplified normalized equations are obtained using the finite difference method incorporating the relaxation algorithm. The numerical outcomes regarding the influences of several physical parameters on the temperature, velocity, pumping characteristics, and stream function are examined through graphs. The outcomes reveal that fluid velocity diminishes by enhancing the magnetic parameter. Also, the temperature is enhanced by enhancing the values of the Brickman number. The current model has been used in bioengineering processes, microfluidics, and drug delivery systems. [ABSTRACT FROM AUTHOR]

High gravity (high-g) combustion can significantly increase flame propagation speed, thereby potentially shortening the axial length of aero-engines and increasing their thrust-to-weight ratio. In this study, we utilized the large eddy simulation model to investigate the combustion characteristics and flame morphology evolution of premixed propane–air flames in a channel with a backward-facing step. The study reveals that both the increase in centrifugal force and flow velocity can enhance pressure fluctuations during combustion and increase the turbulence intensity. The presence of centrifugal force promotes the occurrence of Rayleigh–Taylor instability (RTI) between hot and cold fluids. The combined effects of RTI and Kelvin–Helmholtz instability (KHI) enhance the disturbance between hot and cold fluids, shorten the fuel combustion time, and intensify the dissipation of large-scale vortices. The increase in fluid flow velocity can raise the flame front’s hydrodynamic stretch rate, thereby enhancing the turbulence level during combustion to a certain extent and increasing the fuel consumption rate. When a strong centrifugal force is applied, the global flame propagation speed can be more than doubled. Within a certain range, the increase in high-g field strength can enhance the intensity of RTI and accelerate the transition of RTI to the nonlinear stage.

Owing to extensive construction of dams, the impact of backwater on flow may lead to navigation or flood control issues in curved channels. To date, the impact of backwater on the water surface profile in curved channels remains unknown and requires investigation. In this study, experiments were conducted in a glass-walled recirculating flume with a length of 19.4 m, a width of 0.6 m, and a depth of 0.8 m, and the impact of backwater on the water surface profile in a 90° channel bend was investigated. The experimental results showed that the backwater degree had a significant impact on the transverse and longitudinal flow depth distributions in the bend. The transverse slope of the flow (Jr) increased linearly with an increase in the Froude number of the approach flow upstream of the bend. Jr increased with the longitudinal location parameter ξ when −0.2

This study attempts to analyze the effect of diverse parameters of the peristaltic flow of second grade dusty fluid through a curved configuration. Stream function conversions are used to model the separate system of equations for the dust particles and fluid. The Perturbation technique is used to get the analytical solutions and the results are verified through graphs. It is noticeable that the trapped bolus, compresses both the dust particles and fluid with an increase in 'the second grade parameter'. Moreover, a surge in 'the Reynolds number' Re effects the bolus trapped in the lower portion of the channel for fluid. Decrement in the velocity is observed with a rise in 'the wave number' - and 'the second grade parameter' α1. [ABSTRACT FROM AUTHOR]

AbstractOver the last decade, research on nanofluids has grown at a breakneck pace. As part of their nanofluid research, researchers have recently attempted to use hybrid nanofluids, made by combining different nanomaterials. The novelty of this analysis is to inspect the consequences of entropy generation on the peristalsis of a hybrid nano-liquid via a curved conduit with homogeneous and heterogeneous chemical reactions. Hybrid nanofluid is formed of copper and iron oxide nanomaterials added to water. Furthermore, the simplified model also considered the Hall current, viscous dissipation, and electrical resistance heating effects. The Hamilton–Crosser thermal conductivity model is used to study the nanomaterials shape effects (i.e. sphere, platelet, and blade) on the thermal features of hybrid nano-liquids. Mathematical expressions for the flow problem are simplified by employing the small wave and Reynolds numbers assumptions, which are then resolved analytically and numerically. Analytical results are used to scrutinize the impacts of several included quantities on the flow and thermal characteristics, chemically reactive concentration, and entropy creation. It is found that with a rise in Hartmann number, the velocity reduces, whereas an improvement is noted in temperature and entropy production for large values of Hartmann number. The noteworthy discoveries indicate that hybrid nano-liquids exhibit enhanced thermal efficiency when compared to conventional nanofluids. Specifically, the introduction of a small quantity of ferrous oxide nanoparticles into the copper–water nanofluid led to less than 2% increase in the thermal transport rate. Additionally, it was observed that spherical-shaped nanoparticles generate more heat in comparison to platelets and blade-shaped nanoparticles. Furthermore, the homogenous reaction parameter and Schmidt number lead to a drop in the concentration profile. [ABSTRACT FROM AUTHOR]

This study developed a novel dielectric wetting microfluidic operation platform combining parallel-plate and coplanar-plate regions with a curved surface structure as the connection structure. With the new electrowetting on dielectric (EWOD) platform, “droplet pull-out” has been successfully achieved and viewed as an essential new operation for microfluidics with the dielectric wetting technique. The EWOD system is divided into a PDMS substrate top plate and an indium tin oxide (ITO) glass substrate as a bottom layer on this chip. In the parallel-plate region, the droplets can be generated and transported through the square parallel electrodes; in the single-plate area, the droplets can be pulled out from the parallel structure, transported and mixed through the common grounded coplanar electrodes. In dielectric wetting performance testing, coplanar electrodes can apply a maximum driving force of 31.22 µN to DI water and 13.38 µN to propylene carbonate (PC). This driving force is sufficient to detach the sample from the top cover and pull the sub-droplet from the parallel plate structure for DI water, PC and polyethylene glycol diacrylate (PEGDA) buffer. The novel EWOD system also possesses the advantage of precise volume control for liquid samples; the volume error of the generated droplet can be controlled within 0.1% to 2%.

The basic aim of this research is to investigate the main features of the peristaltic flow of Johnson-Segalman fluid in a curved flow channel in the presence of a homogeneous-heterogeneous reaction. The fluid is considered electrically conducting with a radial magnetic field effect. The constitutive relation for energy is formulated with the addition of viscous dissipation and nonlinear thermal radiation. The slip and flexible wall boundary conditions are taken into consideration. The lubrication technique is used for the mathematical the modelling of the problem. The solution of the resulting nonlinear system of ODE’s is computed numerically through NDSolve command of Mathematica, and graphical results are prepared for flow variables. It has been clearly noticed that flow is accelerated in the planer medium as compared to the curved channel, and the velocity of the fluid increases with a larger Weissenberg number. Moreover, the thermal profile has an inverse relation to the parameters, i.e., radiation, temperature ratio, and curvature. Furthermore, it is also observed that the magnitude of heat transfer coefficient rises significantly when a comparatively less curved channel is utilized, however, a reduction in concentration profile is witnessed in this case. Alternative impact of homogeneous and heterogeneous reactions on concentration profile are observed through graphical results. Application of the study include the usage of peristaltic pump in chemical industry and in pharmacology industry for the purpose of drug deliveries.

In this study, we investigated the influence of the induced magnetic field on the Jeffrey fluid under peristalsis through the curved channel. The governing equations, such as the continuity equation, momentum equation, and magnetic force functions, are formulated. The lengthy equations are shortened by considering the approximations of the tiny Reynolds number and the long wavelength. From the resulting reduced equations, the exact solution is determined. Graphs are used to explain the graphical results of the impact of important parameters of velocity, magnetic force function, current density, induced magnetic field, pressure rise, and stream functions. [ABSTRACT FROM AUTHOR]

This study focuses on theoretical inquiry into transition of heat and mass of flowing Casson Nanofluid in a curved channel, in two dimensions, through peristalsis. The flow is assumed to be characterised by low Reynolds number and long wavelength approximations. The coupled governing non-dimensional equations of momentum, heat and mass transfer which are solved using BVP. Various parameters related with the flow are applied to study its effect on velocity, temperature and also nanofluid concentration. Also, the consequences of thermophoretic diffusion of nanoparticles and Brownian motion are discussed. The Casson parameter's effect on velocity profile is discussed. [ABSTRACT FROM AUTHOR]

The energy loss during the beating cilia phenomenon in the human stomach causing acidity in the blood flow under certain conditions has been a serious topic in the modern medical field. In the current study, authors have focused the entropy generation effects and irreversibility comparison on the flow of cilia generated metachronal waves of Cu-blood nanofluid through a curved channel by considering the effects of viscous dissipation and externally applied magnetic field. Due to the complex nature of the stream regime, curvilinear coordinates system is taken into consideration to present the constitutive expressions for bi-dimensional flow. Due to metachronal waves generated due to row wise beating cilia, authors have employed the constraints like large wave number so that the uniform pressure can be assumed over the cross section and the low Reynolds number to neglect the inertial forces. Unsteady flow of the problem producing partial differential equations is made steady by transforming it from a fixed frame to the wave frame of reference which finally provides the system of coupled ordinary differential equations along with cilia oriented non-homogeneous boundary conditions. This system has been solved analytically by incorporating a perturbation technique (HPM) to get the expressions for velocity, stream functions, pressure gradient and thermal profile. In the whole analysis, key findings are: The magnetic field reduces the flow speed in left side of the channel but increases the temperature of the system in the whole region. Entropy of the system can be reduced by diminishing the magnetic field effects and viscous dissipation, also the magnetic field is affecting the flow in the sense of contracting the bolus size. It is concluded that entropy due to thermal transfer is less than that of the whole system. More studies on the topic can be developed by considering the microorganism effects in three dimensional geometries with cilia at the boundaries.

Dielectrophoresis technology is applied to microfluidic chips to achieve microscopic control of cells. Currently, microfluidic chips based on dielectrophoresis have certain limitations in terms of cell sorting species, in order to explore a microfluidic chip with excellent performance and high versatility. In this paper, we designed a microfluidic chip that can be used for continuous cell sorting, with the structural design of a curved channel and curved double side electrodes. CM factors were calculated for eight human healthy blood cells and cancerous cells using the software MyDEP, the simulation of various blood cells sorting and the simulation of the joule heat effect of the microfluidic chip were completed using the software COMSOL Multiphysics. The effect of voltage and inlet flow velocity on the simulation results was discussed using the control variables method. We found feasible parameters from simulation results under different voltages and inlet flow velocities, and the feasibility of the design was verified from multiple perspectives by measuring cell movement trajectories, cell recovery rate and separation purity. This paper provides a universal method for cell, particle and even protein sorting. [ABSTRACT FROM AUTHOR]

Curved micro-channels are frequently used in micro-Swiss roll combustors and other applications. The secondary flows (i.e., Dean vortices) play an important role in both the mixing performance of fuel and oxidant and the flame propagation characteristics in curved micro-channel combustors. In the present study, the helicity method was adopted and a mixing performance evaluation criterion (MPEC) was proposed to investigate the impacts of inlet velocity, nominal equivalence ratio (φ) and curvature radius on the Dean vortices and mixing performance of H 2 and air in curved micro-channels. First, it is found that with the increase of inlet velocity, the intensity of Dean vortices increases and their shape grow asymmetrical. When the inlet velocity is high enough, another pair of smaller vortices appear near the outer wall. Meanwhile, the mixing performance of H 2 and air becomes worse due to the reduced residence time of gas flow. Second, as the nominal equivalence ratio is decreased, the Dean vortices are intensified and the vortices shape become asymmetrical. Moreover, the mixing process is improved owing to the enhanced secondary flows. Thirdly, the intensity of Dean vortices increases significantly as the curvature radius is decreased. However, the mixing performance becomes worse due to the shortened length of the curved micro-channel. Finally, an empirical correlation between MPEC and the Reynolds number (Re), Dean number (De) and φ was obtained based on the numerical results, which may provide a guidance for the design and operation of curved micro-channel combustors. • Mixing performance in curved micro-channels depends on intensity of Dean vortices and flow time. • Dean vortices are intensified at higher velocity but mixing is worsened due to reduced residence time. • Dean vortices are enhanced under a lower φ because of increased centripetal pressure gradient. • A smaller curvature radius leads to intensified Dean vortices but worse mixing due to insufficient mixing time. • An empirical correlation between MPEC and Re , De and φ was obtained for practical design. [ABSTRACT FROM AUTHOR]

The traditional interpolation method can’t effectively obtain the high-precision interpolation results of curved channel when the sampling channel topographic cross-section is sparse. It is urgent to study an effective new method of curved channel topographic interpolation to quantitatively analyze the channel evolution and its law. In this paper, a channel terrain interpolation method (OCGI) based on orthogonal curve grid was proposed. This method firstly performed linear interpolation along the transverse direction, and then interpolated along the longitudinal grid line, which made up for the defect of insufficient spatial distribution of longitudinal sampling points. Considering the change of river regime, the interpolation range was controlled in the area of grid distribution. The application shows that this method can give more reasonable results than that of IDW and KG methods in cross-section sampling data, and can be applied to topographic interpolation of curved channels such as the tail of the Yellow River estuary. [ABSTRACT FROM AUTHOR]

The present article concentrates on the consequences of melting heat transfer on the chemically reactive flow of Eyring-Powell liquid flow via a semi-permeable curved channel in presence of applied magnetic field. The impacts of two types of chemical reaction namely, homogeneous and heterogeneous are considered in the concentration equation. In addition, the characteristics of heat transport phenomena is also examined with the application of thermal radiation. By adopting a scheme of curvilinear coordinates system along with some appropriate similarity conversions a nonlinear ordinary differential equations is attained. The numerical simulation of the determined velocity and transport equations are estimated by using the shooting procedure. The influence of pertinent factors on the flow equations, surface drag force and rate of heat transport are thoroughly discussed via graphs and table. It is noted from the current study that surface drag force and concentration of the liquid are rises with a rising value of the melting parameter, while fluid velocity and its temperature decreases. [ABSTRACT FROM AUTHOR]

The interaction of nanoparticles with a peristaltic flow is analyzed considering a Prandtl-Eyring fluid under various conditions, such as the presence of a heat source/sink and slip effects in channels with a curvature. This problem has extensive background links with various fields in medical science such as chemotherapy and more in general nanotechnology. A similarity transformation is used to turn the original balance equations into a set of ordinary differential equations, which are then integrated numerically. The investigation reveals that nanofluids have valuable thermal capabilitises. [ABSTRACT FROM AUTHOR]

Curved channels are one of the most fundamental units of natural or artificial channels, in which there are different kinds of obstacles; these include vegetation patches, bridge piles, electrical tower foundations, etc., which are all present over a channel bend, and can significantly alter the hydrodynamic characteristics of a channel when compared to a bare bed. In this study, laboratory experiments and numerical simulations were combined to investigate the effect of a circular cylinder on the flow characteristics of a 180-degree U-shaped curved channel. Experimental data, including on water depth and three-dimensional velocity, which was obtained by utilizing acoustic Doppler velocimetry (ADV), were used to calibrate and verify the simulation results of the Reynolds-Averaged Navier–Stokes (RANS) model in the FLOW-3D software. Numerical results show that a larger cylinder diameter leads to an overall greater depth-averaged velocity at the section, a greater shear stress acting on the banks on which the cylinder is placed, and a greater increase in the depth-averaged velocity along the concave bank compared to that along the convex bank. When the diameter of the cylinder placed at the 90° section increases, two weaker circulations with the same direction are found near the water surface; for the submerged one, the two weaker circulations appear at the further downstream section, unlike the emergent one. The degree of variation degree in the shear stress acting on the banks is larger than that of the flowrate. As the flowrate increases or the radius of curvature decreases, the secondary flow intensity correspondingly elevates. However, the curvature radius of the curved channel plays a more important role in the secondary flow intensity than the flowrate does. For both the emergent and submergent cylinders, the large cylinder produces a greater secondary flow strength, but the emergent one has a greater secondary flow strength than the submergent one. In summary, the present study provides valuable knowledge on the hydrodynamics of flow around emergent and submergent structures over a curved channel, which could improve the future design of these structures. [ABSTRACT FROM AUTHOR]

A side weir is a hydraulic control structure used in irrigation and drainage systems and combined sewer systems. The Piano Key Weir (PKW) is a new type of long crest weirs that have a relatively simple structure and high economic efficiency structures. Due to the advantages of this weirs, it is necessary to study and investigate the Scour around of these structures as a side-weir. The present study focuses on investigate the scouring around the piano key Side weirs of the Type A at a 30° Section of a 180° Alluvial curved channel for clear water conditions. The results showed that at the end of the Side weir, longitudinal bar in the middle of the main channel and a scour hole close to the outer bank are formed because of the changes in shear stress field. The depth of clear-water scour increases by time and approaches the equilibrium state asymptotically depending on approach flow velocity. The equilibrium depth of scour depends on the dimensionless parameters of flow intensity, flow shallowness, weir crest height, side weir length and the maximum value of scour depth occurs at a depth when the approach flow intensity is equal to 1.0. Also, the scour equilibrium depth in the dimensionless ratio increased L/rc = 0.175 compared to L/rc = 0.125 in different flow velocity of 12 to 35%, 10 to 39% and 18 to 26%, respectively.

Side weir is a hydraulic structure within a channel which is usually used to discharge excess water, to divert the flow, and to regulate water surface levels in rivers and irrigation and drainage networks. In general, piano key weirs (PKW) have been used as weirs perpendicular to the flow direction in straight channels. However, the use of the PKW as a side weir in the outer arch of the channels is a new approach to enhance the weir's performance. In this study, 289 tests were first performed on the B-type rectangular side piano key weir (RSPKW) at two arc angles of 30 and 120°. Then, Fuzzy Inference System (FIS), Adaptive Neuro-Fuzzy Inference System (ANFIS), ANFIS and Teaching Learning Based Optimization (TLBO), ANFIS and Grasshopper Optimization Algorithm (GOA), Extreme Learning Machine (ELM) and Outlier Robust ELM (ORELM) models were used to predict the weir discharge coefficient. The results showed that two optimization models of TLBO and GOA increased the accuracy of the ANFIS model. The results showed that the ANFIS-GOA model has accuracy of Root Mean Squared Error (RMSE) = 0.0361, Coefficient of determination (R2) = 0.9772, and Kling Gupta coefficient (KGE) = 0.9858. The ANFIS-TLBO, ANFIS, and FIS models were ranked, respectively. Also, the results showed that ELM and ORELM models have accuracy close to ANFIS-GOA and can be a suitable alternative for complex fuzzy models. According to the statistical analysis, it was found that the parameters of the ratio of weir height to flow depth at the upstream edge of weir (P/h 1), arc angle (α), and the ratio of height of the foundation to the main channel width (p d /B) had the greatest role in the development of the models, respectively. • Discharge coefficient is one of the important parameters in the design of B-type RPKSW. • For modeling, four types of intelligent models were used for modeling the discharge coefficient of B-type RPKSW. • For the first time, Novel hybrid models (ANFIS-GOA and ANFIS-TLBO) proposed for discharge coefficient (Cd) of B-type RPKSW. • Compared predictive capability of four different models (FIS, ANFIS, ANFIS-GOA, ANFIS-TLBO). [ABSTRACT FROM AUTHOR]

Tidal bore is a special and intensive form of flow movement induced by tidal effect in estuary areas, which has complex characteristics of profile, propagation and flow velocity. Although it has been widely studied for the generation mechanism, propagation features and influencing factors, the curved channel will complicate the characteristics of tidal bore propagation, which need further investigation compared with straight channel. In this study, the flume experiments for both undular and breaking bores' propagation in curved channel are performed to measure the free-surface elevation and flow velocity by ultrasonic sensors and ADV respectively. The propagation characteristics, including tidal bore height, cross-section surface gradient, tidal bore propagation celerity, and flow velocity are obtained for both sides of the curved channel. And three bore intensities are set for each type of tidal bores. The free-surface gradients are consistently enlarged in high-curvature section for undular and breaking bores, but have distinct behaviors in low-curvature section. The spatial distributions of tidal bore propagation celerity and flow velocity are compared between concave and convex banks. This work will provide experimental reference for engineering design of beach and seawall protection, erosion reduction and siltation promotion in estuary areas with the existence of tidal bores. [ABSTRACT FROM AUTHOR]

Curved channels and aquatic vegetation are commonly present in the riverine environment. In this study, the effects of vegetation density and distribution on the hydrodynamic characteristics of a mixed layer developed over a 180-degree curved channel were investigated through flume experiments. Wooden sticks were used to simulate rigid vegetation distributed along the half side of the channel, and a 200 Hz acoustic Doppler velocimeter (ADV) was employed to measure the three-dimensional instantaneous velocity at five selected cross sections along the curved channel. Experimental results show that the vegetation covering the half of the channel significantly affects the hydrodynamic structure of the curved channel flow, and the unequal vegetation resistance induces the K-H instability at the vegetation and non-vegetation interface, resulting in a standard hyperbolic tangent function of streamwise velocity distribution along the lateral direction. The influence of curve position on turbulence kinetic energy is far greater than that of vegetation density and vegetation distribution. The peak value of turbulent kinetic energy is comprehensively affected by vegetation density and distribution, and the peak position of turbulent kinetic energy at the interface is changed by different vegetation distribution. The combined effect of the curve and the partly covered vegetation increases the mixing between the water bodies, enhancing turbulent kinetic energy, and vegetation along the concave bank plays a more significant role. For turbulent bursting, the inward and outward interactions are mainly bursting events in the vegetation area, while ejections and sweeps are dominant in the non-vegetation area. However, the critical vegetation condition to initiate large-scale coherent structure (LSS) in the mixed layer and the influence of flexible vegetation need to be further studied in the future. [ABSTRACT FROM AUTHOR]

The energy loss during the beating cilia phenomenon in the human stomach causing acidity in the blood flow under certain conditions has been a serious topic in the modern medical field. In the current study, authors have focused the entropy generation effects and irreversibility comparison on the flow of cilia generated metachronal waves of Cu-blood nanofluid through a curved channel by considering the effects of viscous dissipation and externally applied magnetic field. Due to the complex nature of the stream regime, curvilinear coordinates system is taken into consideration to present the constitutive expressions for bi-dimensional flow. Due to metachronal waves generated due to row wise beating cilia, authors have employed the constraints like large wave number so that the uniform pressure can be assumed over the cross section and the low Reynolds number to neglect the inertial forces. Unsteady flow of the problem producing partial differential equations is made steady by transforming it from a fixed frame to the wave frame of reference which finally provides the system of coupled ordinary differential equations along with cilia oriented non-homogeneous boundary conditions. This system has been solved analytically by incorporating a perturbation technique (HPM) to get the expressions for velocity, stream functions, pressure gradient and thermal profile. In the whole analysis, key findings are: The magnetic field reduces the flow speed in left side of the channel but increases the temperature of the system in the whole region. Entropy of the system can be reduced by diminishing the magnetic field effects and viscous dissipation, also the magnetic field is affecting the flow in the sense of contracting the bolus size. It is concluded that entropy due to thermal transfer is less than that of the whole system. More studies on the topic can be developed by considering the microorganism effects in three dimensional geometries with cilia at the boundaries. [ABSTRACT FROM AUTHOR]

The nanoparticles are frequently used in biomedical science for the treatment of diseases like cancer and these nanoparticles are injected in blood which is transported in the cardiovascular system on the principle of peristalsis. This study elaborates the effects of Lorentz force and joule heating on the peristaltic flow of copper and iron oxide suspended blood based nanofluid in a complex wavy non-uniform curved channel. The Brinkman model is utilized for the temperature dependent viscosity and thermal conductivity. The problem is formulated using the fundamental laws in terms of coupled partial differential equations which are simplified using the creeping flow phenomenon. The graphical results for velocity, temperature, streamlines, and axial pressure are simulated numerically. The concluded observations deduce that the solid volume fraction of nanoparticles reduces the velocity and enhance the pressure gradient and accumulation of trapping bolus in the upper half of the curved channel is noticed for temperature dependent viscosity. [ABSTRACT FROM AUTHOR]

Elder's equation for the longitudinal dispersion coefficient in two-dimensional solute transport analysis cannot be applied to curved channels because the vertical distribution of the longitudinal velocity does not obey the logarithmic law in the bends of an open channel. In this study, a two-dimensional longitudinal dispersion coefficient based on an equation that can appropriately describe the vertical distribution of flow velocity in open-channel bends is derived theoretically. The proposed equations for the vertical velocity distribution and dispersion coefficient are compared and verified with values measured from two different types of open channels, i.e., a laboratory channel and a natural-like channel. The increase in the longitudinal dispersion coefficient based on the difference in the vertical distribution of the flow velocity is evaluated quantitatively. In terms of the longitudinal dispersion coefficient, no significant difference is observed between the observed dispersion coefficient based on the concentration data and the coefficient value calculated using the equation proposed in this study. The dispersion equation proposed in this study can be easily applied to assign the value of the longitudinal dispersion coefficient for the two-dimensional mixing modelling in bends using basic hydraulic factors. [ABSTRACT FROM AUTHOR]

This article presents a new approach to determining the viscosity of Newtonian fluid. The approach is based on the analysis of the secondary Dean flow in a curved channel. The study of the flow patterns of water and aqueous solutions of glycerin in a microfluidic chip with a U-microchannel was carried out. The advantages of a microfluidic viscometer based on a secondary Dean flow are its simplicity, quickness, and high accuracy in determining the viscosity coefficient of a liquid. A viscosity image in a short movie represents fluid properties. It is revealed that the viscosity coefficient can be determined by the dependence of the recirculation angle of the secondary Dean flow. The article provides a correlation between the Dean number and the flow recirculation angle. The results of the field experiment, presented in the article, correlate with the data obtained using computational fluid dynamics and allow for selecting parameters to create microfluidic viscometers with a U-shaped microchannel. [ABSTRACT FROM AUTHOR]

The bending section of the restricted channel is one of the most accident-prone areas for inland ships, but few clear investigations on the curvature effect have been conducted till now. Therefore, this paper presents numerical research of the curvature effect in confined bending channels on ship hydrodynamics. The unsteady Navier–Stokes equations closed by the realizable K-Epsilon turbulence model are utilized to simulate the flow around a three-dimensional inland ship. A mesh verification analysis is performed to select the most suitable grid size, and the CFD model is validated in a regular confined channel by comparing the numerical resistance forces with those from experiments. The impacts of the channel slope angle, channel radius, ship type (ship length), and current velocity in curved channels on ship hydrodynamics are studied with their influence patterns and mechanisms being analyzed in detail. Results show that channel radius only affects the yaw moment much, whereas ship hydrodynamics are greatly sensitive to the slope angle only when the angle is below a certain threshold value. Compared with short ships, much stronger spiral currents can be noticed passing through long ships in the same channel configuration. Current velocity affects both resistance and yaw moment a lot, with a critical current velocity for sway force. [ABSTRACT FROM AUTHOR]

A theoretical study has been developed to explore peristaltically deformable curved channel flow of Sisko nanofluid with double-diffusive (thermal and concentration) convection. Such consideration supports the flow of fluid in biological vessels and arteries to transport the food contents, oxygen, waste products, heat, blood and several other nutrients to the body. The flow stream is regulated and restricted in laminar region by considering long wavelength (d≪λ→∞) and low Reynolds number (Re→0) in terms of velocity, temperature, concentration and nanoparticle volume fraction fields. Moreover the mathematical expressions are listed for mixed convection and viscous dissipation aspects. The outcomes of influential dynamic parameters are sketched as graphical flow patterns with focus towards double-diffusive convection. Computational technique NDSolve in Mathematica is employed. The results for classical Newtonian fluid are captured as a special case of this analysis. The upshots of this investigation can be supportive for an enhancement of gastrointestinal movements and pumping in several engineering devices.

The peristaltic phenomenon has intended the researcher’s attention due to its extensive applications in bio-mechanics, industries and biological sciences. The applications of peristaltic transport problems are observed in the transportation of cilia, food mixing in digestive tract, small blood vessels vasomtion, urine transportation etc. Following to such motivating applications in minds, this theoretical analysis presents the peristaltic flow of magnetized Jeffery fluid through accounted by curved channel in presence of heat transfer. The assumed flow is confined by different wave frames. The heat transfer inspection has been performed by utilizing the non-linear thermal radiation and joule heating features. The curvilinear coordinate system is used to model the two dimensional, laminar and incompressible Jeffrey fluid with peristaltic phenomenon. The partial differential equations are transformed into ordinary differential equations in view of appropriate quantities. The implementation of wave length with long magnitude and the assumptions of smaller Reynolds assumptions, the governing system of ordinary system is solved numerically by using shooting technique. The dynamic of involved quantities and physical variables is observed carefully. A declining observation in the temperature in all forms of waves has been noticed for increasing the viscoelastic parameter. The heat transfer coefficient for all waves enhanced for the radius of curvature. Moreover, the velocity of the fluid declines in the lower half of the channel and rises near upper wall of the curved channel due to magnetic parameter.

This article analyses the effects of differently shaped copper nanoparticles on mixed convection peristaltic transport of water-based nanofluid via a curved channel. Momentum and energy equations are derived and simplified under long wavelength and physically small Reynolds number assumptions. Experimentally tested correlations related to thermophysical properties of nanofluids are incorporated into these equations to examine the effects of nanoparticles. Obtained equations are further transformed into dimensionless forms by utilizing dimensionless variables. Numerical solutions are computed using software Mathematica. Effects of physical parameters on trapping phenomena, pressure gradient, velocity and temperature fields are examined. It is observed that the magnitude of the axial pressure gradient and heat transfer rate is maximum for nanofluid suspended with platelet shaped nanoparticles.

Dielectrophoresis technology is applied to microfluidic chips to achieve microscopic control of cells. Currently, microfluidic chips based on dielectrophoresis have certain limitations in terms of cell sorting species, in order to explore a microfluidic chip with excellent performance and high versatility. In this paper, we designed a microfluidic chip that can be used for continuous cell sorting, with the structural design of a curved channel and curved double side electrodes. CM factors were calculated for eight human healthy blood cells and cancerous cells using the software MyDEP, the simulation of various blood cells sorting and the simulation of the joule heat effect of the microfluidic chip were completed using the software COMSOL Multiphysics. The effect of voltage and inlet flow velocity on the simulation results was discussed using the control variables method. We found feasible parameters from simulation results under different voltages and inlet flow velocities, and the feasibility of the design was verified from multiple perspectives by measuring cell movement trajectories, cell recovery rate and separation purity. This paper provides a universal method for cell, particle and even protein sorting.

In electrowetting-on-dielectric (EWOD) platform, the transfer of droplets from the EWOD boundary region (top plate and bottom plate) to the open region is challenging. The challenge is due to the resistance-like surface tension, friction from the top-plate edge, and the so-called boundary. For this purpose, we designed the top plate to minimize the friction resistance at the boundary. The experiment focused on Gibb's formula and successfully transferred the liquid droplet between the top plate and bottom plate boundary region under a high voltage environment. The threshold voltage for the successful transportation of the droplet between the boundary is 250 V which provides strong pressure to drive the droplet. [ABSTRACT FROM AUTHOR]

This article communicates peristalsis of Jeffrey material in curved geometry. Here, material has temperature-dependent thermal conductivity and viscosity. Mathematical modeling of an inclined magnetic field in curved configuration has been presented in this article. Irreversibility effects have been analyzed through entropy generation. Slip conditions are entertained both for velocity and thermal fields. Problem is first reduced in wave frame and then lubrication approach has been utilized. Numerical solution of dimensionless problem is obtained and important parameters of curiosity are examined. It is noticed that velocity enhances for higher viscosity whereas temperature decreases for higher thermal conductivity coefficient. Velocity of the flow is maximum for inclination of magnetic field to be zero and it is minimum for ϑ o = 90 ∘. Heat transfer parameter enhances both for thermal conductivity parameter and Hartmann number. Temperature is high for curved configuration when compared with straight channel. It is observed that entropy remains unchanged in center of the channel and it is maximum near the channel walls. Entropy generation decays near the channel walls by higher viscosity and thermal conductivity parameters. However, entropy is more for higher inclination of magnetic field. [ABSTRACT FROM AUTHOR]