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Fluid-based methods for particle sorting demonstrate increasing appeal in many areas of biosciences due to their biocompatibility and cost-effectiveness. Herein, we construct a microfluidic sorting system based on a swirl microchip. The impact of microchannel velocity on the swirl stagnation point as well as particle movement is analyzed through simulation and experiment. Moreover, the quantitative mapping relationship between flow velocity and particle position distribution is established. With this foundation established, a particle sorting method based on swirl induction is proposed. Initially, the particle is captured by a swirl. Then, the Sorting Region into which the particle aims to enter is determined according to the sorting condition and particle characteristic. Subsequently, the velocities of the microchannels are adjusted to control the swirl, which will induce the particle to enter its corresponding Induction Region. Thereafter, the velocities are adjusted again to change the fluid field and drive the particle into a predetermined Sorting Region, hence the sorting is accomplished. We have extensively conducted experiments taking particle size or color as a sorting condition. An outstanding sorting success rate of 98.75% is achieved when dealing with particles within the size range of tens to hundreds of micrometers in radius, which certifies the effectiveness of the proposed sorting method. Compared to the existing sorting techniques, the proposed method offers greater flexibility. The adjustment of sorting conditions or particle parameters no longer requires complex chip redesign, because such sorting tasks can be successfully realized through simple microchannel velocities control. [ABSTRACT FROM AUTHOR]

We report on viscous adhesion measurements conducted in sphere-plane geometry between a rigid sphere and soft surfaces submerged in silicone oils. Increasing the surface compliance leads to a decrease in the adhesive strength due to elastohydrodynamic deformation of the soft surface during debonding. The force-displacement and fluid film thickness-time data are compared to an elastohydrodynamic model that incorporates the force measuring spring and finds good agreement between the model and data. We calculate the pressure distribution in the fluid and find that, in contrast to debonding from rigid surfaces, the pressure drop is non-monotonic and includes the presence of stagnation points within the fluid film when a soft surface is present. In addition, viscous adhesion in the presence of a soft surface leads to a debonding process that occurs via a peeling front (located at a stagnation point), even in the absence of solid–solid contact. As a result of mass conservation, the elastohydrodynamic deformation of the soft surface during detachment leads to surfaces that come closer as the surfaces are separated. During detachment, there is a region with fluid drainage between the centerpoint and the stagnation point, while there is fluid infusion further out. Understanding and harnessing the coupling between lubrication pressure, elasticity, and surface interactions provides material design strategies for applications such as adhesives, coatings, microsensors, and biomaterials. [ABSTRACT FROM AUTHOR]

We intend to analyze the influences of heat dissipation and heat generation on steady nanofluid stagnated flow along an extending surface along with thermal boundary layers. Water-based Cu and Al2O3 nanoparticles are considered. Moreover, the mechanism of injection/suction has been analyzed for such flows. Fundamental governing equations for the flow of an isotropic in-compressible thermally radiative single-phase nanofluid are defined by the set of nonlinear Partial Differential Equations (PDEs) which are transmuted to Ordinary Differential Equation (ODEs) and dealt with numerically by using Runge–Kutta (RK) fourth-order adopting shooting technique that gives approximate simulations. The numerical findings are illustrated as graphical and tabular representations after a careful parametric examination of determined parameters is carried out. The current outcomes specify that the velocity profiles decrease under the influence of magnetic strength while heat distribution positively changes under the effect of magnetic strength, heat source, radiative term and Biot number quantity. The temperature profiles behave negatively with the thermal Grashof number and Prandtl number. Moreover, the comparative simulations of the ongoing study with existing the literature for ensuing the obtained simulations have been worked out. [ABSTRACT FROM AUTHOR]

This study explains the steady flow of a hybrid nanofluid due to a permeable shrinking sheet close to a stagnation region with suction/injection. By proper transformations, the leading differential equations, partial in nature, are reduced to nonlinear differential equations with a single independent variable. A combination of the Runge–Kutta method and a shooting technique is applied to unravel those nonlinear equations. The effects of various parameters on the flow and thermal fields are presented graphically and analyzed. Also, for various physical parameters, wall shear stress, and the heat transport coefficient are computed numerically and discussed in detail. For the boundary value problem, multiple (two) solutions are obtained for a definite choice of governing parameters. Hence, a stability analysis is carried out, indicating that the first branch of the solution is stable and physically realistic. The unsteady equations are considered for implementing the stability analysis. Furthermore, in a hybrid nanofluid flow, a higher heat transfer rate than a nanofluid is observed. The separation of the boundary layer occurs. Also, with a rise in the value of the nanoparticle volume fraction of Al2O3, the critical value of the suction parameter increases. [ABSTRACT FROM AUTHOR]

In this study, we have explored the stagnation point flow of magnetohydrodynamic Casson and Maxwell flows through an extending surface. Influences of various physical factors on the Casson and Maxwell flows are discussed in this article. Convergence analysis of the applied technique called HAM is shown in the figures. Comparison of the current analysis with the earlier available literature is also done and has found an outstanding alignment. It is found that the direct relation of angle of inclination with magnetic parameter has significantly reduced the Casson flow as compared to the Maxwell flow. The stagnation number has greater impact on the Casson flow as compared to the Maxwell flow. The thermal and concentration buoyancy parameters have significantly improved the velocity profile of the Maxwell fluid as compared to the Casson fluid. Because of the convective boundary condition, Biot number improved the temperature. Also, the thermal radiation, and non-uniform heat source/sink factors have increased the temperature profile of the fluids. These impressions are superior for the Casson fluid associated to the Maxwell fluid. The greater thermophoresis parameter has growing impact on concentration profile, while the greater Schmidt number, Brownian motion, and chemical reaction parameter have inverse relation with the concentration profile. [ABSTRACT FROM AUTHOR]

The inclined impinging jets owing to higher efficiency are widely used to disperse concentrated and transient heat loads. The temperature and heat transfer characteristics of jet cooling vertical hot plate at different inclinations are experimentally investigated. Experiments are performed to investigate the area average heat transfer over a flat surface of 600 × 300 mm2 placed at different location (z) of 3−20 d from the jet. The investigation is employed for Reynolds number based on hydraulic diameter of 11.5 mm ranging from 10,000 to 75,000. The orientation of the jet varies from 15° to 75°. The study aims to investigate the influence of jet orientation at different area locations on the surface from the point of impingement. The effect in stagnation region with different jet tilt is investigated. The area average temperature variation and characteristic temperature contours with increasing surface area and inclination is delineated. The characteristics of heat transfer on the surface's periphery are studied. Heat transfer increases by 40% at lower tilt angle as the jet is displaced from 20 to 6 d, whereas the maximum average Nu occurs at higher inclination. The available Nusselt numbers in inclined jet are compared with present experimental results. A new empirical correlation is developed for a complete range of z/d, Re and large radial span. [ABSTRACT FROM AUTHOR]

The heat transfer characterisation of the three-phase local thermal non-equilibrium analysis due to the nanofluid (solid particle phase and the base fluid phase) and the absorbing phase (due to the porous surface) is performed for a third-grade nanofluid impinging over a receding surface. The mathematical formulation of the physical model includes the Rivlin–Ericksen tensor for fluids of grade three with appropriate restriction to viscous flows and also incorporates the Buongiorno nanofluid model for studying the impact of thermophoresis and Brownian motion. The resultant governing time-dependent partial differential equations has been converted to ordinary differential equations by applying similarity transformation. The computational results are obtained using the finite-difference approach in the Matlab software. The non-Newtonian and the time-dependent flow phenomena demands an additional boundary condition to ensure the uniqueness of the solution. With a general third-grade assumption with the wall shrinking and unsteadiness, the resultant equations govern the occurrence of dual solution in the obtained numerical results. The stability investigation reports the existence of multiple (dual) solutions due to the unsteadiness imparted in the flow and the flow behaviour of both the stable and unstable solutions are revealed. The boundary layer characteristics are explored for various vital physical parameters, such as material parameter, porous permeability parameter, Brownian motion parameter, thermophoresis parameter, inter-phase heat transfer coefficient, modified thermal capacity ratio, modified thermal diffusivity ratio and buoyancy ratio parameter. The temperature distribution across different phases is analysed for the stable solutions. [ABSTRACT FROM AUTHOR]

Different transition to turbulence routes for the flow around blunt bodies are possible. Non-modal amplification of perturbations via the lift-up effect has recently been explored to explain transition near the stagnation point in axisymmetric bodies. However, only perturbations already present in the boundary layer can be amplified, and the mechanisms by which free-stream perturbations enter the boundary layer have not yet been fully explored. In this study, we present an investigation of how disturbances enter the boundary layer via the stagnation point. This linear mechanism is expected to dominate over non-linear mechanisms previously identified on the formation of boundary layer perturbations at low turbulence intensity levels. A parametric investigation is presented, revealing trends with Reynolds and Mach numbers. [ABSTRACT FROM AUTHOR]

In current work, the unsteady stagnation point's flow on a special third-grade fuzzy hybrid (Al2O3 + Cu/SA) nanofluid (HNF) through a permeable convective shrinking/stretching sheet has been scrutinized. In addition, the adverse consequences of heat source, viscous dissipation, nonlinear thermal radiation, and fuzzy nanoparticle volume fraction are likewise taken into consideration. Non-linear coupled partial differential equations (PDEs) get transformed into ordinary differential equations (ODEs) using an effective similarity transformation. After that, the ODEs are numerically solved using the bvp4c algorithm. Regarding validation, the present results align with earlier published research. The effects of heat distribution, flow rate, Nusselt number, and skin friction coefficient on hybrid nanofluid dynamics are explored using graphical and tabular forms. The nanoparticle volume fraction is considered a triangular fuzzy number (TFN) [0, 5%, 10%]. With the use of TFNs, ODEs are transformed into fuzzy differential equations (FDEs). The TFNs are controlled using a widely used ζ - cut technique and ζ - cut ∈ [0, 1], which requires minimal computational effort to examine their dynamical performance. Also, the comparison of Al2O3/SA, Cu/SA and Al2O3 + Cu/SA through the fuzzy membership functions (MFs). The fuzzy MFs show that the hybrid nanofluid (Al2O3 + Cu/SA) in terms of rate of heat transfer is better than both Cu/SA and Al2O3/SA nanofluids. [ABSTRACT FROM AUTHOR]

In recent times, the interaction of nanoparticles has significantly enhanced the thermal association of heat transport. This phenomenon plays a crucial role in hydraulic systems, particularly in the context of lubrication and its associated consequences on mass and heat transport. Current studies have focused on investigating the thermal effects of a third-order nanofluid on a lubricated stretched surface near an analytical stagnation point. The lubrication process involves the use of a thin, adjustable coating of lubricant fluid. To analyze this complex system, we employ the Buongiorno model and explore thermophoresis and the Brownian motion phenomenon. For deriving analytical results of updated boundary layer ordinary differential equations, we rely on the dependable and effective hybrid homotopy analysis method (HHAM). To exhibit the effectiveness of our study, we provide a numerical comparison. Based on theoretical flow assumptions, we establish a range of flow parameters. In the presence of lubrication, we physically examine how these parameters affect temperatures, velocities, concentration, and other relevant quantities of thermal interest. These new findings have practical applications in polymer production, heat transmission, and hydraulic systems. [ABSTRACT FROM AUTHOR]

In the machining of high-strength materials, shear localization in serrated chip formation leads to time-varying thermo-mechanical loads exerted by the cutting tool on the machined surface. This results in periodic changes to surface integrity. This article explains the formation mechanism of machined surface microfeatures and residual stress fluctuations associated with serrated chip formation, based on a finite element model of machining Waspaloy using the coupled Eulerian-Lagrangian method. The model is validated by comparing the simulation results with experimentally measured chip morphologies and machined surface profiles. During machining with a constant chip thickness, the machined surface exhibits a uniformly distributed residual stress pattern along the cutting velocity direction. However, increased cutting velocity and serrated chip formation cause periodic shear bands, leading to time-varying location of the stagnation point on the cutting tool. This results in variations in the workpiece material volume and the thermo-mechanical loads in the plowing region. After machining, the periodical variation in the elastic recovery of the plowed material at the bottom of the cutting tool creates waveforms on the finished surface, accompanied by fluctuations in residual stress at the same frequency as chip serration. The simulations quantitatively determine the normal/shear contact force at the tool-workpiece interfaces to reveal the effect of the time-varying stagnation point location on surface topographies and residual stress distributions. [ABSTRACT FROM AUTHOR]

Three preconditioning methods suggested by Eriksson, Choi, Merkel, and Turkel have been utilized within a 2D upwind Euler flow solver designed for unstructured grids. These strategies efficiently address the complexities of steady inviscid flows at low Mach numbers. The conservative formulations of the preconditioning matrices are rigorously derived. This implementation enables a more accurate evaluation of high‐gradient flows. Extensive simulations are conducted on various flow scenarios, including flows over the NACA0012 airfoil, a multi‐element three‐element airfoil, and a smooth bump with varying Mach numbers, to validate the effectiveness of the aforementioned preconditioning strategies. Compared to the non‐preconditioned approach, the results demonstrate significant accuracy and convergence speed improvements for all three preconditioning methods. These strategies exhibit remarkable efficiency for low Mach and incompressible flows. Among the three approaches, the Turkel preconditioner stands out with its optimal condition number, leading to superior performance. For low Mach numbers, convergence is accelerated by up to 88%, while at transonic speeds, it still achieves a notable 38% increase in convergence speed. Additionally, the preconditioning techniques preserve solution accuracy near challenging stagnation points. This study establishes a unified conservative framework for assessing preconditioning approaches and highlights their ability to resolve the complex fluid physics of low Mach number flows on unstructured grids. The findings underscore the significance of employing such strategies to enhance accuracy and computational efficiency in evaluating high‐gradient flows. [ABSTRACT FROM AUTHOR]

Comprehending and measuring heat transfer (HT) mechanisms in groundwater systems is crucial for tackling diverse issues and maximizing the use of subterranean resources while reducing ecological consequences. Groundwater flow is frequently simulated and predicted using mathematical models, such as Darcy's law, which governs the movement of fluids through porous media. Thus, a theoretical analysis of HT is therefore carried out for a time‐independent 3D power‐law (PL) nanofluid (NF) flow on the stretching rotating porous disc near the stagnation region, subject to convective boundary condition, using the MHD, heat source/sink, and thermal radiation effects. A numerical simulation via the Keller Box method is performed using PDEs as the mathematical model for the suggested problem. Investigations are conducted on how several classes of pertinent characteristics affect temperature, velocity, surface drag forces, and HT rate. It has been observed that the radial velocity of the disc increases with an escalation in the permeability of the porous media whereas the azimuthal velocity, however, tends to decrease. Additionally, the rate at which heat is transferred escalates as the radiation and heat source/sink parameter's strength increases whereas it decays along the Prandtl and Biot numbers. Lastly, the present study's results can be applied to understand the thermal impact on seepage of groundwater, geothermal energy extraction, containment systems for landfills and waste, design of subsurface infrastructure, aquifer thermal energy storage, and impact assessment against climate change. [ABSTRACT FROM AUTHOR]

We studied a candidate TPS (thermal protection system) material for reusable re-entry space vehicle applications. The material was based on a high-temperature-resistant material called Cerakwool. A total of six specimens were fabricated with substrate densities of 0.45 g/cm3, 0.40 g/cm3, and 0.35 g/cm3, with two specimens for each density. All specimens were coated with high-emissivity TUFI (toughened unpiece fibrous insulation), with coating thicknesses ranging from 445 to 1606 µm. The specimens were tested using an HVOF (high-velocity oxygen fuel) material ablation test facility. For each density specimen pair, one specimen was tested at 1 MW/m2 and the remaining one was tested at 0.65 MW/m2. The average stagnation point temperature for specimens tested at 1 MW/m2 was ~893 °C, approximately 200 °C higher than those tested at 0.65 MW/m2. This suggests a ~200 °C increase in stagnation point temperature for a 0.35 MW/m2 rise in incident heat flux. During the tests, internal temperatures were measured at three locations. For all tested specimens, regardless of heat flux test conditions and density, the temperature at ~40 mm from each specimen's stagnation point remained around or below 50 °C, well within the 180 °C design limit set for the TPS back face temperature. Post-test visual inspections revealed no signs of ablation or internal damage, confirming the material's reusability. [ABSTRACT FROM AUTHOR]

The local heat transfer characteristics of circular multiple air jet impingement on semicircular concave surface were studied experimentally. For constant Reynolds number (Re = 9,000), the effect of jet to concave surface spacing (z/d = 1, 4.2, 6), ratio of curvature (D/d = 4.28, 6, 8.6), jet-to-jet spacing (s/d = 2.4, 4, 5.6), and number of jets were considered. The local heat transfer characteristics were determined by using infrared thermal camera and thin foil method. Lower curvature value ratio (D/d = 4.28) resulted higher average heat transfer coefficient due to broader spread of heat transfer distribution, whereas higher curvature ratio (D/d = 8.6) resulted in lower average heat transfer coefficient due to steeper heat transfer distribution in the stagnation area. At lower D/d, z/d, and s/d with seven jet configuration, the heat transfer coefficients were found effective as compared to other configurations due to broad heat transfer distribution and less interaction between the jets. At given D/d and s/d configuration, the stagnation Nu at θ = 0° do not coincide with jet hole center axis and this shift is more pronounced at higher z/d value. This could be due to additional push before jet impinging on concave surface. The secondary peaks were observed between two neighboring stagnation regions in Nu distribution along the center longitudinal line for lower z/d and higher s/d values. This resulted due to upwash that was obtained from jet interactions related to collisions with the wall jets. The correlations of stagnation line average Nu and overall average Nu were obtained. The coefficient of variance of local heat transfer coefficient for each configuration was determined, and correlation was proposed to analyze the degree of non-uniformity. [ABSTRACT FROM AUTHOR]

These days, innovation in nanostructures, which are distinguished by their exploratory use in a variety of biological applications, is a result of the advancement of nanotechnology. Over the last few decades, advances in nanoscience, nanotechnology, and thermal engineering have culminated in the multidisciplinary topic of nanofluid technology. Novel features found in nanofluids have the potential to be applied in a wide range of fields, including biotechnology, information technology, food and agriculture, national security and defense, aerospace, the plastics and textile industries, energy and the environment, cosmetics, and health and medicine. In this analysis, energy and mass transport rate of nanoliquid with micro-rotation impacts have been discussed. Furthermore, Soret impact, radiations, and stagnation motion are discussed in detail. The boundary layer equations are converted into (ODE's) ordinary differential equations and elucidated the results numerically employing the Keller box technique. We established the enhancement in the temperature profile against the growth of thermal radiation parameter. Further, the increment in Soret factor presents concentration profile increases. The impact of Brownian motion on nanoparticles enhanced the temperature profile. This study will help to control the cooling process in industry and engineering applications. [ABSTRACT FROM AUTHOR]

The research on entropy generation in a mechanical system is quite imperative owing to its immense applications in the production of advanced cooling devices and medical appliances. The basic need on this research is how to optimize the irreversibilities within the systems and channelize that energy towards the benefit. This study elucidates the entropy generation analysis of a Casson nanofluid near a stagnation point over a lubricated vertical wall. A thin film of shear-thinning liquid with power law index of 0.5 is employed on the wall to ensure the lubrication. The effect of induced magnetic field and the chemical reaction stimulated by the activation energy is also incorporated within the flow. The non-linear PDEs of the substantive problem along with the compatible interfacial and boundary conditions are reverted into ODEs with the aid of suitable similarity transformation, and then cracked numerically using the sixth-order Runge Kutta method assisted with Nachtsheim–Swigert shooting practice. One of the significant findings reveals that the fluid friction irreversibilities in the entropy generation are diminished with the magnetic parameter and the Casson parameter, whereas the thermal irreversibility predominates over the total entropy generation for the escalating values of the activation energy parameter. [ABSTRACT FROM AUTHOR]

The article "Inviscid jets driven by pressure maxima" in the Journal of Fluid Mechanics explores the formation of fast jets in inviscid fluids near free boundaries due to pressure maxima. The study focuses on two-dimensional and axisymmetric configurations, suggesting that these jets can become infinitely long in a finite time. The research models critical jet initiation without gravity effects, providing explicit asymptotic solutions to validate numerical predictions of rapid jet formation. The study also examines the axisymmetric case, showing similar outcomes with even stronger jet accelerations. The authors present a theoretical framework for the development of fast jets near planar free boundaries in inviscid fluids, driven by dipoles that accelerate to infinite length in a finite time, with axisymmetric jets accelerating faster. [Extracted from the article]

The article in the Journal of Fluid Mechanics explores dynamic stall onset and vortex shedding in low-Reynolds-number flows, focusing on the leading edge suction parameter (LESP) and boundary enstrophy flux (BEF) as predictive criteria. High-resolution simulations of an airfoil at two Reynolds numbers reveal various unsteady flow phenomena, with BEF effectively identifying stall onset and vortex shedding events. The study underscores the significance of these criteria in comprehending low-Reynolds-number unsteady flows and their implications for flow control. The research, supported by NSF and US Air Force grants, sheds light on the dynamics of vortex shedding on airfoils at low Reynolds numbers. [Extracted from the article]

The article "Actuation manifold from snapshot data" in the Journal of Fluid Mechanics introduces a data-driven approach to analyze controlled flows using isometric mapping and neural networks. It focuses on a fluidic pinball configuration with three cylinders at Reynolds number 30, revealing a five-dimensional manifold with minimal error. The study uncovers key parameters related to vortex shedding and actuation, offering valuable insights into fluid mechanics. The document also discusses various research papers on wake analysis, vortex shedding stabilization, machine learning for fluid control, and nonlinear dimensionality reduction, providing a comprehensive overview for researchers in the field. [Extracted from the article]

This work examines the steady three-dimensional stagnation point of an electrically conducting Newtonian fluid under Oberbeck–Boussinesq approximation. This article is concerned with the boundary-layer formation over the vertical sheet. An analysis has been carried out to investigate the influence of variable fluid properties in mixed convection three-dimensional flow of viscous fluid by a vertical surface with heat transfer. The mathematical model incorporates by considering temperature-dependent variations in viscosity and thermal conductivity. The governing equations are transformed into nonlinear partial differential equations by appropriate transformation and admit local-similar solutions. The flow has to satisfy ordinary differential equations whose solution depends upon different parameters such as mixed convection parameter λ and variable viscosity θr, and c1 shows 3-dimensional motion of flow. Quantitative analysis of the flow field and heat transfer characteristics is conducted using graphs and numerical values obtained through Bvp4c MATLAB. A novel approach using Artificial Neural Networks (ANNs) has been used to accurately predict heat transfer parameters. The ANN model is trained using a comprehensive dataset obtained from numerical simulations and experimental measurements. The inputs to the ANN include relevant flow parameters such as Reynolds number, Prandtl number, and geometrical characteristics, while the outputs are the corresponding skin friction and the Nusselt number. The results indicate that the ANN model exhibits excellent predictive accuracy compared to traditional empirical correlations and computational fluid dynamics simulations. The graphical representation of emergent parameters has been explored, along with a corresponding discussion. The comparison is being made between the effects of constant and variable fluid properties. [ABSTRACT FROM AUTHOR]

In the present study, a novel flow control technique based on jet focusing and vectoring from a synthetic jet array (SJA) for controlling the wake of a bluff body is proposed and demonstrated. A numerical investigation into the flow past a square cylinder modified by the SJA has been carried out at a free stream Reynolds Number of 100. The SJA consists of four independently controlled synthetic jet actuators operating at a peak velocity of eight times the free stream and fifteen times the natural vortex shedding frequency of the square cylinder. The SJA is operated in two different regimes; a focusing regime involving phase delay (Δ φ) with non-linear variation between the actuators and a vectoring regime with a linear phase delay without changing the geometric or operating parameters of the SJA. It has been found that jet focusing is able to reduce the coefficient of drag by as much as 43 % for Δ φ = 90 °. Focusing is also observed to reduce the fluctuations in the wake velocity with the maximum reduction in fluctuations also corresponding to Δ φ = 90 °. Jet vectoring is able to deflect the von Kármán vortex street in a singular direction along with shifting of the front stagnation point with maximum deflection for Δ φ = 60 °. Furthermore, vectoring leads to an asymmetry in the wake velocity field with the shifting of the velocity deficit region in the direction of the vectoring along with an asymmetry in the wake velocity fluctuations. This novel approach toward synthetic jet induced active flow control allows for greater manipulation of the flow field characteristics of bluff bodies than present methods with applications in areas of underwater and micro air vehicle maneuvering, automobile, and building aerodynamics among others. [ABSTRACT FROM AUTHOR]

In this study, the transverse vortex-induced vibration (VIV) of an elastically mounted sphere with the application of a streamwise Lorentz force is investigated through direct numerical simulation. The research parameter range is 300 ≤ Re ≤ 1100 and − 0.8 ≤ N ≤ 1, where Re is the Reynolds number and N is the interaction parameter of the Lorentz force. The dependence of sphere responses, forces, and wake structures on Re and N is illustrated in detail. Within this range, two oscillation patterns are identified: VIV and desynchronization. Three wake patterns are identified: two-sided hairpin vortex emerges in the VIV region, while one-sided hairpin vortex and double-threaded wake structures are observed in the desynchronization region. The evolution of these wake patterns is related to the motion of the rear stagnation point (RSP) and separation line (SL) on the sphere surface. A large positive or negative Lorentz force suppresses the motion of RSP and SL, leading to the one-sided hairpin vortex or double-threaded wake structures replacing the two-sided hairpin vortex. Finally, the oscillation patterns are summarized on a map of amplitude response contours in the Re-N space. [ABSTRACT FROM AUTHOR]

The impact of the Thompson and Troian slip restrictions on continuous nanofluid flow, including CNTs near the stagnation point with constricting/enlarging surfaces, examined using a mathematical model. Engine oil is utilized as the base liquid, and both single-wall (SWCNTs) and multi-wall (MWCNTs) carbon nanotubes are taken into consideration. A Darcy-Forchheimer permeable medium and quartic autocatalysis, a chemical reaction for MHD stagnation point flow, are used to study the heat and flow characteristics of non-Newtonian flow. The original mathematical model is also expanded to include the impact of buoyancy forces. The numerical solution of non-dimensional velocity, temperature, and concentration profiles is obtained using the MATLAB-created bvp4c function, which employs the three-stage Lobatto IIIa formula. In the limited case, the validity of the recommended mathematical model is assessed by comparison with published work. A strong consensus is reached in this regard. Many dimensionless flow parameters, including the velocity slip parameter, the inertial coefficient, solid volume fraction, magnetic parameter, and the velocity parameter, have graphical representations that illustrate their behavior. Surface drag force estimates are presented to analyze the consequences on the extended surface. It has been demonstrated that increasing the slip velocity parameter boosts fluid flow speed while reducing surface drag. The efficiency of local thermal transmission decreases as the endothermic/exothermic coefficient rises. The altering viscosity factor for nanofluids causes an increase in axial velocity while a decrease in temperature distribution. Engine oil enriched with MWCNT and SWCNT can improve the thermal conductivity and viscosity of lubricants, leading to reduce wear and tear and better engine performance as well. Furthermore the incorporation of quartic autocatalytic reactions can enhance chemical processes that rely on catalysis, improving reaction rates. Also it has diverse applications in the system of cooling devices, manufacturing and material processing and heat transfer systems. It is revealed through this study that the system is shown to moderately cool off as measured by the solid volume ratio and heat generation. The velocity ratio parameter and the thermal expansion parameter had opposing outcomes on the system’s internal heat transfer mechanism.Article Highlights: As we increase the volume fraction of nanoparticles, the velocity of the fluid diminishes while temperature profile exhibits enlargement. Temperature of the fluid flow portrays the fall off pattern for the enhanced values of thermal relaxation time. An enhancement in the exothermic and endothermic factor shows lowering the concentration profile. [ABSTRACT FROM AUTHOR]

This study examines the generation of irreversibility and the behavior of stagnation point hybrid nanofluid flow on a Riga plate. The effects of nonlinear thermally convective and solar radiation are incorporated in the modeled equations. The nanoparticles of (Cu) and (Al2O3) are mixed with Glycol (C3H8O2) to hybridized it. The leading equations have been changed to dimension-free form by using the set of appropriate variables and then have been evaluated by Artificial Neural Network (ANN) approach. It is revealed in this work that, the velocity panels are amplified with expansion in Grashof number and electromagnetic factor while declined with escalation in magnet/electrode factor and nanoparticles concentration. Upsurge, in Eckert number for both the scenarios (Ec < 0) and (Ec > 0), the radiation factor and nanoparticles concentration cause augmentation in thermal characteristics. Radiation factor has positive impacts on Bejan number and generation of Entropy. Moreover, Bejan number is retarded while entropy is augmented with growth in Brinkman number. It is also established in this work that the principle of entropy generation for hybrid nanoparticles supports the efficient delivery of drug in cancer treatment. [ABSTRACT FROM AUTHOR]

Abstract The impact of the Thompson and Troian slip restrictions on continuous nanofluid flow, including CNTs near the stagnation point with constricting/enlarging surfaces, examined using a mathematical model. Engine oil is utilized as the base liquid, and both single-wall (SWCNTs) and multi-wall (MWCNTs) carbon nanotubes are taken into consideration. A Darcy-Forchheimer permeable medium and quartic autocatalysis, a chemical reaction for MHD stagnation point flow, are used to study the heat and flow characteristics of non-Newtonian flow. The original mathematical model is also expanded to include the impact of buoyancy forces. The numerical solution of non-dimensional velocity, temperature, and concentration profiles is obtained using the MATLAB-created bvp4c function, which employs the three-stage Lobatto IIIa formula. In the limited case, the validity of the recommended mathematical model is assessed by comparison with published work. A strong consensus is reached in this regard. Many dimensionless flow parameters, including the velocity slip parameter, the inertial coefficient, solid volume fraction, magnetic parameter, and the velocity parameter, have graphical representations that illustrate their behavior. Surface drag force estimates are presented to analyze the consequences on the extended surface. It has been demonstrated that increasing the slip velocity parameter boosts fluid flow speed while reducing surface drag. The efficiency of local thermal transmission decreases as the endothermic/exothermic coefficient rises. The altering viscosity factor for nanofluids causes an increase in axial velocity while a decrease in temperature distribution. Engine oil enriched with MWCNT and SWCNT can improve the thermal conductivity and viscosity of lubricants, leading to reduce wear and tear and better engine performance as well. Furthermore the incorporation of quartic autocatalytic reactions can enhance chemical processes that rely on catalysis, improving reaction rates. Also it has diverse applications in the system of cooling devices, manufacturing and material processing and heat transfer systems. It is revealed through this study that the system is shown to moderately cool off as measured by the solid volume ratio and heat generation. The velocity ratio parameter and the thermal expansion parameter had opposing outcomes on the system’s internal heat transfer mechanism.

There have been a lot of claims made in the literature recently regarding the physical characteristics of nanofluids in different flow systems, especially the laminar flow regimes. The goal of this study is to investigate the two‐dimensional laminar flow of Jeffrey liquid that describes the characteristics of heat and mass transfer towards a stagnation point over a radial moving disc through the Buongiorno nanofluid model. The study also aims to investigate the impact of mass transpiration velocity, magnetic field, and zero mass flux incorporated in a Jeffrey fluid. The study reduces complicated partial differential equations to a collection of ordinary differential equations using the similarity transformation, which makes it easier to compute dual numerical solutions using the bvp4c solver. A particular value of the shrinking parameter yields dual solutions. The findings of the current research demonstrate that the suction constraint amplifies the friction factor phenomenon in the second solution, while in the first solution, an annulment tendency is noted. Additionally, the first solution exhibits a monotonic behavior whereas the second solution shows a fall in both the friction factor and the rate of heat transfer by increasing the Deborah number. Finally, the results of this analysis with the available data matched the limiting situations very well. [ABSTRACT FROM AUTHOR]

Due to their widespread use in engineering, hybrid nanofluids have been the primary focus of mathematical and physical research. Only the improvement of hybrid nanofluids’ variable heat conductivity and viscosity has been considered so far. Hybrid nanofluid flow across an inclined cylinder has many potential uses, including heat transfer and cooling in electrical devices, energy storage, refrigerants, and the automobile industry. Examining the effects of buoyant force, variable viscosity, variable thermal conductivity, mass suction, convective thermal conditions, and a magnetic field on the stagnation point flow of a Al2O3–Cu/H2O hybrid nanofluid in an inclined cylinder is our objective in this work. In order to find solutions to boundary-condition flow-describing partial differential equations, we turn them into ordinary differential equations using similarity transformations. We achieve this by employing a numerical strategy known as the fourth-order Runge–Kutta technique, which incorporates shooting techniques. A graphical representation of the findings emphasizes the influence of many physical parameters on flow dynamics. In addition, we address the influence of drag force and rate of heat transfer on various elements, such as the Biot parameter, magnetic variable, viscosity variable, and thermal conductivity variable. The mixed convection and magnetic parameters cause the velocity profile to rise while the temperature profile falls. The research’s results elucidate the cause behind the rise in thermal contour of hybrid nanofluids, which is seen when there is an increment in thermal conductivity, radiation parameter, and Biot number. The heat transfer rate exhibits a significant increase of 36.87% in the aiding flow scenario when a 2.0 mass suction is applied in conjunction with a 0.01 hybrid nanofluid, as compared to the conventional fluid. In the scenario of opposing flow, the heat transfer rate exhibits a significant increase of 36.96% when compared to that of ordinary fluid. Heat transfer increases 43.00% when Rd increases from 0.1 to 0.5 for both assisting and opposing flow. [ABSTRACT FROM AUTHOR]

This study investigates the stable combustion range and CO/NO emissions of laminar premixed CH 4 -NH 3 impinging flames experimentally. Effects of flame impingement on the flame stability and CO/NO formations are analyzed quantitatively. The result shows that the flame impingement improves the flame stability considerably through decelerating the unburned gases velocity in the stagnation region, with smaller nozzle-to-wall distance (H) exerting stronger improvement on the flame stability. The NO emission is increased initially but dropped finally with the increased H. This trend is ascribed to the suppressed NO productions at both small and large H due to the intensive cooling effects of cold wall and ambient air entrainment respectively in consideration of the relatively inferior reactivity of NH 3. Additionally, due to the insufficient oxidizer in the fuel-rich flame, the more NH 3 molecule can also facilitate the NO destruction via the DeNOx pathways at small or large H. In contrast, the CO emissions show similar variation trends with H like the NO emission for the fuel-lean and stoichiometric flames, while the CO emission has a "N" type variation trend with H for the fuel-rich flames. Since the CH 4 reactivity can be improved by the NH 3 addition at low temperatures, a low-temperature environment at small H due to the strong cooling effect, as well as more available NH 3 in the flame, can effectively highlight the improvement of NH 3 on the CH 4 reactivity in the fuel-rich flame. This makes for the CO production at small H combined with the insufficient oxidizer and eventually results in the higher CO emission of the fuel-rich flame at small H. Additionally, the decreased CO emission at large H results from the improved CO oxidation that is caused by the increased residence time and more oxidizer from ambient air. • The laminar premixed CH 4 -NH 3 impinging flame is investigated experimentally. • The stability maps of the CH 4 -NH 3 free and impinging flames are obtained. • The CH 4 -NH 3 impinging flame has the better stability in a wider range of conditions. • NO emissions are influenced considerably by the cooling effects of wall and air. • The NH 3 addition increases the CO emissions of fuel-rich flames at small H. [ABSTRACT FROM AUTHOR]

In the existing investigation, impacts of slip and chemical reactions on mass and heat exchange on an incompressible and electrically conducting micropolar fluid past a porous wedge within the sight of Hall and ion slip are examined. By employing similarity conversion, the relevant highly nonlinear PDEs are reformed into a collection of nonlinear linked ODEs. The equations framed in this manner have been resolved by using the bvp5c, the in-build MATLAB. Examination of magneto-hydrodynamic micropolar fluid on stagnation point flow is significant due to its uses in the production of plastic substances, polymer extrusion, lubricants, etc. The influence of the magnetic field, heat generation, microrotation, along with Hall and ion slip on the liquid flow is analyzed. Examination with prior published research papers is performed and the outcomes are compared with each other. Numerical simulations for shear stress coefficients, Sherwood and Nusselt numbers are provided in tabular form, and in addition, the variations in axial and microrotation velocities, temperature and solutal profiles are evaluated visually for various parameters in detail. The ion slip and slip velocity both slow down the shear rate, whereas the elevated values of the Hall and magnetic parameters show an opposite trend. The profile shows thinning of the bounding surface and offers its greatest magnitude in the case of a Newtonian liquid. [ABSTRACT FROM AUTHOR]

Flow around a solid sphere finds utility in numerous single- and two-phase engineering applications, such as sport balls, combustion systems, silt conveyance in waterways, hydraulic conveying, pneumatic equipment, food and chemical manufacturing. Therefore, this paper aims to examine the Casson nanofluids flow and heat transfer over a solid sphere that is saturated in an isotropic porous material in the presence of Stefan blowing and slip conditions. The forced situation is due to the presence of a stagnation point while the surface of the sphere is subjected to thermal slip conditions. Besides, various significant impacts are taken into account such as Lorentz force, thermal radiation, heat source/sink, and activation energy. The solution technique is based on non-similar transformations and implicit finite difference method with the Blottner algorithm. It is remarkable that, for all values of the activation parameter, the growth of Stefan number reduces the gradients of the velocity, temperature, and nanoparticle concentration. Also, the presence of the thermal slip factor reduces the temperature distributions. Additionaly, an increase in either the Casson parameter or Darcy number enhances the flow while both temperature and concentration are diminishing. Furthermore, there is an improvement in values of the Nusselt number up to 50.57 % when the magnetic parameter is varied from 0 to 6. [ABSTRACT FROM AUTHOR]

Recently, researchers are facing great challenges to form the homogeneous solutions of various liquids at biomedical and industrial levels. Such homogeneous solutions can be controlled through stratification phenomenon directly which is ignored by the researchers in the existing literature specifically quadratic stratification and melting heat mechanism which is valid only for higher temperature processes. Thus, to form the homogeneous and stable liquid solutions for various industrial processes, we investigate the melting heat phenomenon in quadratic stratified Jeffery Nano fluid flow deformed due to linearly stretching sheet along with stagnation point. Inclined constant magnetic field is implemented on the fluid through an arbitrary angel. Characteristics of heat and transportations are disclosed through viscous dissipation, Brownian motion and thermphoresis. Temperature and concentration of the surrounding fluids are assumed higher than the stretching surface. The resultant governing equations are reduced to ordinary differential equations through proper transformations. Convergent analytical series solutions are computed via homotopic approach. Impact of various emerging parameters on temperature, velocity and concentration fields are illustrated and discussed comprehensively. Sherwood and Nusselt numbers and drag force are scrutinized mathematically, physically and graphically. It is analyzed from the study that (i) dominant melting reduces the temperature field (ii) higher thermal and solutal stratification decay the temperature and concentration fields respectively (iii) higher thermophoresis enhances the temperature field. Further, it is concluded that stable and homogeneous solutions may be made by increasing melting and reducing stratification phenomena. This study will help us to provide actual amount of heat for heating processes in industries and biomedicine which is the basic requirement for excellent quality of products. [ABSTRACT FROM AUTHOR]

Steep wave breaking on a vertical cylinder (a typical foundation supporting offshore wind turbines) will induce slam loads. Many questions on the important violent wave loading and the associated secondary load cycle remain unanswered. We use laboratory experiments with unidirectional waves to investigate the fluid loading on vertical cylinders. We use a novel three-phase decomposition approach that allows us to separate different types of nonlinearity. Our findings reveal the existence of an additional quasi-impulsive loading component that is associated with the secondary load cycle and occurs in the backwards direction against that of the incoming waves. This quasi-impulsive force occurs at the end of the secondary load cycle and close to the passage of the downward zero-crossing point of the undisturbed wave. Wavelet analysis showed that the impulsive force exhibits superficially similar behaviour to a typical wave-slamming event but in the reverse direction. To monitor the scattered wave field and extract run-up on the cylinder, we installed a four-camera synchronised video system and found a strong temporal correlation between the arrival time of the Type-II scattered wave onto the cylinder and the occurrence of this quasi-impulsive force. The temporal characteristics of this quasi-impulsive force can be approximated by the Goda wave impact model, taking the collision of the Type-II scattered waves at the rear stagnation point as the impact source. [ABSTRACT FROM AUTHOR]

THE STAGNATION POINT FLOW OF AN INCOMPRESSIBLE VISCOUS electrically conducting fluid impacting orthogonally on a heated rotating disk is studied with internal volumetric heat generation/absorption in the presence of a uniform magnetic field. A uniform suction or injection is applied through the surface of the disk. Appropriate similarity transformations are used to reduce the governing differential equations of the problem into a system of nonlinear ordinary differential equations and then solved numerically using the fourth-order Runge-Kutta method. In the second step, the work is oriented towards linear stability analysis by considering infinitesimally small disturbances within the boundary layer. Using normal mode decomposition in the Görtler-Hammerlin framework, the resulting eigenvalue problem is then solved numerically by means of the pseudo-spectral method using Laguerre's polynomials. As a result, the critical conditions for the onset of thermal instability are described and discussed in detail using multiple configurations. It is found that the presence of a magnetic field and suction/injection act to increase the stability of the basic flow. However, the rotation parameter and the internal heat generation/absorption contribute significantly to destabilizing the basic flow. [ABSTRACT FROM AUTHOR]

This study experimentally determines high-frequency aeroacoustic noises of the high-speed dual-impinging jet, focusing on the generation and evolution mechanism between impingement tones modes and far-field acoustic spectra. The variables of the high-speed impinging jet are Mach number (Ma = 0.9 and 1.1), fixed diameter (D) of nozzle, nozzle spacing (3.5D), and impingement distance (4D). A novel fast-responding pressure-sensitive paint (fast-PSP) with a significantly extended frequency response ability was designed to develop an accurate phase-resolving propagation process of aeroacoustic noises and handle high impingement momentum challenges posed by the high-speed impinging jet. The PSP raw data were enhanced by calibration, image restoration, and proper orthogonal decomposition filtering. Two distinct far-field spectral characteristics were identified based on synchronized acoustic measurements. The existence of the stagnation region affected by the fountain effect in the dual-impinging jet was determined using spatial–temporal cross-correlation analysis. Subsequently, the concurrent axisymmetric dual annulus mode and its coupling behavior at Ma = 0.9 and the non-axisymmetric helical mode and its periodic fragmentation-reconstruction patterns at Ma = 1.1 were identified by spectral proper orthogonal decomposition. Finally, the spatial–temporal evolution of the phase-locked first-order mode was extracted, and the transient variations of coherent structures and their mechanisms for discrete tone noise generation were quantitatively investigated. The expansion and coupling of the dual annulus modes promoted the dominance of single-tone peaks across the entire acoustic spectrum. The helical mode, exhibiting both rotational and expansion behaviors, enhanced the coherent vorticity at the periphery of the coherent structures, resulting in intense impingement tones sound sources. [ABSTRACT FROM AUTHOR]

The objective of this research endeavor is to examine the properties of stagnation point flow in the presence of absorption, viscous dissipation, and internal thermal generation with respect to a shrinking surface. The resulting system of differential equations is notoriously challenging to solve analytically. The equations controlling the boundary layer flow were solved using a finite difference method. The analysis includes the examination of important physical quantities through the presentation of plots and tabulated values. Our findings reveal a strong connection between the presence of solutions for high shrinking parameters and the magnetic field that was applied. Temperatures increase when there is an increase in both Ec and α at the same time. These results also suggest a shallowing of the thermal boundary layer. As a result of these findings, it appears that temperature and thermal boundary layer thickness are sensitive to changes in these factors. [ABSTRACT FROM AUTHOR]

The flow in the gap between an inner and outer cylinder presents a variety of regimes, which are well explored. In the present work, we attempt to explore a more complex flow, with two parallel co-rotating inner cylinders. The rationale behind this arrangement was the following: in terms of base two-dimensional flow, close to each inner cylinder, the base flow resembles a laminar Couette flow, and close to the outer cylinder, the flow may again resemble a Couette flow, with the two inner cylinders being seen as a single source of momentum, while in the middle point between the inner cylinder, there is stagnation saddle point with two incoming and two out coming streamlines, creating a zone with a high shear where interaction of Taylor–Couette style rolls is expected. The experiment allowed to identify six regimes: for R e < 50 , presence of the base two-dimensional flow; for 50 < R e < 70 , the first regime of steady rolls, equivalent to Taylor vortices; for 70 < R e < 110 , vortices become unsteady; for 110 < R e < 170 , in the stretched zone, the flow is unsteady while the same fluid parcels are then stabilized when leaving the stagnation point region and slowed down toward the outer wall; when R e > 170 , there is the onset of turbulent rolls, with loss of spatial periodicity and apparition of turbulence; and finally a second type of steady rolls occurs for a sudden start of cylinders and 50 < R e < 60. [ABSTRACT FROM AUTHOR]

Flow around square cylinders has been studied via unsteady simulations done at a Reynolds number of Re = 100. In the present study, the effects of rounded corners on different flow characteristics have been evaluated. The main influence of rounded corners has been considered for various ratios (r*) up to 0.45 in terms of drag coefficient values. Flow stagnation points have been obtained in front of the square cylinders. These points constitute the maximum pressure. The cluster sizes for cross-stream velocity components are nearly the same. Viscous flow generates vortices around the top and bottom edges of the square cylinder. The produced vortices have been affected by the wake region. When moving away from the bodies, streamwise velocity profiles have been influenced by the variation of the rounded corner ratios. The wake region has shrunk owing to the rounded corners, and the drag reduction has been provided. The drag coefficient (CD) has been obtained as 1.418 for r* = 0. As a result of increasing the ratio for the rounded corners, drag coefficients decreased for the square cylinders. The percentage values are 4.6%, 7.2%, 8.4%, 9.6%, 11.1%, 11.9%, 12.5%, 13.3%, and 14.3% for the drag decrement from r* = 0.05 to r* = 0.45 when compared to the reference value. The most effective value for drag reduction has been attained as 4.6% for the ratio of rounded corners in a row. Even though the decrement percentage tends to increase by enhancing the ratio of the rounded corners, the increment rate indicates the decreasing trend. [ABSTRACT FROM AUTHOR]

Aircraft icing seriously threatens flight safety. This paper describes a modified shallow-water icing thermodynamic model that is applicable to unstructured grids and considers the effects of changes in water physical parameters and sublimation on icing. An icing calculation method enables the automatic determination of whether freezing occurs and the type of icing. An autonomous icing calculation program is developed to extract the geometric coordinates and mesh information of the icing surface and combine this information with the multiphase flow field of air-supercooled water droplets. The icing equations in the Godnov format are discretized to produce a large-scale sparse matrix that is solved iteratively using the biconjugate gradient stabilized method. The output includes parameter distributions for the ice thickness, water film thickness, and equilibrium temperature. Taking the National Advisory Committee for Aeronautic 0012 airfoil as the study object, the results of icing simulations are compared with experimental data from an ice wind tunnel and the ice shapes calculated by the FENSAP-ICE software. The results are found to be in good agreement with the experimental data, and the ice height errors at stagnation points are less than 15%. In the case of rime ice, single-horned ice shapes are simulated for both conventional and large supercooled droplets. For mixed ice and glaze ice, double-horned ice shapes are simulated for both droplet conditions. FENSAP-ICE fails to simulate the ice horns and produces large errors in ice thickness and ice range. [ABSTRACT FROM AUTHOR]

Oblique stagnation flow on a rotating disk is commonly observed in processes such as spinning coating and thin film deposition techniques. The investigation of the unsteady oblique stagnation point flow for Maxwell fluid over an oscillating-rotating disk embedded in a porous medium is meticulously conducted by employing the Darcy–Maxwell framework in conjunction with Cattaneo–Christov double diffusion model. A transformation of similarity is applied to reframe the governing equations into a system of non-dimensional coupled partial differential equations, whose numerical solutions are secured by the Chebyshev Spectral Newton Iterative Scheme. The outcomes underscore that an escalation in the Darcy parameter escalates the resistance within the porous medium, consequently leading to a reduction in velocity. Both the first-order slip and the second-order slip mitigate the fluid's interaction with the disk wall, leading to a retardation in flow velocity. Additionally, the presence of augmented thermal radiation parameters is observed to enhance heat transfer efficiency, resulting in a more homogenized temperature distribution. The two-dimensional and three-dimensional streamlines provide a precise depiction of the flow characteristics at the oblique stagnation point on the oscillating-rotating disk. These findings offer a theoretical foundation that can be instrumental for forthcoming research in analogous fields. [ABSTRACT FROM AUTHOR]

The jet impingement cooling technique is regarded as one of the most effective enhanced heat transfer techniques with a single-phase medium. However, in order to facilitate manufacturing, impingement with a large number of smooth circular hole jets is used in engineering. With the increasing maturity of additive technology, some new special-shaped holes (SSHs) may be used to further improve the cooling efficiency of jet impingement. Secondly, the heat transfer coefficient of the whole jet varies greatly on the impact target surface. The experiments with a large number of single smooth circular hole jets show that the heat transfer coefficient of the impact target surface will form a bell distribution—that is, the Nusselt number has a maximum value near the stagnation region, and then rapidly decreases exponentially in the radial direction away from the stagnation region. The overall surface temperature distribution is very uneven, and the target surface will form an array of cold spots, resulting in a high level of thermal stress, which will greatly weaken the structural strength and life of the equipment. Establishing how to ensure the uniformity of jet impingement cooling has become a new problem to be solved. In order to achieve uniform cooling, special-shaped holes that generate a swirling flow may be a solution. This paper presents a summary of the effects of holes with different geometrical features on the flow field and heat transfer characteristics of jet impingement cooling. In addition, the effect of jet impingement cooling with SSHs in different array methods is compared. The current challenges of jet impingement cooling technology with SSHs are discussed, as well as the prospects for possible future advances. [ABSTRACT FROM AUTHOR]

Heat absorption and thermal radiation have significant roles in engineering and research. These two principles have applications in thermal transportation, gas turbines, nuclear power plants, electrical fuel, aerospace engineering, projectiles and renewable energy. The present work analyses the stagnation point ternary nanofluid motion over a circulating sphere in the presence of a magnetic field and radiation absorption. The nonlinear controlling equations are replaced by ordinary differential equations by applying a suitable comparison factor. The bvp4c process was used to establish numerical outcomes of the partial differential equations. This mathematical numerical findings are presented graphically. The results of ternary nanoparticles (Cu–Ag–CuO/water), hybrid nanoparticles (Cu–Ag/water) and copper (Cu) nanoparticles have also been compared, and this comparison suggests that ternary nanoparticles (Cu–Ag–CuO/water) are more effective at attenuating hemodynamic factors (such as wall shear stress and heat transfer) than hybrid and copper (Cu) nanoparticles. Comparison with previous literature results is also done and the results are found to be in very good agreement with those published earlier. [ABSTRACT FROM AUTHOR]

This research aims to examine the impact of viscous dissipation, slip conditions, and radiation on the stagnation point flow when a stretching/shrinking sheet is immersed in a Maxwell fluid. The significance of viscous dissipation has great importance in an extensive range of engineering applications, including heat exchangers, lubrication systems, polymer processing, and biofluid mechanics. In heat and mass transfer fluid flow problems, viscous dissipation can have significant effects, particularly in situations involving high fluid velocities or high viscosity fluids. In this computational study, the governing equations, namely the momentum, and energy equations, are formulated and non-dimensionalized using appropriate similarity parameters and the Runge-Kutta-Fehlberg method is then employed to resolve the problem. The obtained results provide detailed insights into the velocity, temperature, skin friction and wall temperature distributions in the flow domain. Additionally, the role of viscous dissipation in altering the heat transfer characteristics of the Maxwell fluid is examined. The results indicate that the existence of viscous dissipation significantly impacts the flow behaviour of the Maxwell fluid. It alters the boundary layer thickness, temperature distribution, and the overall heat transfer rate. Additionally, it is observed that the values of the Prandtl number strongly affect the influence of viscous dissipation on the velocity and temperature distribution. The outcomes of this study correlate with those that have been previously reported. [ABSTRACT FROM AUTHOR]

In the present research, the stagnation point flow of EMHD Casson nanofluids over a stretchable electromagnetic plate is considered. Flow over the Riga plate is considered to analyze the Electromagnetic influences on fluid flow. Also, permeability, radiation, chemical reaction and heat source attributes are considered in this study. The guiding equations of the problem are transformed to nonlinear ODE using suitable similarity transformations. The numerical investigation of the flow is studied by implementing the Keller Box procedure using MATLAB. Validation of the numerical method is analyzed by comparing it with the previous studies. Also, calculated numerical observations of the local Nusselt and Sherwood parameters are of interest. An increase in the velocity outlines is detected for augmented observations of modified Hartmann number and unlike trends are noted for Casson, permeability, Prandtl number and suction factors. Temperature enhancement is witnessed for radiation, heat source, thermophoresis, Brownian diffusion and Biot number cases. Opposite trends are perceived in the case of suction constant. Concentration profiles are increasing for the alterations of thermophoresis parameter and declined in case of radiation, heat source, Brownian diffusion and Lewis number. [ABSTRACT FROM AUTHOR]

The present work is focused on the stagnation point flow over a Jeffery fluid flow through a stretching/shrinking sheet. The nanoparticles namely Cu are considered by exploiting water-based fluid. The governing nonlinear system of partial differential equations is converted into a system of highly nonlinear ordinary differential equations via a similarity transformation. Therefore, it is quite significant to assimilate the analytical extension of heat transfer and mass transfer fluid in the presence of porous under the influence of slip velocity. The analytical solution available for nondimensional momentum, heat transfer, and concentration profiles across the boundary layer is examination is done by checking the various values of physical parameters viz., Prandtl number, Radiation parameter, stretching/shrinking parameter, and mass transpiration for the flow and heat transfer which are obtainable through graphs. The present work on nanofluids flowing through stretching/shrinking surfaces has numerous applications in biomedicine, solar energy, cooling, nuclear system cooling, etc. [ABSTRACT FROM AUTHOR]

Using data from the regional broadband dense temporary array deployed by the ChinArray project, we applied the three-dimensional (3D) Kirchhoff migration method of the teleseismic P-wave receiver function to investigate discontinuity structures of the mantle transition zone (MTZ) in the central and western parts of the North China Craton (NCC) using a high-resolution 3D velocity model of the East Asian region. The results show that the 410-km discontinuity beneath the Datong Volcano is depressed by ∼10 km, indicating the presence of a high-temperature anomaly near the depth of 410 km, which is likely related to small-scale mantle upwelling caused by the dehydration of the stagnant Pacific Plate in the MTZ. The upwelling of hot material provides a heat source for surface magmatic activity. Beneath the Bohai Bay Basin, significant subsidence of the 660-km discontinuity is observed, and the transition zone here is extensively thickened. It's suggested that the anomalies in this region are related to the stagnation of the Pacific slab in the MTZ. Although the thickness of the transition zone west of the North-South Gravity Lineament appears normal, we propose that the subducting front of the Pacific slab did not cross the gravity lineament in the NCC. In comparison, the small-scale subsidence of the 660-km discontinuity and the thickening of the MTZ observed north of the Hannuoba Volcano likely indicate that the slab crossed the gravity lineament at its turning point and remained in the MTZ. Furthermore, a local thickening of the MTZ is observed in the Dabie orogenic belt of the Qinling Mountains. This is believed to be a combined effect of lithospheric delamination into the transition zone in the lower Yangtze region and the stagnation of the Pacific Plate. [ABSTRACT FROM AUTHOR]

This study examines the effect of heat production and radiation absorption on the magnetohydrodynamic Casson fluid flow at the stagnation point in a porous medium. We convert the group of fluid flow equations, which are non-linear partial differential equations with suitable boundary constraints, into a set of non-linear ordinary differential equations using similarity transformations. The homotopy analysis method (HAM) solves the converted system of ordinary differential equations. We draw graphs for numerous values of non-dimensional parameters and tables of surface drag force, rates of heat transfer, and mass transfer to analyze the relationship between velocity field, temperature field, concentration field, and other essential parameters involved in the study. We have proven that the Dufour number, radiation parameter, and heat generation parameter elevate the fluid temperature, whereas the magnetic parameter lowers it. The Casson fluid parameter, buoyancy force parameter, and mixed convection parameter all promote fluid movement throughout the flow field. The presented tabular data allows us to see the trend of heat and mass transfer rates, as well as drag force rates, against important parameters, enhancing our understanding of these rates. [ABSTRACT FROM AUTHOR]