The study focuses on numerical investigation into heat transfer enhancement in a square enclosure occupied with a permeable medium, saturated by nanofluid (Al2O3+TiO2+SiO2/H2O), in the existence of a magnetic field. The finite volume-based marker and cell (MAC) scheme is used to obtain solutions of the governing equations, with a focus on the impact of Rayleigh number (Ra), internal heat generation/absorption (Q), Darcy number (Da) and Hartmann number (Ha) on flow and thermal distribution. The results show that increasing Ra intensifies buoyancy-driven convection, while higher Da values enhance fluid motion and thermal flow. The magnetic field, represented by Ha, stabilizes the flow, reducing convection as Ha increases. Internal heat generation is shown to enhance buoyancy, leading to stronger convective currents. This comprehensive analysis offers valuable insights for the optimization of cooling systems, heat exchangers and other thermal management applications involving porous media, nanofluids and external fields.

As the fast advancement of valleytronics and valleytronic devices, the valley-related transport becomes a research hotspot in graphene. Therefore, we analyze the effect of the magnetic field, the electronic barrier and the strain on the valley-dependent transport of electrons in a graphene in the present work. Based on the results, we find that not only the magnetic field and the electronic barrier but also the strain plays an important effect on the valley-related transport property of electrons, and the large valley polarization can be easily achieved and controlled through changing the magnetic field, the electronic barrier and the strain. This result is very helpful for researchers to understand the valley-related transport mechanism of electrons, and provides a new-alternative method of making valleytronic devices.

The sun is the primary source of thermal energy, and with ongoing advancements in solar technology, it is now widely used in various applications such as photovoltaic cells, solar panels, energy storage systems, solar fabrics, lighting solutions, and water pumping systems. Recently, there has been growing scientific interest in improving the aerodynamic performance of solar-powered aircraft by integrating nanotechnology and solar energy. This study aims to explore the potential of solar aircraft efficiency using these technologies. Specifically, this study investigates the heat transfer characteristics by considering factors such as porous surfaces, convective boundary conditions, solar radiation, a radially varying magnetic field, Ohmic heating, and internal heat generation. The novelty of this study lies in the integration of trihybrid nanofluids ([Formula: see text] and magnetohydrodynamics (MHD) within the field of aerospace engineering, aiming to enhance the durability of both mechanical and electrical aircraft components, ultimately contributing to cost reduction. Using [Formula: see text] to improve heat transfer efficiency and applying MHD to better control thermal management and flow behavior can improve aircraft fuel efficiency, overall performance, and flight range. Furthermore, the originality of this study lies in the incorporation of [Formula: see text] to enhance heat transfer efficiency, along with the application of MHD to improve thermal regulation and control fluid flow behavior. These enhancements have the potential to significantly increase aircraft fuel efficiency, boost overall performance, and extend flight range. It is assumed that THNFs (Engine Oil+SiO2 + Fe3O4+MOS2) travels through the inside of a Parabolic Trough Solar Collectors (PTSCs). The irreversibility analysis of Carreau [Formula: see text] is explored in this investigation. The basic boundary layer equations are simplified by employing a nonsimilar transformation, and the resulting system is tackled through a numerical scheme. The numerical outcomes for different flow variables on velocity, Nusselt number, entropy generation, nanofluid’s temperature, frictional force, and Bejan number are computed and presented through tables and graphs. The outcomes of this examination indicate that raising the values of the heat source, the solar radiation parameter, and the magnetic number enhanced the entropy number and temperature profile. Results reveal that [Formula: see text] are superior in the case of nanofluid (NFs) and hybrid nanofluid ([Formula: see text]. The heat transfer increased by [Formula: see text] and [Formula: see text] for [Formula: see text], [Formula: see text] and [Formula: see text], respectively, compared to the base fluid ([Formula: see text] at a heat generation parameter value of [Formula: see text], indicating enhanced thermal performance with increasing solid content. Similarly, the drag force improved by [Formula: see text] and [Formula: see text] for [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text], respectively, as the magnetic number increased from [Formula: see text]–1.5, confirming the significant influence of magnetic field strength on flow resistance.

This work comprehensively reviews the innovative application of nanofluids as refrigerants in diverse refrigeration systems such as vapor compression refrigeration systems (VCRS), vapor absorption refrigeration systems (VARS), refrigeration based on solar energy, magnetic refrigeration, air-conditioning system and ejector refrigeration technologies. The development of nanofluid shows potential for enhancing efficiency, performance and environmental sustainability in refrigeration systems. This work presents a detailed review of research status in this field and practical applications. Nanofluids are promising candidates for significantly improving heat transfer rates, reducing energy consumption and reducing environmental impact of refrigerants. Special attention is also drawn to the VCRS’s integration, as nanofluids have been noted with improvement in refrigerant properties, assisting in the better performance of lubricants and enhancing heat exchanger efficiency. This review is aimed at the primary objective of analyzing recent findings in nanomaterials with respect to the subject, establishing benefits and challenges existing in the utilization of nanofluids in refrigeration systems.

The exact recursion relations are employed to study the magnetization and phase transition properties by assuming that each site of a Bethe lattice is occupied by two spin-3/2 atoms forming diatomic molecules in the Blume–Capel model. The atoms interact ferromagnetically via three distinct bilinear coupling parameters: intra-site [Formula: see text], nearest-neighbor [Formula: see text] and diagonal inter-site [Formula: see text]. The crystal field (D) is also active at all sites of the Bethe lattice of coordination number three. The thermal variations of the magnetizations are examined at the core molecule to obtain its phase transition properties. The phase diagrams mapped on the [Formula: see text] and [Formula: see text] planes show that the model presents second- and first-order phase transitions. The obtained first-order phase transition line terminating at the isolated endpoints separating the phases ([Formula: see text]) from ([Formula: see text]) is the result of the usual BC phase diagram on the [Formula: see text] plane. The phase diagrams obtained on the [Formula: see text] planes give either only second-order lines, second- and first-order lines, or second- and two first-order lines for given parameters that are not seen in the usual spin-3/2 models.

In this paper, a kinetic model for bidirectional pedestrian flow is proposed and inspired in a one-dimensional evacuation scenario. Walkers exiting the building are assumed mostly passive while the ones moving in the wrong direction are considered aggressive. A two-Boltzmann-moment approach is considered, where densities and mean velocities of each species are the state variables. The corresponding system of transport equations is studied in a linear approximation in two cases: first considering the exiting crowd as being completely passive (intended to simulate a drill) and second, allowing for a disparate aggressiveness in both species (proposed as a real evacuation situation). Stability is found in the first case whereas the second scenario is always unstable. The characteristic time for the onset of instabilities in the second case is established which could be interpreted as the time-frame in which complete evacuation needs to be achieved in order to avoid a congestion in the context of this particular model.

The electronic properties and magnetism for CrxZn[Formula: see text]Se and VxZn[Formula: see text]Se ([Formula: see text]; 12.5%) supercell structures containing 32 and 64 atoms, VyCrxZn[Formula: see text]Se co-substituted supercell structures containing 32 atoms were studied using density functional perturbation theory. Electronic properties predicted the semi-metallic character for CrxZn[Formula: see text]Se, VxZn[Formula: see text]Se and VyCrxZn[Formula: see text]Se. From calculations, it is observed that after the inclusion of the metal atoms into the crystal structure, the band bending characteristics are enhanced and more prominent. The obtained spin moments for VxZn[Formula: see text]Se, CrxZn[Formula: see text]Se compounds with 12.5 and 6.25% concentrations of impurities are 3 and 4[Formula: see text] [Formula: see text], respectively. The co-substituting of vanadium of chromium metals in supercell structure increases the magnetization of VyCrxZn[Formula: see text]Se system. The Curie temperatures are calculated for CrxZn[Formula: see text]Se, VxZn[Formula: see text]Se compounds. Our results predicted that CrxZn[Formula: see text]Se, VxZn[Formula: see text]Se and VyCrxZn[Formula: see text]Se compounds are high Curie temperature diluted magnetic semiconductor materials for application in the production of Zn-based spintronic devices.

This research explores particle deposition driven by thermophoresis in the flow of a Reiner–Rivlin fluid confined between coaxial disks, which undergo simultaneous stretching and rotational motion within their respective planes. The paper aims to derive accurate momentum transport equations for Reiner–Rivlin fluids specific to the current flow problem, addressing inaccuracies present in the existing literature. The study formulates coupled heat and mass transport phenomena, incorporating the thermophoretic deposition effect, which modifies the advection–diffusion equation by introducing additional terms. Two solution methodologies are employed to analyze the resulting similarity equations: (a) the homotopy analytical scheme and (b) MATLAB’s built-in numerical solver. The convergence of the series solution derived from the homotopy approach is demonstrated through the so-called [Formula: see text]-curves. To refine the convergence interval of [Formula: see text], the residuals of all equations are evaluated at the lower boundary. The results confirm that homotopy solutions maintain accuracy beyond six decimal places and exhibit strong agreement with the corresponding numerical solutions. The radial and azimuthal stresses required at the boundaries and particle deposition velocity are scrutinized for a broad range of the material fluid parameter. A notable result is that boosting thermophoretic strength results in a considerable rise in concentration distribution. The cooling rate of the lower disk rises when viscous fluid is replaced with Reiner–Rivlin fluid, and this effect becomes pronounced with a rise in the Reynolds number. As anticipated, graphical representations of particle deposition velocity and axial thermophoretic velocity reveal a direct correlation with the thermophoretic diffusion coefficient.

The magnetic dipole plays a significant role in thermal energy enhancement and heat transfer optimization in systems such as magnetic cooling devices, biomedical therapies, chemical engineering and industrial processes. Due to its significant application, this study investigates the boundary layer flow (BLF) with heat and mass transfer of water-based Prandtl nanofluid containing Zirconium oxide nanoparticles ([Formula: see text] across a horizontal sheet in the presence of a magnetic field produced by a magnetic dipole and nonlinear thermal radiation. The Ferromagnetic interaction and permeable medium porosity are incorporated into the mathematical formulation using the Darcy–Brinkman model and magnetohydrodynamics principles. The modeled problem with corresponding Robin boundary conditions is converted into a system of nonlinear differential equations. The Runge–Kutta (RK-4) scheme is implemented to tickle the governing equations. The finding demonstrates that the flow of a mixture fluid is controlled by implementing the ferromagnetic interaction, and the second-order slip parameter. The temperature uplifts with ferromagnetic interaction, viscous dissipation and the Newtonian heat parameter. The species concentration increases and decreases the function of activation energy and the Stefan–Boltzmann parameter, respectively. The Nusselt enhances up to 16.4% with Eckert number Ec showing significant heat transfer rate. A high mass transfer rate of 15.5% is achieved by the chemical reaction parameter.

Vanadium pentoxide (V2O[Formula: see text] and Vanadium–Molybdenum (V–Mo) mixed oxide nanoparticles are synthesized at 500∘C using a surfactant-free method, with an increase in the atomic percentage of Mo ([Formula: see text], 20%, 30% and 40%) to V. X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM), Raman spectroscopy and Fourier transform infrared spectroscopy (FTIR) were used to characterize the synthesized samples. By using the Debye Scherrer technique and WH plot calculations, the average crystallite sizes and lattice strain assessed from XRD data were found to be almost comparable. SEM detects agglomerated nanoparticle morphology in both pure V2O5 and V–Mo mixed oxide nanoparticles. EDAX confirms the prepared sample’s purity and the presence of its constituent parts. According to diffuse reflectance spectroscopy, the energy band gap was reduced as the amount of Mo in mixed oxide V–Mo nanoparticles rose. The strength of the peak diminishes as the amount of Mo in mixed oxide V–Mo increases on the Raman analysis graph. The presence of V–O and Mo–O functional groups, as well as their formation of pure V2O5 and V–Mo mixed oxide nanoparticles, was confirmed by the FT-IR spectra. Adsorption activity was performed for the dye degradation of methylene blue by pure V2O5 and V–Mo mixed oxide nanoparticles; the percentage of dye degradation removal increased as Mo concentration increased in the V–Mo mixed oxide nanoparticles.