Hybrid nanofluids have emerged as highly effective working fluids in modern thermal engineering due to their exceptional heat transfer aspects. Their capability to enhance efficiency in heating and cooling systems has established them as preferred choice across the wide range of heat management applications. The purpose of this study is to investigate the thermal and flow behavior of a magneto-radiative ternary nanofluid composed of copper, silver, and alumina nanogranules dissolved in blood as base fluid. The intended flow is inspected through a stretchy diverging surface in the presence of electroosmotic forces, momentum and thermal wall slip conditions. The governing equations formulated in wave frame are simplified under small inertia and long wavelength approximations. Numerical solutions of the resulting nonlinear equations are obtained via the shooting technique implemented in Mathematica software. The graphical results offer a comprehensive insight into the flow dynamics. Findings reveal that considerable magnetic effects and an expanded width of electric double layer tend to suppress the fluid motion while leading to an upsurge in temperature close to the channel core part. Additionally, integration of thermal radiation effects, boundary slip effects, and thickened electric double layer contributes to reduction in heat losses inside the channel. A drop in entropy generation and an increment in the Bejan number communicate better heat transfer proficiency and discriminating irreversibility within the flow. Furthermore, the ternary hybrid nanofluid returns the highest enhancement in heat transfer rate compared to conventional blood, thus making it a promising medium for microfluidic and biomedical applications.

Tumor growth within physiological vessels often results in complex flow obstruction due to asymmetric constrictions formed along channel walls. The present work investigates the peristaltic transport in a microchannel containing two tumors of different sizes positioned at distinct axial positions on the upper and lower channel walls. This dual asymmetric tumor configuration enables a detailed examination of the combined influence of tumor size difference and relative position on flow dynamics. A mathematical model is developed under the assumptions of long wavelength and low Reynolds number, which are appropriate for physiological flow at micro scale. Peristalsis is imposed on the channel boundaries, while the tumors are represented as bumps with different sizes and relative positions. Analytical solutions are obtained for the velocity, pressure gradient, volumetric flow rate, shear stress and streamlines. The results demonstrate that tumor size and relative position strongly influence the flow resistance, pressure distribution, and flow characteristics. Higher tumor length and width raise the pressure drop, axial pressure gradients, and wall shear stress while reduce the volumetric flow rate and axial velocity through the constricted region. Also, symmetrically positioned tumors generate more pressure and shear stresses within the microchannel. The study further reveals that tumor size enhances the blockage near the tumor region, and substantially affects the bolus formation and trapping structures. These findings provide the new insights into the hemodynamic consequences of multiple asymmetric tumor-induced obstructions and contribute to a better understanding of physiological fluid flow, targeted drug delivery, and the design of tumor-mimicking microfluidic systems.

Abstract Motile cilia in the respiratory tract generate coordinated beating patterns that drive fluid flow and enable efficient mucociliary clearance. Based on their general structural characteristics, cilia exhibit diverse behaviors under complex hydrodynamic and mechanical interactions. Therefore, this overview reports the latest advances in ciliary biology, covering the most fundamental aspects of ciliary structure, metachronal wave generation, and ciliary beating dynamics. Among the three main modeling frameworks for ciliary propulsion, the single and multicilium mechanical models, ciliary layer and airway surface liquid models, and volume-force models correspond to different modeling styles. From this set of models, we describe the mechanics of tracheobronchial mucus transport and outline contributions from Slender Body Theory, Computational Fluid Dynamics, and other advanced fluid-dynamics modeling approaches. Continuum models of viscoelastic and shear-thinning fluids deserve attention, given their relevance for simulating a realistic respiratory environment. Some future phenomena, including synchronized ciliary beats and metachronal wave propagation, are discussed in light of current modeling efforts that fall short of capturing all the aspects of ciliary function. The review continues by discussing future directions for an integrated approach, filling gaps in modeling efforts through a greater understanding of ciliary transport to improve respiratory health and the treatment of diseases.

As a model for hazardous material pumps, this paper examines the magnetohydrodynamic chemically reacting thermo-solutal peristaltic transport of a non-Newtonian couple stress fluid through a microchannel containing a porous medium. The effects of thermal radiative heat transfer, Joule heating, Soret thermodiffusion, viscous dissipation, and heat generation/absorption are also included. The microchannel walls have convection boundary conditions, and sinusoidal peristaltic waves are considered. The conservation equations for mass, momentum, energy, and concentration are simplified via lubrication approximations. The moving boundary value problem is rendered dimensionless and solved analytically. Numerical evaluations of the axial velocity, temperature, and concentration are conducted in MATLAB. The Bejan number is enhanced with a couple stress (non-Newtonian) parameter, mean flow rate, and Brinkman number. Temperatures are boosted with Hartmann (magnetic) number and Brinkman number but suppressed with the couple stress parameter. The entropy generation parameter is reduced with an increment in couple stress parameter and radiation parameter; whereas it is boosted with the Brinkman number. Pressure gradient is enhanced with an increment in the Hartmann (magnetic) number but depleted with the Darcy number and couple stress parameter. Concentration is strongly reduced in the core zone of the channel with an increment in Soret number, Brinkman number, Hartmann number, mass Biot number, and Schmidt number, but increased with a chemical reaction parameter. Nusselt number magnitudes are elevated with the thermal Biot number, Brinkman number, couple stress parameter, and magnetic parameter but are reduced with an increasing radiation parameter. A substantial modification in bolus size is induced with increasing Hartmann number, Darcy number, and couple stress parameter.

Tumor growth within physiological systems such as the gastrointestinal tract, ducts, or blood vessels can progressively obstruct fluid transport, impair organ function, and reduce the efficacy of therapeutic interventions like drug delivery and hyperthermia. In this study, a mathematical model is developed to investigate and characterize the mechanisms of peristaltic flow in a channel obstructed by transient tumor growth. The model incorporates fundamental conservation laws of mass and momentum, while a bump function is used to represent tumor-induced geometric deformation of the channel wall. In addition, a transverse magnetic field is introduced to account for magnetohydrodynamic effects relevant to biomedical applications such as magnetic hyperthermia. Tumor growth is modeled as a linear time-dependent process, and the flow is analyzed under low Reynolds number and lubrication theory assumptions, which are suitable for physiological flows. Analytical solutions are derived under simplified conditions to examine the influence of tumor growth rate and magnetic field strength on velocity distribution, pressure gradient, wall shear stress, streamline patterns and particle trajectories. The results suggest that early-stage tumor growth produces minimal flow disturbance, whereas progressive enlargement significantly obstructs flow, increases local pressure and skin friction and alters streamline patterns. An increase in Hartmann number enhances magnetic resistance, leading to a reduction in axial velocity and volumetric flow rate. Furthermore, parametric sensitivity analysis reveals that tumor geometric parameters play a dominant role in governing flow behavior compared with magnetic and peristaltic effects.

The study of H1N1 virus particle motion through saliva flow in the esophagus is a key factor in understanding the causes of various esophageal and throat infections. This research is crucial for advancing healthcare diagnostics, enhancing drug delivery systems, and improving infection control strategies. The aim of this study is to examine the influence of buoyancy-driven thermal effects on virus propagation within a confined biological environment. Saliva is modeled as a Jeffrey fluid to represent its viscoelastic rheological behavior. The flow is assumed to be low Reynolds number flow, driven by peristaltic pumping with large wavelength approximation. The energy equation evaluates temperature distribution and its impact on virus propagation, while the momentum equation incorporates thermal buoyancy forces. The Basset-Boussinesq-Oseen (BBO) equation describes the motion of H1N1 virus particles suspended in saliva, accounting for drag, gravity, added mass, and Basset forces. Zero pressure condition is applied at the inlet and outlet boundaries to reflect natural physiological flows. The effects of saliva viscosity, virus diameter, virus density, viscoelastic parameter, Grashof number, heat source parameter, and aspect ratio on velocity field and streamline patterns of saliva movement, and virus transmission, virus velocity, and virus trajectories are analyzed through computational results illustrated by matlab code. Results show that thermal buoyancy significantly alters flow dynamics and virus particle dispersion patterns, providing deeper insights into virus transmission mechanisms in thermally affected biological fluids. These findings have implications for biomedical applications, including targeted drug delivery, disease transmission modeling, and improved medical diagnostics design.

The current study comprehensively investigates Williamson nanofluid flow and transport in an asymmetric porous tapered channel under varying slip conditions, using both analytical and supervised machine learning approaches. This mathematical model integrates thermophoresis, Brownian motion, the Soret and Dufour effects, thermal radiation, and a transverse magnetic field to accurately describe thermosoluble transport phenomena relevant to biomedical contexts. The non-Newtonian Williamson formulation is used to explain how fluids, such as blood, dilute when sheared. Darcy resistance is used to describe porous structures in tissue scaffolds, capillary networks, and dialysis membranes. A perturbation method is used to find analytical solutions that show how key dimensionless parameters affect the profiles of velocity, temperature, concentration, Nusselt number, Sherwood number, skin friction, and pressure gradient. Supervised machine learning models, including artificial neural networks, are also used to predict heat and mass transfer properties and confirm analytical trends with a high degree of accuracy. The results show that increasing the Hartmann number reduces fluid motion due to Lorentz force resistance by approximately 14%, while the Williamson parameter increases shear-thinning and increases velocity by approximately 9%. Thermal radiation significantly broadens the temperature distribution, increasing heat transfer by 12%. The combination of perturbation analysis and supervised machine learning models demonstrates strong predictive power and makes the results more reliable. The integrated analytical-machine learning framework provides essential insights for enhancing nanoparticlemediated drug delivery and advancing hyperthermia cancer treatment through regulated thermosolute transport in porous biological tissues.

Recent advancements in electro-osmotic surface coatings have led to significant theoretical and numerical exploration of how zeta potential influences the electroosmotic flow of viscous ionic fluids over a stretching sheet. The governing boundary layer equations are derived from the fundamental laws of mass, momentum, and energy conservation using appropriate similarity transformations and non-dimensionalization techniques. This system of equations is solved numerically using MATLAB's bvp4c solver. The accuracy of the computational results is confirmed through comparison with previously published studies. To better understand the influence of various parameters on flow and thermal behavior, Response Surface Methodology and Factorial Plot analysis are applied. These statistical tools enable sensitivity analysis by systematically investigating the effects of zeta potential, electroosmosis parameter, electric field strength, and Prandtl number on key flow characteristics such as velocity, temperature distribution, skin friction coefficient, and Nusselt number. The results reveal that the electric field parameter plays a dominant role in enhancing axial velocity and increasing skin friction, making it a key factor in flow dynamics. The zeta potential significantly influences the boundary layer by modifying the electrical double layer and surface charge distribution, leading to noticeable deceleration. Meanwhile, the Prandtl number primarily governs thermal gradients and heat transfer rates, controlling the thermal behavior of the fluid. These physical insights, combined with the optimization capability of Response Surface Methodology, provide actionable guidelines for the design of electroosmotic coating processes and lab-on-chip biomedical devices.

This study numerically investigates the electromagnetic effect on micropolar fluid flow and heat transfer over a stretching sheet with a melting surface and viscous dissipation using an artificial neural network (ANN)-bvp4c approach. The objective is to examine the coupled influence of electromagnetic fields and micropolar fluid behavior on flow and thermal characteristics. The governing equations are solved using ANN and validated with the bvp4c solver to ensure the accuracy and reliability. The novelty of the present work lies in the combined analysis of electromagnetic effect, melting heat transfer, and micropolar fluid dynamics, along with a comparative assessment of ANN and bvp4c methods for boundary value problems (BVPs). The effects of key parameters, including magnetic parameter, electric field parameter, micropolar parameter, Reynolds number, and melting parameter are analyzed. The results reveal that a higher magnetic parameter reduces the fluid velocity due to enhanced resistive Lorentz force, while the electric field parameter and Hall current significantly influence the linear and angular velocities. The velocity profiles indicate that an increase in the micropolar material constant results in lower fluid velocities due to enhanced resistance. Higher melting parameter values reduce both linear velocity and angular momentum, and modify the thermal boundary layer. Comparative results show the excellent agreement between ANN and bvp4c solutions, which confirms the accuracy of the present analysis. Additionally, variations in skin friction and Nusselt number highlight the influence of electromagnetic and thermal parameters on heat transfer characteristics. These findings are relevant to polymer processing, cooling technologies, and magnetohydrodynamic (MHD) applications.

A novel biologically inspired membrane-based pumping system is developed and analyzed for the transport of Jeffery fluids in a vertical convergent-divergent microchannel, embedded within a porous medium and subjected to thermal radiation. This work uniquely explores the impact of the vertical orientation combined with the converging-diverging geometry on fluid dynamics and heat transfer, advancing the understanding of flow behavior in complex microfluidic structures. Applying lubrication theory and nondimensional analysis, the governing mass, momentum and energy equations are solved analytically. The convergent-divergent geometry improves the pressure rise, volumetric flow rates, and velocity profile compared to the uniform channel. On the other hand, the vertical configuration introduces additional effects of buoyancy. The presence of the porous medium increases flow resistance while simultaneously regulating momentum and heat transfer, thereby controlling the velocity, pressure, and temperature distributions. The pumping action due to the periodic membrane oscillations regulates the pressure gradients to facilitate the unidirectional flow. The results also showed that the increase in the Jeffery fluid parameter and the permeability improves the flow rates. On the other hand, the Grashof number enhances buoyancy effects. Thermal radiation reduces the temperature field, while internal heat generation increases it. The entropy generation analysis provides a deeper understanding of the thermodynamic performance of the pumping system. The results of this study provide important insights into the performance of the membrane-driven microfluidic pumps used in various biomedical applications.

Abstract Microscale pumping flow models are important in many industrial and physiological channels related to transport phenomena and engineering applications. A simple example behind the motivation is the rhythmic compression and expansion of channel walls. The membrane pumping mechanism significantly changes flow behavior, which can be used as an artificial pumping mechanism for the movement of biofluid within physiological channels. Motivated by the rhythmic compression and expansion of biological vessels, this study investigates the transition from membrane-driven pumping to peristalsis driven pumping in a microchannel through a unified mathematical wall equation. An incompressible Newtonian viscous fluid flow is analyzed under the influence of transient membrane deformation by incorporating phase lag to capture non-propagative, propagative, and wave-like peristaltic contraction within a unified framework. The fundamental equations for conservation of mass and momentum are considered, and further solved using the lubrication approach along with the low Reynolds number approximation. This study examines the effects of different types of pumping mechanisms including propagative, non-propagative, and wave-like peristalsis contraction on the pressure distribution, velocity distribution, volumetric flow rate, wall shear stress, and streamlines. MATLAB is used to simulate and generate graphical representations. The results reveal that the fluid flow driven by propagative contraction is more as compared to the other pumping mechanisms i.e., non-propagative and peristaltic contraction. The variations in pressure and wall shear stress occur at the contraction region due to the deformation of the membranes. These results provide useful insights into membrane-driven pumping mechanisms in physiological and bio-inspired microfluidic channels.

Valveless membrane contractions-driven pumping has emerged as a promising mechanism for efficient fluid transport in microfluidic and biomedical systems. Particularly when handling electrically conducting and shear-dependent biological fluids. Understanding the significance of nonlinear rheology, slip effects, and magnetic fields together influencing such transport is essential for designing next-generation microscale pumping devices. Existing studies on membrane contraction-driven flows rarely integrate Ree-Eyring shear-thinning behaviour, multi-slip boundary effects, magnetohydrodynamic forcing, and coupled with heat-mass transport effects. As a result, the collective influence of these mechanisms on membrane-driven micro-pumping remains unexplored. A comprehensive mathematical framework is developed to analyse MHD flow of a Ree-Eyring fluid in a deformable membrane microchannel, incorporating velocity, thermal, and concentration slip, along with heat and mass transfer effetcs. The governing equations are formulated from the Navier–Stokes, energy, and species transport laws and reduced to dimensionless form using long-wavelength and low-Reynolds-number approximations. The analytical solutions are derived for velocity, temperature, concentration, shear stress, stream function, and volumetric flow. A parametric analysis is conducted using MATLAB R2024b to quantify the influences of the Ree-Eyring parameter, Hartmann number, and multi-slip conditions. This study demonstrates that shear-thinning rheology, magnetic damping, and interfacial slip provide effective control over pumping performance, thermal regulation, and solute transport in membrane-driven microchannels. These insights provide useful strategies for optimising such microfluidic pumping, thermal management, and biomedical transport processes in electrically conducting non-Newtonian fluids.

Heat transfer and entropy generation in microchannels are crucial to several industrial applications, particularly in device cooling and performance enhancement. These aspects are also significant in healthcare sectors, where microchannel-based systems are employed in processes such as dialysis and diagnostics. The current study investigates these phenomena in a microchannel with a non-uniform rough surface membrane attached to both walls, under the influence of a transverse magnetic field. Unlike conventional peristaltic or smooth-wall microchannel models, the present study focuses on a non-uniform rough-membrane configuration to simultaneously examine its influence on pumping performance, thermal transport, and entropy generation in a Ree-Eyring fluid. This combined analysis provides new insights into the interactions among wall roughness, membrane actuation, magnetic effects, and irreversibility, which have been poorly investigated in the existing literature. By employing a low Reynolds number and long-wavelength approximation, the governing equations are solved analytically to obtain the velocity profile, volumetric flow rate, temperature distribution and entropy generation analysis. Furthermore, the results of the present investigation are demonstrated and analyzed using MATLAB software. The results reveal that the rate of heat transfer is enhanced with the increase in key parameters, in conjunction with the membrane propagation. An increase in entropy generation is observed with rising Brinkman number and heat source parameter; however, this effect can be mitigated by adjusting the temperature difference.

This work examines the magnetohydrodynamic (MHD) slip flow of Jeffrey fluid confined between a stationary lower plate and a moving upper plate, influenced by a uniform transverse magnetic field. The study highlights the interdependent effects of viscoelasticity, wall motion, magnetic field intensity, and velocity slip on the flow dynamics in a micro-channel. Employing lubrication theory, the governing equations are derived and streamlined to yield analytical expressions for the velocity components, pressure distribution, and volumetric flow rate. The influence of the Jeffrey fluid parameters, which denote relaxation and retardation times, is analyzed in conjunction with magnetic and slip characteristics to clarify deviations from Newtonian behavior. Numerical assessments and graphical outcomes, conducted with MATLAB, demonstrate the interaction of these parameters on flow resistance and pressure gradients. The results yield physical insights pertinent to the regulation and enhancement of MHD-driven viscoelastic microfludic and nanofluidic systems.

The effects of a magnetic field, a Hall current, and Joule heating on the peristaltic motion of a mixed convective Jeffrey fluid in a uniform channel are examined here. The study investigates a wide range of slip situations, with several waveforms used to characterize the flow being taken into account. To investigate this intricate phenomenon, we use the ND solution method to numerically solve a set of modified coupled equations under the long wavelength approximation and in the low Reynolds number regime. As well as numerical answers, this study uses graphical and tabular representations to shed light on several critical physical aspects. Some heat and mass movement indicators within the fluid are the skin friction, the Nusselt number, and the Sherwood number. Hall current and Joule heating contribute to an increased temperature field, whereas a more powerful magnetic field slows the flow dynamics. Hall current and the resultant magnetic effect, a fascinating interaction, are dissected in great detail. The intriguing phenomenon of bolus motion is also investigated, providing a fuller picture of this complex flow pattern and its possible uses.

This special issue on “Recent Advances in Fluid Mechanics and Nanoelectronics” presents 14 peer-reviewed research articles, carefully selected from 41 submissions. The selected papers highlight significant progress in fluid mechanics, covering theoretical modelling, computational techniques, experimental insights, and emerging applications. These articles were presented at the 2nd International Conference on Recent Advances in Fluid Mechanics and Nanoelectronics (ICRAFMN-2024), showcasing the interdisciplinary nature and technological relevance of the work. The studies demonstrate innovations with wide-ranging implications in energy systems, aerospace engineering, microelectronics, and biomedical devices. This issue provides a timely overview of the current research landscape and identifies promising directions for future exploration. By bridging fluid dynamics with nanoelectronics technologies, the issue encourages integration of concepts and fosters collaboration among researchers from diverse domains. Overall, this special issue aims to deepen scientific understanding and stimulate innovation in areas where micro- and nanoscale processes play a transformative role.

Purpose: This research aims to investigate the flow and heat transfer characteristics of a hybrid nanofluid comprising water, single-walled carbon nanotubes (SWCNTs) and multi-walled carbon nanotubes (MWCNTs) over a stretching sheet under the influence of a magnetic field. Design/Methodology/Approach: The study employs a mathematical model that accounts for factors such as variable viscosity, thermal radiation, a porous medium and heat generation/absorption. The governing partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs) using similarity transformations and then solved numerically using the bvp4c solver in MATLAB. Findings: The numerical results reveal that the velocity profile of the hybrid nanofluid is significantly enhanced by the presence of MWCNTs. Additionally, the temperature profile is influenced by parameters like the magnetic field, heat source/sink and Prandtl number. The Yamada-Ota (Y-O) model is found to have a more pronounced effect on heat transfer compared to the Xue model. Originality/Value: This study provides valuable insights into the behavior of hybrid nanofluids in complex flow scenarios. The findings can be applied to the design and optimization of various thermal systems, such as heat exchangers and cooling devices.

This study investigates the thermal analysis of couple stress fluid flow driven by peristaltic pumping, focusing on the impact of surface roughness and channel geometry on fluid flow behavior and thermal properties. The analytical model examines the heat transfer behavior of couple stress fluid flow across smooth and rough surfaces, quantifying flow characteristics such as axial velocity, pressure gradient, and skin friction. A parametric analysis is conducted to examine the effects of key parameters, including the Grashof number, heat source parameter, and couple stress parameter, on flow characteristics and thermal properties. This study reveals that surface roughness and channel geometry significantly affect fluid flow behavior, altering thermal properties such as temperature distribution, heat transfer rate, and entropy generation. The findings provide insight into optimizing fluid flow and thermal management in microfluidic devices and cooling channels, particularly by reducing resistance. Key output parameters for these enhancements include reduced entropy generation, improved axial velocity, optimized pressure distribution, and better heat transfer efficacy. This study provides a benchmark for future research exploring various geometries of channel obstructions, surface modulations, and rheological properties of fluids with diverse thermal boundary conditions. The results have significant implications for the development of efficient biomedical devices and industrial applications.