Concentration, susceptibility, and specific heat are fundamental topics in thermodynamics and materials science, since they affect material responses to variations in temperature and concentration. These qualities are essential for optimizing chemical processes, engineering systems, and environmental applications that require precise control over energy transfer and reaction behavior. In combination, active and passive control strategies provide significant tools for modifying nanomaterial performance, allowing designs to efficiently govern transport processes and help to create solutions in developing technologies and healthcare applications. Inspired by these applications, this study investigates the unsteady magnetohydrodynamic flow of electrically conducting Boger fluid over a slowly rotating stretching disk under active and passive nanoparticle control, incorporating concentration susceptibility, Soret-Dufour, and specific heat effects. The governing equations are transformed into ordinary differential equations (ODEs) and solved using a Fibonacci Wavelet-based collocation technique, with validation against the Runge-Kutta-Fehlberg fourth- and fifth-order methods. The results reveal that increasing the solvent fraction enhances both radial and tangential velocity, whereas higher relaxation time and magnetic parameters suppress the flow due to viscoelastic resistance and Lorentz forces. Thermal and concentration fields are significantly influenced by thermophoresis, Brownian motion, and cross-diffusion effects, with active control yielding superior heat and mass performance compared to passive control. These findings provide deeper insights into controlled nanofluid transport relevant to thermal management and hydrogen energy systems.

Any micropolar fluid containing magnetic particles, such as blood and ferrofluids, under the influence of an applied magnetic field experiences a magnetic torque resulting from the misalignment between the magnetization of these particles and the magnetic field, called micromagnetorotation (MMR). Although critical in such fluids, MMR remains underexplored in blood flows, where erythrocyte magnetization is often neglected. To address this, two transient OpenFOAM solvers were developed: epotMicropolarFoam, for incompressible, laminar MHD micropolar flows, and epotMMRFoam, which extends the former by incorporating MMR. In epotMicropolarFoam, the PISO algorithm is used for pressure-velocity coupling, while the low-magnetic-Reynolds-number approximation is adopted for the MHD phenomena simulation. Micropolar effects are included by incorporating the microrotation-vorticity difference in the momentum equation, and solving the internal angular momentum equation. EpotMMRFoam also uses the PISO algorithm and the low-magnetic-Reynolds-number approximation with the MMR term included in the internal angular momentum equation. In this solver, a constitutive magnetization equation is also solved. Validation against the analytical MHD micropolar Poiseuille flow showed excellent accuracy (error <2%). Including MMR caused notable reductions in velocity (up to 40%) and microrotation (up to 99.9%), especially under strong magnetic fields and high hematocrit values. Without MMR, magnetic effects were minimal due to the blood's low electrical conductivity. The simulations of 3D MHD artery and 2D MHD aneurysm flows supported these results. Especially in the aneurysm, MMR suppressed any recirculation cores, highlighting its stabilizing and shear-dampening effects. The solvers show strong promise for biomedical applications such as magnetic hyperthermia and targeted drug delivery. Program summary. Program Title: epotMicropolarFoam, epotMMRFoam. CPC Library link to program files:https://doi.org/10.17632/3c6twd899c.1. Developer's repository link (epotMicropolarFoam): https://github.com/KEAslani/epotMicropolarFoam. Developer's repository link (epotMMRFoam): https://github.com/KEAslani/epotMMRFoam. Licensing provisions: GPLv3. Programming language: C++. Nature of problem: There are no numerical codes for simulating micropolar flows with or without magnetic particles under the influence of applied magnetic fields. When magnetic particles exist in the fluid (e.g., ferrofluids and blood), the effect of micromagnetorotation should be included in the code, i.e., the magnetic torque that arises from the misalignment between the magnetization and the applied magnetic field. Solution method: Two transient OpenFOAM solvers were created, i.e., epotMicropolarFoam and epotMMRFoam, to simulate magnetohydrodynamics micropolar flows without or with magnetic particles, respectively. Both solvers utilize the PISO algorithm for pressure-velocity coupling, while adopting the low-magnetic-Reynolds-number approximation (electric potential formulation) for the MHD simulations. In the case of epotMMRFoam, the micromagnetorotation term is also included in the change of internal angular momentum equation, while a constitutive equation for the magnetization is also included.

The present analysis elucidates the impact of low-oscillating and high-oscillating magnetic fields on the tetra hybrid nanofluid flow past a rough revolving disk. Additionally, the influence of nonlinear thermal radiation and non-uniform heat source/sink on the fluid flow is considered to evaluate the heat transport attributes. The classical von Karman issue of a revolving disk is examined with partial slip at the disk surface. The similarity variables are used to convert the governing partial differential equations (PDEs) into ordinary differential equations (ODEs). Furthermore, the resultant ODEs are solved numerically using the Runge-Kutta Fehlberg's fourth-fifth order (RKF-45) approach. Moreover, the Levenberg{Marquardt artificial neural network (LM-ANN) is employed to assess the heat transmission rate for various parameters. Also, the results of RKF-45 are compared with the outcomes of the LM-ANN technique. A sensitivity analysis is performed using response surface methodology (RSM) with analysis of variance (ANOVA) to investigate the heat transport rate for various parameters. The graphical depictions are utilized to investigate the notable impact of several dimensionless parameters on the thermal and velocity profiles. The comparison of the low-oscillating magnetic field and high-oscillating magnetic field for various parameters on the velocity profile is elucidated in this study. The rise in the thermal radiation parameter, along with temperature-and space-dependent heat source/sink parameters, increases the temperature profile.

The present study develops a hybrid analytical-computational approach to the thermal transport study of Reiner–Rivlin nanofluid flow with Arrhenius activation energy effects, aligning with UN Sustainable Development Goals 9 (Industry, Innovation, and Infrastructure) and 12 (Responsible Consumption and Production). The governing nonlinear partial differential equations are reduced to a coupled system of ordinary differential equations via Lie group transformations and solved numerically. An artificial neural network (ANN), trained using the Levenberg–Marquardt algorithm, is integrated with a modified Garson sensitivity analysis to quantify the effect of important parameters on the heat transfer. The ANN model exhibits excellent prediction accuracy with an overall correlation coefficient R=0.99977 . Results show that the thermal Biot number yields the highest positive impact, increasing the heat transfer rate by 54.61

The increasing requirement for highly effective thermal systems in situations where traditional fluids are unable to provide sufficient heat transfer performance is the motivation behind this research. Due to this, the synergistic interaction of many nanoparticles results in tetra-hybrid nanoliquids with better thermal conductivity, making them appealing for enhanced heat transfer applications. Furthermore, many real-world technological structures in which surface movement and instability greatly affect transport features are modelled by flow in active parallel plates. Inspired by these applications, this analysis examines the influence of a magnetic field on heat transfer and unsteady flow of tetra-hybrid nanofluid between two active parallel plates subjected to a porous medium and heat source/sink. Further, the linear, nonlinear, and quadratic thermal radiation models are used to assess their comparative influence on temperature distribution and heat transfer efficacy. This work pertains to applications like temperature regulation in tiny electromechanical structures, the cooling for electrical and nuclear-powered devices, and energy transmission in porous materials where magnetic regulation of nanofluid flow is critical. The governing partial differential equations characterizing momentum and energy flow are derived by integrating the effects of porous resistance and thermal radiation and are reduced to ordinary differential equations via similarity transformations. The Legendre polynomial collocation method (LPCM) is used to solve the resulting equations. Further, the artificial neural network (ANN) is employed to assess the thermal profile with linear, nonlinear, and quadratic thermal radiation cases. The consequence of various factors on the thermal and flow field is depicted graphically.

This study presents a numerical investigation of a three-dimensional (3D) micropolar magnetohydrodynamic (MHD) blood flow through stenosis, with and without the effects of micromagnetorotation (MMR). MMR refers to the magnetic torque caused by the misalignment of the magnetization of magnetic particles in the fluid with the magnetic field, which affects the internal rotation (microrotation) of these particles. Blood can be modeled as a micropolar fluid with magnetic particles due to the magnetization of erythrocytes. In this manner, this study analyzes important flow features, i.e., streamlines, vorticity, velocity, microrotation, wall shear stress (WSS), and pressure drop-under varying stenosis, hematocrit levels, and magnetic fields, using two newly developed transient OpenFOAM solvers: epotMicropolarFoam and epotMMRFoam. Results indicate that micropolar effects become more pronounced at severe stenosis due to the significant reduction in artery size, resulting also in higher WSS and pressure drop. Furthermore, when MMR is disregarded, the magnetic field does not significantly alter blood flow, regardless of its intensity, due to the minimal impact of the Lorentz force on blood. Conversely, MMR substantially affects blood flow, particularly at higher hematocrit levels and severe stenoses, leading to reductions of up to 30% in velocity and vorticity and up to 99.9% in microrotation and higher WSS and pressure drop. Simultaneously, any vortices or disturbances are dampened. These findings underscore the critical role of MMR (which was ignored so far) in altering flow behavior in stenosed arteries, suggesting that it should be considered in future MHD micropolar blood flow studies.

The oscillatory motion of graphene oxide-Go nanoparticles in water lubricating Maxwell nanofluid flow for heat and mass transfer enhancement in steady and fluctuating regime is important significance of this study. The aim of this work indicates the temperature distribution, nanoparticle concentration rate and velocity field around stretching radiating-cylinder in drilling systems. The nonlinear radiating energy, entropy generation, mixed convection, buoyancy ratio and oscillatory effects are assumed for heat and mass performance. The partial differential based mathematical expressions are developed to estimate the values of current analysis. The oscillatory stokes conditions, complex variables, and primitive transformations are applied to develop steady and fluctuating results. The computational outputs are secured using very efficient methods like finite difference and Gaussian elimination. The graphical outputs are displayed through TecPlot-360 and FORTRAN. The fluid velocity field, energy, and concentration outputs are executed with the help of various physical factors. The steady friction and steady thermal rate are depicted and are used in transient algorithm to depict the fluctuating friction rate and oscillatory thermal-mass transport. The magnitude of fluid velocity, fluid temperature and fluid concentration enhances as Maxwell parameter is enhanced. The variation in fluid velocity amplitude and fluid temperature increases as radiating energy is enhanced. For high parametric range of Maxwell number, the steady skin friction and mass transfer increases but heat transfer decreases. At smaller Eckert number, the oscillations in transient skin friction, transient heat and mass transfer are enhanced. At higher Maxwell parameter, buoyancy and Schmidt number, the large amplitude in heat and mass oscillations is observed.

The rapid growth of industrialization and the depletion of global water resources have made the treatment and reuse of hazardous industrial effluents crucial for sustainable water management, directly supporting the Clean Water and Sanitation Sustainable Goals. As conventional treatment technologies have continued to be both expensive and energy consuming, biologically assisted technologies present environmentally friendly and scalable alternatives. This research has developed a new bio-rheological modeling framework to simulate the flow of effluents and the mechanisms used to transport pollutants based on microrotation induced by microbial motility combined with the non-Newtonian Casson fluid behavior of effluents. The bio-rheological model incorporates the complex physical, thermal, and biologically based interactions of microbial motility, heat, and hazardous contaminant transport through molecular-based nonlinear radiation, Arrhenius rate law reaction kinetics, and thermo-diffusive effects. Using a Central Composite Design based deep neural network (DNN) model, we can predict key engineering quantities such as heat and mass transfer rates, and rates of microbial motility with greater accuracy and efficiency than achieved with conventional analytical and empirical methods. In fact, the DNN model produced R² values of 0.9989 for the heat transfer rate, 0.9996 for the mass transfer rate and 0.9993 for the density of microbial motility, which demonstrates that the DNN provided an accurate representation of the real-world physical, thermal, and microbiological interactions between effluents and their associated pollutants. This integrated biofluid-AI approach provides practitioners with a data-driven and sustainable framework to optimally design and implement biological treatment systems for industrial effluent with minimal cost, energy consumption, and environmental impact.

Biodiesel’s application in compression–ignition engines is mostly limited by the type of methyl esters it contains rather than the total amount of feedstocks. In order to modify the fatty acid methyl ester (FAME) profile for better combustion and emissions, cottonseed (CSOME), neem (NOME), and orange peel oil methyl esters (OPOMEs) were carefully mixed. Fuel chemistry was examined using Gas Chromatography–Mass Spectrometry (GC-MS) and Fourier Transform Infrared (FTIR), which confirmed variations in oxygenated functional groups, saturation levels, and volatility. In a single-cylinder CI engine, diesel, single, binary, and ternary biodiesel mixes were tested over 25–100% load at compression ratios of 17 and 18, both with and without 10% EGR. The ester-optimized ternary blend HBO70 delivered the best overall performance at CR 18 with EGR, exhibiting only a 0.61% reduction in BTE while achieving significant reductions in smoke (44%), PM (51%), NOx (30%), HC (11%), CO (10%), and specific fuel consumption (SFC) (6.8%). Regression analysis confirmed a temperature- and oxygen-controlled NOx–PM trade-off, demonstrating that ester-profile optimization is an excellent way to achieve cleaner and more efficient CI engine operation.

This work investigates the role of an active Navier-Stokes angular term, inherent in micropolar theory, in characterizing small-scale turbulence behavior. By incorporating the micropolar viscosity ratio m, a modified Navier-Stokes equation is derived that allows for fine-tuning of small-scale turbulence intensity without changing the bulk flow properties. Direct numerical simulations of turbulent micropolar Poiseuille flow show that increased m intensifies the near-wall turbulence and enhances dissipation of turbulent kinetic energy, particularly within the viscous sublayer. The decisive role of small-scale structures in micropolar flows is further enhanced here by the analysis of helicity, where acceleration of velocity-vorticity alignment is observed. The outcome underlines the potential of a micropolar model in advancing studies and modeling of turbulence.

The thermal efficiency of tetra-hybrid nanofluids exposed to a horizontal magnetic field over a stretched revolving disk has significant potential for enhanced cooling and energy-related applications. Such fluids, formed by dispersing multiple nanoparticles within a base fluid, offer enhanced heat transfer suitable for turbine blade cooling, compact electromagnetic heat exchangers, and biomedical thermal control systems. In this study, the three-dimensional flow of a tetra-hybrid nanofluid over a rotating stretchable disk is analyzed by accounting for the combined influence of a horizontal magnetic field, porous medium, thermal radiation, and internal heat sink/source under convective boundary conditions. The governing equations are transformed into ordinary differential equations (ODEs) and solved numerically using the Runge-Kutta-Fehlberg-Fourth-Fifth (RKF-45) method. To maximize the heat transfer rate, the Taguchi-based statistical method, combined with signal-to-noise ratio analysis and analysis of variance (ANOVA), is employed. The results reveal that increasing magnetic field strength and porosity significantly suppress both tangential and radial velocities due to enhanced resistive forces. Quantitatively, the optimization predicts a maximum Nusselt number of 10.4844123215026. The ANOVA results show that the rotational parameter dominates heat transfer enhancement with a contribution of 86.86%, while the Biot number has a minimal influence of only 0.30%. These findings provide useful design guidance for controlling thermal performance in magnetically regulated cooling systems and high-efficiency thermal management devices.

This is an erratum to our published paper Reference [...]

This article deals with the heat and mass transfer analysis of Casson hybrid nanofluid flow over a curved Riga surface with slip conditions in the presence of gyrotactic microorganisms. The mechanism of Soret and Dufour effects, exothermic/endothermic catalytic reaction, and an exponential heat source are also investigated. The mixture of aluminum oxide and multi‐walled carbon nanotubes with Therminol‐VPI fluid is assumed as the hybrid nanofluid. Boundary layer assumptions are taken in the mathematical modeling of governing equations. Transformation variables are introduced to get the dimensionless governing equations. Numerical simulation of the transformed equations is done with the help of the Matlab computational tool using the Cash and Carp numerical method. Numerical results corresponding to the influential factors are plotted in graphs for velocity profile, temperature profile, concentration profile, drag coefficient, Nusselt number, Sherwood number, and entropy generation. It is observed that the fluid velocity diminishes with an enhancement in the curvature parameter, and fluid velocity enhances with an improvement in the suction parameter. Thermal profile improves for enhancing modified magnetic field parameter and drops with an increase in exponential index parameter. The microorganisms respond to temperature and concentration gradients, affecting the overall heat and mass transfer dynamics. This research aims to reveal the coupled effects of heat transfer, diffusion, and microorganism behavior in computational simulations, which have various applications in different sectors like electronics, chemical engineering, and material science.

The topic of the present study is the aerodynamic performance of a Natural Laminar Flow (NLF) wing for UAVs at low speed. The basis is a thoroughly tested NLF airfoil in the wind tunnel of NASA which is well-customized for light aircrafts. The aim of this work is the numerical verification that a typical wing design (tapered with moderate aspect ratio and wash-out), being constructed out of aerodynamically highly efficient NLF airfoils during cruise, can deliver high aerodynamic loading under minimal freestream turbulence as well as realistic atmospheric conditions of intermediate turbulence. Thus, high mission flexibility is achieved, e.g., short take off/landing capabilities on the deck of ship where moderate air turbulence is prevalent. Special attention is paid to the effect of the Wing Tip Vortex (WTV) under minimal inflow turbulence regimes. The flight conditions are take off or landing at moderate Reynolds number, i.e., one to two millions. The numerical simulation is based on an open source CFD code and parallel processing on a High Performance Computing (HPC) platform. The aim is the identification of both mean flow and turbulent structures around the wing and subsequently the formation of the wing tip vortex. Due to the purely three-dimensional character of the flow, the turbulence is resolved with advanced modeling, i.e., the Improved Delayed Detached Eddy Simulation (IDDES) which is well-customized to switch modes between Delayed Detached Eddy Simulation (DDES) and Wall-Modeled Large Eddy Simulation (WMLES), thus increasing the accuracy in the shear layer regions, the tip vortex and the wake, while at the same time keeping the computational cost at reasonable levels. IDDES also has the capability to resolve the transition of the boundary layer from laminar to turbulent, at least with engineering accuracy; thus, it serves as a high-fidelity turbulence model in this work. The study comprises an initial benchmarking of the code against wind tunnel measurements of the airfoil and verifies the adequacy of mesh density that is used for the simulation around the wing. Subsequently, the wing is positioned at near-stall conditions so that the aerodynamic loading, the kinematics of the flow and the turbulence regime in the wing vicinity, the wake and far downstream can be estimated. In terms of the kinematics of the WTV, a thorough examination is attempted which comprises its inception, i.e., the detachment of the boundary layer on the cut-off wing tip, the roll-up of the shear layer to form the wake and the motion of the wake downstream. Moreover, the effect of inflow turbulence of moderate intensity is investigated that verifies the bibliography with regard to the performance degradation of static airfoils in a turbulent atmospheric regime.

Rotating disks have major applications in the engineering and industrial sectors. In engineering, kinetic energy is converted to thermal energy using the rotating disk, particularly in vehicle braking systems. Nanofluids have a variety of uses in heat transfer, including fuel cells, electrical devices, hybrid engines, medical procedures and residential refrigerators. High-oscillating magnetic fields are important because of their impact on scientific and technological advancement. Inspired by these applications, the current research inspects the effect of a high-oscillating magnetic field on the time-dependent flow of nanofluid across a slow-rotating disk with permeable media and nanoparticle aggregation. Additionally, the influence of thermal radiation, heterogeneous-homogeneous chemical reactions, suction and heat source/sink are considered in the analysis. The governing partial differential equations (PDEs) are converted into dimensionless ordinary differential equations (ODEs) using appropriate similarity variables. Runge-Kutta Fehlberg's fourth-fifth order (RKF-45) scheme is employed to solve the obtained ODEs numerically. The comparison of fluid flow with nanoparticle aggregation and without aggregation cases for various parameters is shown graphically. For the porosity parameter, skin friction is enhanced by approximately 15.2% for the case without aggregation and 16.55% for the case with aggregation. The velocity profiles drop as the Brownian relaxation time's value rises. The thermal profile increases with the rising values of the heat generation/absorption parameter.

The current investigation explores the influence of the magnetic field on the Boger micropolar liquid motion over a curved stretchable sheet. Further, the mass and heat transportation attributes are analyzed with the significance of heat source/sink, nonlinear thermal radiation, and pollutant concentration. Micropolar liquids are more complicated than Newtonian liquids and represent real-world materials such as polymers and biological liquids. Understanding how contaminants alter these fluids' microstructure and flow behaviour is critical for medical care, biology, and materials research uses. The governing partial differential equations (PDEs) are converted to dimensionless ordinary differential equations (ODEs) using similarity variables. Furthermore, the obtained ODEs are solved using the Runge Kutta Fehlberg’s fourth-fifth order (RKF-45) approach. Moreover, the effects of several dimensionless parameters on the various profiles are depicted in graphs. The increase in the material parameter and relaxation time ratio decreases the velocity profile. As the values of thermal radiation and heat sink/source parameters increase, the temperature profile intensifies. The increase in values of the pollutant external source parameter increases the concentration profile. As the Schmidt number values increase, the concentration profile reduces.

The thermal activity of various base liquids can be enhanced by hybrid nanofluids since they are more reliable and stable. Compared to simple nanofluids, which have uses in the engineering and industrial sectors, hybrid nanofluids are favored because of their significant thermal effects. In light of these worthwhile uses and objectives, this work demonstrated the thermal applications of Boger hybrid nanofluid under the effect of activation energy, quadratic thermal radiation (QTR), and waste discharge concentration. The flow at the oblique stagnation point (SP) due to the stretched cylinder has been considered. The oblique SP flow pattern is an intriguing phenomenon. Here, the three cases of thermal radiation are considered: (i) linear, (ii) nonlinear, and (iii) quadratic. Similarity transformations convert the governing system of nonlinear differential equations to a system of ordinary differential equations. The results are presented in the current study utilizing the Runge–Kutta–Fehlberg 45 numerical scheme. The graphic findings for many aspects of flow, thermal, and mass transmission are shown and explained. The velocity profile upsurges as the solvent fraction parameter rises. The upsurge in the values of the curvature parameter increases the thermal and velocity profile.

The demand for renewable and environmentally friendly fuels has prompted the exploration of alternative energy sources to replace conventional fossil fuels. This work investigates the optimization of a ternary blend comprising cottonseed oil (CSO), neem oil (NO), and orange peel Oil (OPO) for improved combustion characteristics, enhanced performance, and reduced exhaust emissions. Biodiesels like Cotton Seed Oil Methyl Ester (CSOME), Neem Oil Methyl Ester (NOME), and Orange Peel Oil Methyl Ester (OPOME) were made from CSO, NO, and OPO, respectively. The experimental results show major improvements in thermal efficiency and reductions in key pollutants, including NOx, CO, HC, and smoke. The best blending ratios are determined through a methodical process that employs optimization tools such as Grey Relation Analysis (GRA) with the Taguchi Method and ANOVA for validation. Then, various proportions of these biodiesels were tested in a CRDI engine to optimize the ternary blend proportions. The addition of 10% CSO and 10% OPO to NO reduces NOx emissions by 10% at CR17 as compared to diesel. Brake thermal efficiency improved by 9.08%. HC emission decreased by 10%. Average smoke opacity decreased by 27.65%. Cylinder pressure remains unchanged, but the Net Heat Release rate increased by 2%. Optimum parameters obtained are G2B10 Blend, Load 100%, CR17 and 10% EGR. The findings underscore the potential of this ternary blend as a viable alternative to conventional diesel fuel, with GRA using Taguchi proving to be an effective optimization tool for Multi-Criteria Decision Making (MCDM).

Hyperthermia is a promising medical treatment that uses controlled heat to target and destroy cancer cells while minimizing damage to the surrounding healthy tissue. Unlike conventional methods, it offers reduced risks of infection and shorter recovery periods. This study focuses on the integration of carbon nanotubes (CNTs) within the blood to enable precise heat transfer to tumors. The central idea is that by adjusting the concentration, shape, and size of CNTs, as well as the strength of an external magnetic field, heat transfer can be controlled for targeted treatment. A theoretical model is developed to analyze laminar natural convection within a simplified rectangular porous enclosure resembling a tumor, considering the composition of blood, and the geometric characteristics of CNTs, including the interfacial nanolayer thickness. Using an asymptotic expansion method, ordinary differential equations for mass, momentum, and energy balances are derived and solved. Results show that increasing CNT concentration decelerates fluid flow and reduces heat transfer efficiency, while elongated CNTs and thicker nanolayers enhance conduction over convection, to the detriment of heat transfer. Finally, increased tissue permeability—characteristic of cancerous tumors—significantly impacts heat transfer. In conclusion, although the model simplifies real tumor geometries and treatment conditions, it provides valuable theoretical insights into hyperthermia and nanofluid applications for cancer therapy.