Magnetic Angle Research Articles

Convection flow of NE-phase change material-water mixture in evacuated tube solar collector manifold: Numerical analysis of MHD double-diffusive convection and exothermic reaction

This study investigates the convection flow of nano-encapsulated phase change material (NEPCM)-water mixture in an evacuated tube solar collector manifold, focusing on the effects of magnetohydrodynamic (MHD) double-diffusive convection and exothermic reaction. Computational fluid dynamics simulations using the Galerkin finite element method were employed to analyze temperature and concentration distributions, fluid flow, melting zone of PCM nanocapsules, Nusselt number, Sherwood number, entropy generation, and thermal performance. The numerical analysis considers a range of dimensionless parameters, including Rayleigh number (Ra=103−105), Lewis number (Le=0.1−10), buoyancy ratio (Nz=1−5), nanoparticle concentration (ϕ=0.01−0.035), fusion temperature (ϴf=0.1−0.9), Stefan number (Ste=0.1−0.9), Hartmann number (Ha=0−50), magnetic field inclination angle (γ=0°−90°), and Frank-Kamenetskii number (FK=0−2.5). Results show that increasing Ra enhances the average Nusselt number (Nuav) by up to 156.1 % and the average Sherwood number (Shav) by up to 104.5 %, while increasing the total entropy generation by up to 13,155 %. Increasing FK reduces Nuav by up to 42.2 % but increases Shav by up to 13.1 %. The Lewis number and buoyancy ratio significantly influence the hydrothermal performance, with Nuav exhibiting non-monotonic behavior and Shav increasing by up to 240.9 % as Le increases. The nanoparticle concentration enhances Nuav by up to 49.7 %. Interestingly, the magnetic field effects are less pronounced than in previous studies, with Ha having a minor impact on Nuav and Shav. These findings have significant implications for the design and optimization of evacuated tube solar collectors and other thermal energy storage systems, potentially leading to improved efficiency and performance in real-world applications.

Research on Performance of Interior Permanent Magnet Synchronous Motor with Fractional Slot Concentrated Winding for Electric Vehicles Applications

The fractional-slot, concentrated-winding, interior permanent magnet synchronous motor (FSCW IPMSM) has advantages, such as reducing motor copper consumption, improving flux-weakening capability, and motor fault tolerance, and has certain development potential in application fields such as electric vehicles. However, fractional-slot concentrated-winding motors often contain rich harmonic components due to their winding characteristics, leading to increased motor losses and back electromotive force harmonics, thereby affecting the efficiency and constant power speed regulation range of the motor. Based on this, this article first uses the winding function method to explore the inductance and saliency ratio of the interior permanent magnet synchronous motor with different slot pole combinations in the fractional-slot concentrated- winding of electric vehicles. Secondly, this article will establish a 2D finite element parameterized model to analyze and compare the performance of fractional-slot concentrated-winding motors with different slot pole combinations, including air gap magnetic density, back electromotive force distortion rate, overload multiple, and torque. The structural parameters of the motor were optimized with the objective of minimizing the torque ripple under the constraint of minimizing the average torque reduction. The motor slot width, permanent magnet angle, and permanent magnet pole arc angle were analyzed and optimized. The simulation results showed that 12 slots and 8 poles were the optimal design schemes, providing a theoretical basis for the selection of slot pole coordination in the fractional-slot concentrated-winding interior permanent magnet synchronous motor for electric vehicles.

Magnetic field effects on double-diffusive mixed convection and entropy generation in a cam-shaped enclosure

This study investigates double-diffusive mixed convection and entropy generation under magnetic influence within a novel cam-shaped enclosure, with applications in automotive engineering. The unique geometry creates distinct flow patterns that enhance heat and mass transport. Using the Galerkin finite element method, we analyzed the effects of key parameters, including buoyancy ratio, Reynolds number, Hartmann number, magnetic field inclination angle on average Nusselt and Sherwood numbers, and total entropy generation. Results show that increasing the buoyancy ratio and Reynolds number enhances heat transfer, while the Hartmann number significantly impacts flow characteristics and entropy generation. The magnetic field inclination angle exhibits a non-linear effect on heat transfer and entropy production. These findings provide valuable insights for optimizing heat transfer systems in complex automotive geometries.

Dual-channel asymmetric absorption-transmission properties based on plasma metastructures-photonic crystals

In this paper, a kind of plasma metastructures-photonic crystals (PMPC) structure is proposed to investigate the absorption and transmission properties of electromagnetic waves (EWs) incident from opposite directions. The results show that the PMPC can achieve a dual-channel asymmetric absorption-transmission (AAT) phenomenon. At an operating bandwidth (OB) of 2.15∼2.85 GHz, EWs are absorbed in the forward incidence and transmitted in the backward case, and a relative bandwidth (RB) with forward absorption above 0.9 is 28.0%. On the contrary, at an OB of 7.07∼7.67 GHz, EWs can be transmitted in the forward propagation and absorbed in the backward case with a RB of 8.1%. Moreover, the effects of parameters such as applied magnetic field, incident angle, and tilt angle on AAT performance are investigated separately. The proposed dual-channel tunable AAT will further extend the application of asymmetric devices in the fields of optical communication and optical transmission.

Implementation of stacking regressor model on the flow induced by TiO2‐H2O and Ti6Al4V‐H2O nanofluid with waste discharge concentration

AbstractThe present investigation examines the circulation of and based nanofluids while considering the concentration of waste discharge. An innovative stacking regressor model is used to increase prediction accuracy. Using Shooting and Runge Kutta Fehlberg's fourth and fifth‐order schemes, the governing equations are converted into ordinary differential equations using similarity transformation and then numerically solved. The findings are represented graphically, and the model's correctness is assessed using Gaussian Process Regression, Categorical Boost, Extreme Gradient Boosting, and Random Forest, with linear regression acting as a meta‐model. The closely related testing and training data show the model's consistency and stability. Magnetic field and inclination angle will decline the velocity, space, and temperature‐dependent internal heat generation factors will enhance the temperature. Raising the pollutant external source parameter raises concentration. In all the cases, shows better performance than based nanofluid. The work's application ranges from fluid dynamics to waste management. By offering precise forecasts of nanofluid concentration, the proposed prediction model may aid in designing and optimizing waste discharge systems.

A two-step self consistent algorithm for extracting magnetic anisotropy constants from angle-dependent ferromagnetic resonance measurements

To infer anisotropy parameters of magnetic materials from experimental measurements of ferromagnetic resonance (FMR) (with data comprising resonant frequencies and corresponding resonant magnetic fields), a fitting procedure to the theoretical model is essential. The governing equation for this fitting process is the Smit–Beljers equation (SB equation), which links FMR frequencies to resonant magnetic field values and anisotropy parameters nonlinearly, and through the equilibrium magnetization angle values, which also depend on the same anisotropy parameters and magnetic field values. Obtaining an analytical expression for this equation is rarely possible. In this paper, we address the challenges posed by the Smit–Beljers equation and propose a two-step self-consistent algorithm to extract the relevant parameters efficiently.

Determining the Interstellar Wind Longitudinal Inflow Evolution Using Pickup Ions in the Helium Focusing Cone

The size, shape, and composition of the heliosphere are affected by its interaction with the local interstellar medium. A means of quantifying this interaction is by measuring the relative motion of the two media. We determine the flow direction, λISN , of the interstellar wind through the heliosphere and its trend over an 11 yr solar cycle using Advanced Composition Explorer/Solar Wind Ion Composition Spectrometer He+ double-coincidence pickup ion (PUI) measurements from a data set spanning 13 full orbits, with focusing cone crossings occurring between the years 1998 and 2010. We measure the flow direction by fitting a kappa function to the focusing cone signature in the count rates of He+ at the PUI cutoff measured as a function of ecliptic longitude. We determine λISN for each three-orbit boxcar centered on the years 1999 through 2009 and find the trend of the resulting linear fit. We account for solar transients by removing measurements associated with CMEs. However, there still may be effects from compression regions, such as stream–stream and corotating interaction regions. We additionally make considerations to ensure the PUI torus is in view, to account for varying interplanetary magnetic field angles, to ensure that we analyze newly injected interstellar PUIs largely unaffected by transport effects, and to account for general solar activity. We measure a slope in the flow direction to be 0.00° ± 0.51°​​​​ yr−1, indicating that we do not measure a varying trend over this period. We repeat the focusing cone analysis for the combined data set and determine an overall flow direction of 75.37° ± 0.43°.

The Independence of Magnetic Turbulent Power Spectra to the Presence of Switchbacks in the Inner Heliosphere

An outstanding gap in our knowledge of the solar wind is the relationship between switchbacks and solar wind turbulence. Switchbacks are large fluctuations, even reversals, of the background magnetic field embedded in the solar wind flow. It has been proposed that switchbacks may form as a product of turbulence and decay via coupling with the turbulent cascade. In this work, we examine how properties of solar wind magnetic field turbulence vary in the presence or absence of switchbacks. Specifically, we use in situ particle and fields measurements from Parker Solar Probe to measure magnetic field turbulent wave power, separately in the inertial and kinetic ranges, as a function of switchback magnetic deflection angle. We demonstrate that the angle between the background magnetic field and the solar wind velocity in the spacecraft frame (θ vB ) strongly determines whether Parker Solar Probe samples wave power parallel or perpendicular to the background magnetic field. Further, we show that θ vB is strongly modulated by the switchback magnetic deflection angle. In this analysis, we demonstrate that switchback deflection angle does not correspond to any significant increase in wave power in either the inertial range or at kinetic scales. This result implies that switchbacks do not strongly couple to the turbulent cascade in the inertial or kinetic ranges via turbulent wave–particle interactions. Therefore, we do not expect switchbacks to contribute significantly to solar wind heating through this type of energy conversion pathway although contributions via other mechanisms, such as magnetic reconnection, may still be significant.

Numerical analysis of unsteady free convection of Al2O3 inside a tubular reactor under the influences of exothermic reaction, and inclined MHD as an application to chemical reactor

This paper delves into the numerical investigation of aluminum oxide–water nanofluid thermal and dynamic performances under the influences of magnetic field application and chemical reaction, utilizing the Finite Element Method within a circular enclosure containing three inner tubes, as an application to the heat exchanging phenomenon between the reactive shell of the cavity and the surface of the triple tubes. Various governing parameters were studied for their interaction on the nanofluid flow and heat transmission rate within the proposed geometry, including the Rayleigh parameter (103≤Ra≤105), Hartmann parameter (0≤Ha≤61), nanoparticles concentration (0≤∅≤6×10-2), magnetic rotational angle (0o≤γ≤90o), and Frank-Kamenetskii parameter (0≤Fk≤3). The results indicated that raising Ra from 103 to 105 results in expediting the nanofluid velocity by 10.62 % and 100 % respectively as well as raising the total heat transfer efficiency. The nanofluid speed was also increased by 28.57 % when Fk has to further increase to a value of 3. When there was no exothermic activity present, the rate of heat transmission was at its lowest, and it was greater when the Fk value was 3. Similarly, there were discernible impacts in various areas of the geometry as the Ha number intensified and the Nuavg decreased. Improvements in local and mean Nusselt parameters are observed when the concentration of nanoparticles is increased, suggesting better heat transfer, achieving an increase by 7 % in the average Nusselt number. This research emphasizes the importance of nanoparticle concentration in raising the medium’s rates of heat transmission, contributing to advancements in energy storage development.

Self-consistent modelling of radio frequency sheath in 3D with realistic ICRF antennas

Abstract Ion Cyclotron Resonant Frequency (ICRF) induced impurity production has raised many concerns since ITER proposed to change the first wall material from beryllium to tungsten. Enhanced DC plasma potential (VDC) due to RF sheath rectification is well known as one of the most important mechanisms behind the RF induced impurities. Our previous work (L. Lu et.al, Plasma Phys. Control. Fusion 60 (2018) 035003) considered the impact of both the slow wave and the fast wave on the RF sheath rectification in a 2D geometry. It can barely recover the double-hump structure of the VDC poloidal distribution observed in various machines when only the slow wave is modelled using the multi-2D approach which intrinsically assumes the poloidal wavenumber kz is zero. The fast wave on the other hand is found to be more sensitive to a finite kz and may need to be tackled in 3D. This work reports our recent progress on the 3D RF sheath modelling. In this new code, the latest RF sheath boundary conditions (J. R. Myra, J. Plasma Phys. 87 (2021) 905870504) and the realistic 3D ICRF antennas are implemented. Compared to the 2D results, the 3D code could well recover the double-hump poloidal distribution of VDC even with the fast wave included, which confirms our speculation on the necessity of treating the fast wave in 3D. While the double-hump pattern is robust in the simulation, the amplitude of VDC is found to be affected by the magnetic tilt angle and the antenna geometry. This emphasizes the importance of adopting a realistic antenna geometry in the RF sheath modelling. The double-hump VDC poloidal structure breaks as the magnetic tilt angle increases. This is explained by the gyrotropic property of the cold plasma dielectric tensor. The spatial proximity effect we identified in the previous 2D simulations is still valid in 3D. Finally, simulation shows the slow wave dominates the RF sheath excitation in the private SOL, while the fast wave gradually takes over when moving to the far SOL region. This code could be a new tool to provide numerical support for ITER impurity assessment and ICRF antenna design.

Effects of nucleon-nucleon short-range correlation and symmetry energy on the evolution of newly born magnetars

Abstract Millisecond magnetars are widely suggested as the central engines powering hydrogen-poor superluminous supernovae (SLSNe). These magnetars primarily lose huge rotational energy through gravitational wave radiation (GWR) and magnetic dipole radiation (MDR), with MDR serving as an energy source for SLSNe. We study the evolution of the magnetar spin, magnetic inclination angle, and the resulting thermal radiative luminosity of the SLSNe, where the impacts of the nucleon-nucleon short-range correlation, the mass and initial spin of the magnetar, and the density-dependent symmetry energy of the dense nuclear matter on the evolution are discussed. The relativistic mean-field theory is employed to calculate the nuclear matter properties, and we particularly concentrate on the time- and space-dependent bulk viscosity which is crucial for the magnetic inclination angle evolution. It is found that the nucleon-nucleon short-range correlation weakens the damping of bulk viscosity of dense matter and therefore inhibits the growth of magnetic inclination angle, and it reduces the MDR (GWR) peak luminosity of a canonical magnetar by several times while it raises the peak thermal radiation luminosity of SLSNe by several times. For magnetars with nonrotating mass obviously lower than the $1.4 \, \rm M_\odot$ with slow initial rotation, the magnetic inclination angle is more likely to evolve towards 0 degrees quickly, and these magnetars are not suitable as the central engine for SLSNe. Within the ‘family’ of FSUGarnet interaction, a stiffer symmetry energy gives a lower threshold of direct Urca process and hence gives a much larger bulk viscosity coefficient, and thus it promotes the growth of the magnetic inclination angle and the GWR for canonical stars but reduces the peak brightness of SLSNe significantly.

Magnetic elastomer composites with tunable magnetization behaviors for flexible magnetic transducers

AbstractMagnetic elastomer composites are extending the field of soft robotics by integrating the flexibility of elastomers with the versatile performance of magnetic materials. In this work, a series of magnetic elastomers (BaCoxTixFe12–2xO19/PDMS) with tunable magnetic response have been successfully synthesized. In this composite, the magnetic component consists of Co‐Ti co‐doped barium hexaferrite (BaCoxTixFe12–2xO19, BCTF) nano powders, and the matrix is made of polydimethylsiloxane (PDMS). The coercivity (Hc) of BCTF can be reduced from 3950 Oe to 70 Oe, which bestow on the magnetic elastomer different magnetic response behavior. These magnetic elastomer composites obtained by blending have low Young's modulus, approximately 1.5 MPa. Furthermore, when applying the same external magnetic field, BaCo1.2Ti1.2Fe9.6O19/PDMS the magnetic deformation Angle can be as high as 60°. These magnetic elastomers exhibit different magnetic‐induced deformation owing to the adjustable permeability of the magnetic nanoparticles. This research significantly advances the design of applications with specific magnetic characteristics, such as sensors and transducers, thus opening new horizons for innovation in soft robotics and related fields.Highlights All elastomer composite exhibit a low modulus of approximately 1.5 MPa. These composites exhibit different magnetic response behaviors. This research provides a solution for the innovation of transducers.

Magnetically Driven Quadruped Soft Robot with Multimodal Motion for Targeted Drug Delivery.

Untethered magnetic soft robots show great potential for biomedical and small-scale micromanipulation applications due to their high flexibility and ability to cause minimal damage. However, most current research on these robots focuses on marine and reptilian biomimicry, which limits their ability to move in unstructured environments. In this work, we design a quadruped soft robot with a magnetic top cover and a specific magnetization angle, drawing inspiration from the common locomotion patterns of quadrupeds in nature and integrating our unique actuation principle. It can crawl and tumble and, by adjusting the magnetic field parameters, it adapts its locomotion to environmental conditions, enabling it to cross obstacles and perform remote transportation and release of cargo.

Statistical and numerical analysis of magnetic field effects on laminar natural convection heat transfer of nanofluid in a hexagonal cavity

This paper presents a statistical and numerical investigation that examines the optimization and sensitivity analysis of the unsteady laminar natural convective heat transfer flow of Fe3O4-water nanofluid in a hexagonal cavity considering the impacts of a sloping magnetic field in one-component nanofluid model. The inclined walls of the cavity are maintained at a constantly low temperature, while the bottom wall is uniformly heated. The upper wall, however, is regarded as adiabatic. The nanofluid thermal conductivity model incorporates the impact of Brownian motion. The Galerkin weighted residual finite element method has been employed to solve the governing dimensionless equations. The results are provided regarding the average Nu, streamlines, and isotherms. The study uses response surface methodology to analyze the sensitivity of parameters such as the Ha, Ra, and nanoparticle volume percentage. Using a response surface policy allows for optimizing the process and identifying the most favorable circumstances to achieve the maximum thermal transfer rate. The flow pattern of the nanofluid is significantly affected by the magnetic field and its alignment. The numerical results indicate a significant rise in the average Nu as the nanoparticle volume percentage, magnetic field inclination angle, nanoparticle type factor, and Ra increase. Conversely, the Hartmann number and the nanoparticle's diameter have contrasting effects. When considering Brownian motion, the average Nu grows by 225.89 % for Ra = 106 with ϕ = 0.03 and 25.28 % for the other case. The optimal condition for heat transfer occurs when Ra = 106, Ha = 4, and ϕ =0.03 while keeping the other parameters constant.

A macroscopic magneto-optical response resulting from local effects in ferronematic liquid crystals.

This study investigates the magneto-optical response of liquid crystals (LCs) with planar anchoring in the presence of γ-Fe2O3 magnetic nanoparticles (MNPs). This research demonstrates the formation of novel magnetic composite chains of LCs wrapped around γ-Fe2O3 MNP chains within the LC matrix under an applied magnetic field. These composite chains exhibit a distinct magneto-optical response, characterized by changes in birefringence and dichroism as the magnetic field direction is altered. Based on experimental findings, a two-subsystem model and an effective volume fraction of composite chains are proposed to describe the magneto-optical behavior of the γ-Fe2O3 MNP-doped LCs. The first subsystem comprises the LC matrix, which retains its inherent anisotropic optical properties and does not respond to the applied magnetic field. The second subsystem consists of the magnetic composite chains, which exhibit a distinct magneto-optical response due to their rotational alignment with the magnetic field. The difference in absorbance, 2αdd, which corresponds to dichroism, decreases with increasing magnetic field angle Θ, indicating a corresponding change in dichroism. This interplay between the two subsystems leads to the macroscopic magneto-optical response observed in the γ-Fe2O3 MNP-doped LCs. Due to the stability of the composite chains, the magneto-optical response is stable and can be reversed.

Position Servo Control of Electromotive Valve Driven by Centralized Winding LATM Using a Kalman Filter Based Load Observer

The exhaust gas recirculation (EGR) valve plays an important role in improving engine fuel economy and reducing emissions. In order to improve the positioning accuracy and robustness of the EGR valve under uncertain dynamics and external disturbances, this paper proposes a positioning servo system design for an electromotive (EM) EGR valve based on the Kalman filter. Taking a novel valve driven by a central winding limited angle torque motor (LATM) as the object, we have fully considered the influence of the motor rotor position and load current, as well as the magnetic field saturation and cogging effect, improved the existing LTAM model, and derived accurate torque expression. The parameter uncertainty of the above internal model and the external stochastic disturbance were unified as “total disturbance”, and a Kalman filter-based observer was designed for disturbance estimations and real-time feed-forward compensation. Furthermore, using non-contact magnetic angle measurements to obtain accurate valve position information, a position control model with real-time response and high accuracy was established. Numerous simulated and experimental data show that in the presence of ± 25% plant model parameter fluctuations and random shock-type disturbances, the servo system scheme proposed in this paper achieves a maximum position deviation of 0.3 mm, a repeatability of positioning accuracy after disturbances of 0.01 mm, and a disturbance recovery time of not more than 250 ms. In addition, the above performance is insensitive to the duration of the disturbance, which demonstrates the strong robustness, high accuracy, and excellent dynamic response capability of the proposed design.

Numerical simulation of dynamic loss and total loss in the REBCO tapes under perpendicular AC magnetic fields up to 8 T at 20 K and 50 K

REBCO tapes carry DC current under AC magnetic fields in proposed HTS fusion applications. AC loss will be generated in the process and it is important to understand the AC loss behaviour for safe operation of the fusion magnets. In this work, magnetisation loss (Qm), dynamic resistance (Rdyn), and total loss (Qtotal) in four different REBCO tapes are numerically studied, using the measured JcB,θ and nB,θ, for the magnetic field amplitude applied perpendicularly up to 8 T at 20 K and 50 K, where JcB,θ represents the magnetic field and field angle (θ) dependent critical current density. The peak of Theva JcB,θ data is different from that of other tapes. We artificially shifted the ab-plane peak of Theva JcB,θ to the left by 25° to match the peak value. The newly shifted data is named as Theva-shift, which was also investigated to study the influence of the Theva peak shift on AC loss. The normalised DC transport current level (i = It/Ic0) ranges from 0.05 to 0.9, where the DC current amplitude and the self-critical current of the tape are represented by It and Ic0, respectively. The simulation results show that the AC losses deviate significantly from the Brandt-Indenbom (BI) equation at high magnetic fields. Jc and instantaneous loss curves for different tapes show correlation at high magnetic fields. The simulation results also show how different JcB,θ characteristics for different tapes influence AC losses. When AC loss values are scaled by the self-field critical current, Qm without current and Qtotal with current in the different tapes show a good agreement. It implies that the temperature dependence of the two types of loss can be calculated from a known loss at one temperature and the self-field critical current.

Analysis of magneto-natural convection and second law of thermodynamics of Cu-Al2O3-hybrid nanofluid in a vertical wavy cabinet having a localized non-uniform heat source

Improvements in thermal transference rate and minimization of entropy generation are critical issues in many industrial and engineering applications where heat transfer coefficient is essential to achieve optimal performance and minimal energy consumption. In the present investigation, a computational analysis has been conducted to analyze the impact of magnetic field on magneto-free convection and entropy generation inside a vertical wavy cabinet filled by Cu-Al2O3/H2O hybrid nanosuspension. In the geometry of this model, vertical boundaries of the chamber are designed as wavy and kept as cooled temperature (Tc), whereas the horizontal boundaries are modeled as square and are designed to be thermally adiabatic, except the centrally heated portion on the bottom wall. The centered bottom heated section is supposed to be isothermal with linearly changing temperature, and it changes linearly from Th1 to Th2, whereas it is modelled as a non-isothermal condition. The main focus, in this investigation, is on the entire chamber filled with the combination of hybrid nanoparticles regarded the volumetric concentration of copper and alumina nanoparticles (Cu-50 %+Al2O3-50 %) along with base liquid (H2O). The transformed dimensionless partial differential equations were solved by using finite volume method (FVM) with power law differencing scheme. The simulated flow and temperature fields are scrutinized by streamlines, isotherms, entropy formations, total entropy generation and average convective Nusselt number associated with varying number of undulations (0 ≤ N≤3) volume fraction of hybrid nano liquid (0 ≤ φ ≤ 0.04) magnetic orientation angles (0° ≤ ς ≤ 135°), Hartmann number (Ha = 0 and 50), and dimensionless temperature drop (Ω = 0.001–0.1). From this study, it is found that the average Nusselt number and entropy generation increase as the solid volume fraction of hybrid nanoadditives increases, while opposite trend is observed when the values of Hartmann number rises. The findings show that growth of undulation number (N) causes the reduction of convective heat transfer rate as well as average entropy production intensity. The obtained outcomes concluded that hybrid nano liquid is more effective and finest choice for the improvement of cooling of heat transfer process and minimal energy loss than single nanoliquid. According to the new proposed criterion (TPC), the results show that square-shaped enclosure (N=0) manifests the better cooling performance among the considered governing parameters. The novelty of this study is to scrutinize the flat/ vertical wavy boundaries of the cabinet which can be represented as a model of heat transfer controller, in which it manages the thermal and flow field characteristics. Predominantly, the isothermal line source is used to boost the overall convective heat transfer which is applied in buildings and fluid-mounted heaters. Additionally, many investigators have focused only on the enhancement of heat transfer. As it is known, to increase the thermodynamic efficiency of a system, optimization of entropy generation is an excellent tool which reduces the loss of energy. Hence, it recently does a good engineering sense to highlight an entropy irreversibility.

Synergistic effects of multi-segmented magnetic fields, wavy-segmented cooling, and distributed heating on hybrid nanofluid convective flow in tilted porous enclosures

This study investigates the complex thermal-fluid behavior within a tilted porous enclosure filled with a Cu−Al2O3-water hybrid nanofluid, subject to segmented magnetic fields, wavy cooling segments, and distributed heat sources. The research explores the intricate interplay between geometric factors and thermal-magnetic forces to enhance heat transfer in industrial applications. The finite volume method (FVM), coupled with the SIMPLE algorithm and a TDMA solver, is employed to solve the governing transport equations. A comprehensive parametric analysis examines the effects of key dimensionless parameters: Darcy-Rayleigh number (10–104), Darcy number (10-4–10-1), Hartmann number (0–70), magnetic field angle (0°-180°), nanoparticle volume fraction (0–2 %), porosity (0.1–1.0), wavy cooler undulation height (0–0.3), magnetic segment width (0–1), number of segmental magnetic fields (0–4), and enclosure tilting angle (0°–180°). The study elucidates the physical mechanisms underlying the transition from uniform to segmented heating scenarios. Results reveal a remarkable enhancement of up to 38 % in heat transfer performance when transitioning from a conventional square enclosure to the proposed configuration with partial waviness on opposing walls. This improvement stems from increased surface area and disrupted thermal boundary layers, promoting better fluid mixing. The application of a segmented magnetic field with strategic orientation resulted in up to 26 % enhancement by modulating flow patterns and creating localized convection cells. The segmented heating generates thermal plumes that interact with the magnetic field-induced Lorentz forces, further improving thermal transport. The findings provide valuable insights into the design and optimization of efficient heat transfer systems in various industries, including electronics cooling, solar thermal collectors, and nuclear reactors, demonstrating significant potential for energy savings and improved thermal management through the strategic integration of hybrid nanofluids, magnetic fields, and geometric modifications in porous media applications.

Magnetic field enhanced laser absorption on a metallic surface incorporated with shape-dependent nanostructures

Abstract This communication proposes an analytical model to investigate the nanoparticle-based nonlinear absorption phenomenon associated with an obliquely incident p-polarized laser beam on a metallic surface. In this scheme, the surface is ingrained with noble-metal spherical nanoparticles and cylindrical nanoparticles in the presence of an external static magnetic field. The absorption of laser energy in the presence of nanoparticles (NPs) is attributed to surface plasmon resonance and enhanced magnetic-field effects. The absorption phenomenon is significantly enhanced by the incorporation of nanostructures and a magnetic field. The ellipticity characterizing parameter, which significantly influences the resonant frequency of different nanometric structures, has also been analysed and discussed. The effects of varying the magnetic field intensity, incident angle, size, and spacing of the NP were examined to determine their influence on the anomalous absorption of the laser. Furthermore, a direct dependency was found between the absorption coefficient and transmission coefficient of the incident laser, as well as the dimensions of the NPs. Several applications have direct relevance to this study, including biosensors such as DNA sensors and immunosensors, photothermal therapy, photoacoustic imaging, optoelectronic devices, solar cells, and surface-enhanced Raman spectroscopy.