Enhanced thermal transport in porous-assisted thin film flow of tri-hybrid nanofluid with viscous dissipation: Implications for energy and cooling systems

The main aim of the present study is to explore Jeffrey nano-fluid flow over a linearity stretching isothermal sheet with thermal radiation. Numerous scientists have studied the flow past a stretching sheet for industrial applications such as metal spinning, plastic film sketching, glass blowing, and filament cooling. Viscous dissipation, magnetic field, and heat source impacts are also included. The governing system of non-dimensionless partial differential equations have been evaluated by the combination of local non-similarity technique into a collection of dimensionless nonlinear coupled differential equations with boundary conditions. The spectral Quasi-linearization method (SQLM) is used to solve the governing equations numerically. The effect of different physical parameters on the temperature, velocity, and concentration is depicted graphically and analyzed in detail. This study may be useful for understanding and optimizing the performance of non-Newtonian behavior for specific applications.

A quasi-static model for the normal impact of a viscous drop on a non-wetting substrate is developed. The axisymmetric deformation of a sessile drop is described analytically using new asymptotically exact approximations to solutions of the Young-Laplace equation. Viscous dissipation is accounted for in linearized form through a damping coefficient inversely proportional to the relaxation time of small-amplitude oscillations of a viscous sessile drop. This formulation enables evaluation of the key characteristics of Hertz-type impact at low Weber numbers, including the drop spreading factor, restitution coefficient, and characteristic time scale. Comparison with experimental data demonstrates that the model reliably captures the essential features of slow, viscously damped liquid drop impacts on non-wetting surfaces.

This article presents a unified numerical investigation of dual-phase thermal and concentration relaxation in magneto-viscoelastic Williamson nanofluid flow over a permeable, thermally radiating stretching sheet using the Cattaneo–Christov (C–C) flux framework. The governing magnetohydrodynamic boundary-layer equations, including Joule heating, viscous dissipation and thermal radiation, are reduced via similarity transformations to a coupled nonlinear ODE system and solved with a high-accuracy spectral quasilinearization method (SQLM). Residuals below 10 −12 are achieved within six iterations on 40 Chebyshev nodes, ensuring grid-independent convergence. Parametric analysis shows that thermal relaxation ( β T = 0.1) suppresses wall heat flux by about 15.2% and thickens the thermal boundary layer by 4.48% (1% thickness criterion), confirming finite-speed heat propagation beyond classical Fourier theory. Concentration relaxation ( β C = 0.1) intensifies nanoparticle gradients, elevating the Sherwood number by nearly 4%. Suction ( S = +0.5) contracts both momentum and thermal layers, enhancing the Nusselt number by roughly 22%, whereas injection reverses this trend. Increasing the velocity ratio parameter from A = 0.1 to 0.4 reduces the skin friction by 24.4%. Radiation and thermophoresis further expand the thermal layer, while a higher Prandtl number confines heat within a thinner region. This study shows that the C–C flux model outperforms the traditional Fourier and Fick laws in representing finite-speed relaxation effects, providing valuable guidance for improving thermal and mass transport in engineering designs, including high-efficiency heat exchangers, electromagnetic coating lines, polymer extrusion dies, solar thermal collectors, and precision biomedical drug-delivery systems. These findings provide a comprehensive benchmark for designing advanced nanofluid-based technologies where simultaneous control of heat and mass transport under electromagnetic fields is required.

Context. Ionisation controls the chemistry, thermal balance, and magnetic coupling in protoplanetary discs. However, standard ionisation vectors such as stellar UV, X-rays, Galactic cosmic rays might not be efficient enough, as UV/X-rays are attenuated rapidly with depth, while Galactic cosmic rays are modulated. Turbulence-induced magnetic reconnection in disc atmospheric layers offers a physically motivated, in situ source of energetic particles (EPs) that has never been considered. Aims. We quantify the ionisation and heating produced by EPs accelerated by turbulent reconnection, identify where they dominate over X-rays and Galactic cosmic rays, and determine energetic thresholds for their relevance. We provide scalable diagnostics tied to the local energy budget. Methods. We adopt a Fermi-like acceleration model with parameters linked to a turbulent reconnection geometry trigger by the magneto-rotational instability, yielding a steady-state energy distribution of the EP forming a power-law of index p = 2.5. We propagate electrons and protons through the disc and compute primary and secondary ionisation and associated heating on a fiducial T Tauri disc model background. The non-thermal normalisation is set by the fraction of local viscous accretion energy dissipation channelled to EPs, parametrised by κ . Results. For κ ≳ 0.4%, EPs ionisation overpass standard sources such as X-rays and Galactic cosmic rays in the disc atmosphere and intermediate/deep layers out to radii of a few tens of astronomical units. Even at κ ~ 0.025%, EPs contribute at the few-percent level, thus are chemically and dynamically relevant. The EP-induced heating complements UV/X-ray heating in the atmosphere and persists deeper. These results identify EPs accelerated by turbulence-induced magnetic reconnection as a rather robust, disc-internal ionisation channel that should be included in thermo-chemical and dynamical models of protoplanetary discs.

The increasing demand for integrated solutions that balance sound insulation with ventilation in modern green building designs has driven the development of innovative approaches. This study proposes compact three-dimensional hexa-protruded perforated plates with staggered layers. Compared to a traditional solid wall, the hexa-protruded perforated plates with staggered layers achieve a material cost reduction of ∼30.1% for an equivalent level of sound insulation performance improvement. In terms of sound propagation and attenuation, the improved insulation performance is driven by the synergistic interplay of reflection and absorption. In addition, viscous and thermal dissipation effects further synergistically enhance the attenuation within the structure. The validity of simulated transmission loss is corroborated by the experimental data. The hexa-protruded perforated plates with staggered layers can be a potential candidate for compact sound insulation materials that support ventilation.

Abstract A coupled system composed of a Newtonian fluid located on a sinusoidally forced elastic solid is studied analytically and numerically. The focus is on the transient evolution from the beginning of the forced oscillations and on the periodic behaviour established once the transient has vanished. The analytical solution is expressed as series summations that elucidate the propagation and reflections of elastic transverse waves through the solid layer and the viscous dissipation of oscillations in the fluid layer. Short-term transients in both the fluid and the solid form at every interaction between an elastic wave and a solid boundary. The long-term transient, quantified by the power balance in the fluid layer, instead pertains to the formation of all the elastic waves in the solid layer. The system can be viewed as a generalized transient Stokes layer generated by the elastic waves or as a damped resonant oscillator when the velocity at the fluid–solid interface increases significantly with respect to the forcing amplitude. A parametric study is carried out for three applications of technological interest, i.e. the indirect measurement of fluid viscosity, the turbulent drag reduction by travelling shear waves and the sensing and manipulation of biological flows.

Abstract The present study investigates the bio‐convective, electrically conductive flow of a Maxwell–Sutterby nanofluid through an exponentially stretching channel under the influence of viscous dissipation and an exponential heat source/sink. The primary novelty of this work lies in the analysis of activation energy and thermal characteristics of the system in the presence of thermophoretic diffusion and nonlinear radiation effects, incorporated within a revised mathematical framework based on boundary layer theory. The governing nonlinear partial differential equations are formulated using the boundary layer approximations. These equations are subsequently transformed into a dimensionless form through appropriate similarity transformations and solved employing the Runge–Kutta–Fehlberg (RKF45) method to ensure computational accuracy and reliability of the results. Graphical representations are presented to illustrate the influence of key parameters on the pertinent flow profiles, supplemented by numerical data. A convergence criterion is established to verify the precision of the proposed model parameters. The outcomes of this study provide valuable insights that may guide future experimental validation and contribute to the improved design of mechanical systems utilizing nanofluids for enhanced heat and mass transfer performance.

A hybrid numerical scheme for modeling viscous dissipation in aerostatic bearings with micro-hole restrictors: From CFD simulations to engineering-friendly loss coefficients

Global stability analysis on the onset of convection in an inclined porous layer with Casson fluid under the effect of viscous dissipation and along-slope buoyancy induced throughflow

The primary objective of the study is to inspect the variations in heat and mass transfer within a conductive, hydromagnetic flow exhibiting triple-diffusive characteristics. This research explores the influence of heat generation, Joule’s heating, and viscous dissipation by using the Boussinesq approximation on free convective MHD flow, examining the collective effect of Soret and Dufour phenomena. The study also took thermal and solutal stratification into consideration and handled in a unique way the impacts of varying electrical conductivity, variable thermal conductivity and variable viscosity. The altered system of partial differential equation is selected under the RK shooting technique for solution, and the transformation known as the Lie group is used to obtain symmetry reductions of that system. Graphical representation illustrates the impact of various factors, such as Lewis number, magnetic parameter, buoyancy ratio parameter, radiation parameters and Eckert, on all profiles. The results indicate that the magnetic field parameter undergoes a fall in the velocity profile in both fluid flow situations. Likewise, similar outcomes were seen in the salt concentration distributions as a result of variations in the buoyancy ratio factors. Increasing values of [Formula: see text] and [Formula: see text] cause a significant reduction in the skin friction coefficient, corresponding to less surface drag in fluid flow. The Nusselt number decreases with increasing [Formula: see text], indicating a decrease in heat transfer rate. With an increase in [Formula: see text] from 0.1 to 0.9, the Nusselt number drops around 83.33% when it comes to assisting flow. Under opposing flow, the Nusselt number declines by 50% as [Formula: see text] increases.

ABSTRACT The purpose of this study is to investigate the effects of nonlinear buoyancy and temperature‐dependent viscosity on mixed convection Couette flow in the presence of heat generation/absorption. A mathematical formulation based on the governing momentum and energy equations is developed, and the resulting nonlinear equations are solved using the homotopy perturbation method. The parametric analysis shows that both viscosity variation and nonlinear buoyancy significantly influence the velocity and temperature fields, particularly near the channel walls. An increase in viscous dissipation enhances the velocity near the heated wall, while an opposite behavior is observed near the cooled wall, and it also raises the temperature throughout the channel. Higher viscosity leads to increased velocity and temperature close to the heated wall but produces reverse trends near the cooled wall. Similarly, increasing the nonlinear buoyancy parameter accelerates the flow near the heated wall while inducing a reverse effect near the cooled wall, and it elevates the temperature across the channel. Moreover, increased viscous dissipation intensifies the shear stress at the heated wall while reducing it at the cooled wall. Both the mean temperature and the rate of heat transfer at the walls increase as the Prandtl number rises from that of mercury to air . The onset of reverse flow occurs when and noticed that, the increase in increases the reversal flow on the cooled wall.

This research presents a detailed analysis of unsteady two-dimensional magnetohydrodynamic (MHD) nanofluid flow in a squeezed geometry, addressing the combined effects of heat and mass transfer. The study uniquely incorporates the influence of viscous dissipation, radiation, and cross-diffusion within the flow between two parallel plates, where the lower plate remains fixed and the upper plate undergoes motion. This study is crucial for enhancing the design and optimization of advanced heat transfer systems, especially in industries where efficient thermal management and precise control over fluid dynamics are essential. To tackle the complex governing equations, the study employs a methodical approach, transforming these equations into dimensionless ordinary differential equations by applying suitable dimensionless transformations. The transformed equations are then solved using the optimal homotopy analysis method (OHAM). The validation of OHAM approach is performed by comparing the results with those from established literature, ensuring the reliability and accuracy of the obtained solutions. The research provides a comprehensive investigation into how various dimensionless parameters such as the Brownian motion parameter, radiation parameter, cross-diffusion effects, and chemical reaction rate that affect the flow characteristics, including velocity, temperature, and concentration profiles. These effects are depicted through detailed graphical representations. This paper also provides a detailed analysis of the Nusselt number, skin friction coefficient, and Sherwood number in tabular form, offering a comprehensive view of the system's behaviour. The heat transfer rate with the rise in Dufour number gets reduced by 5.26% in the nanofluid flow. The reduction in the temperature as well as velocity profile is obtained for the greater values of magnetic parameter.

Hydrogels often have poor mechanical properties due totheir highwater content and low polymer concentration, which limits their utilityin applications that require them to withstand applied forces. Inspiredby natural biopolymers such as collagen and actin, which form highlyextended fibrillar networks that stiffen biological tissues, we developeda modular strategy that utilizes self-assembling peptides to directthe formation of covalently polymerized diacetylene networks in hydrogels.By systematically tuning peptide sequences, we precisely controlledthe supramolecular organization and molecular orientation within theself-assembled nanofibers. This optimization enabled efficient topotacticpolymerization of diacetylene moieties within the self-assemblingpeptides. Peptide sequences that readily promoted polymerization formedhydrogels with superior viscoelastic properties. Incorporation ofthese diacetylene peptide amphiphiles (DA-PAs) into covalently cross-linkedpoly­(ethylene glycol) (PEG) hydrogels increased their mechanical stiffness200-fold, while increasing viscous dissipation over 1,000 times. Modifyingthe chemical structure of the PEG cross-linker tuned the interfacialinteractions between the covalent PEG and DA-PA networks, modulatingstiffness by almost an order of magnitude. Since the DA-PAs readilydissolve in water prior to polymerization, they can be incorporatedinto most hydrogel systems. Adding them to alginate hydrogels ledto an almost 20-fold increase in the hydrogel stiffness. This approach,merging peptide-driven supramolecular chemistry with precise covalentpolymerization, provides powerful and versatile pathways for fabricatingmechanically robust materials that offer new insights into how hierarchicalstructures can be used to improve hydrogel mechanics.

This study presents a comprehensive theoretical investigation of biofluid transport relevant to biomedical engineering applications, including drug delivery, thermal regulation, and microfluidic systems. The combined effects of peristaltic motion, cilia-induced flow, and electroosmosis on an Ag–Ta/blood hybrid nanofluid, modelled as a Casson fluid, are examined in an asymmetric channel. The model incorporates an inclined magnetic field, Hall current, buoyancy force, thermal radiation, Joule heating, viscous dissipation, heat generation, and nanoparticle shape effects. Under long-wavelength and low-Reynolds-number assumptions, the governing equations are solved analytically using the homotopy perturbation method. Results show that non-spherical nanoparticles significantly enhance heat transfer, with laminar shapes improving thermal performance by 13.01%. Cilia length, magnetic field inclination, and Joule heating strongly influence velocity and temperature distributions.

Purpose The growing demands for efficient cooling systems, lubrication and anti-friction properties motivate the investigation of advanced heat transfer in fluid dynamics. The purpose of this study is to investigate the convective flow of ternary hybrid nanofluids around a vertical cylinder, considering the effects of a porous medium, magnetic field, thermal radiation, viscous dissipation and Darcy–Forchheimer influence on heat transfer and fluid velocity. Design/methodology/approach Introduce the similarity transformations to reduce the system of governing partial differential equations (PDEs) to a system of nonlinear ordinary differential equations (ODEs), which are then converted into linear first-order ODEs. The bvp4c solver in MATLAB is used to crack the transformed ODEs and for the graphical illustrations. Findings The combined effects of radiation, Biot number and Eckert number significantly enhance the heat transfer capabilities of ternary hybrid nanofluids, achieving a 17.533% improvement over nanofluids alone. The effects of porosity, Darcy–Forchheimer influence and the magnetic field on fluid motion and skin friction are also investigated and presented in detail. This study has broad applications in cooling systems for power plants, as well as in anti-friction properties for transportation, automotive, precision machinery, robotics engineering and lubrication in rotating machinery, polymers and textile engineering. Originality/value From the literature survey, it is noted that the simultaneous effects of magnetic field, thermal radiation, viscous dissipation and convective boundary conditions on Darcy–Forchheimer flow of ternary hybrid nanofluids around a vertical cylinder have not been investigated so far, and this study addresses this gap. Further, the results are validated and compared with the existing results as a special case.

The present study examines the magnetohydrodynamic flow of a Casson fluid over a stretching sheet while accounting for homogeneous and heterogeneous chemical reactions. The model further incorporates Joule heating, viscous dissipation, nonlinear thermal convection, and radiative heat transfer relevant to moderately high temperatures. The resulting system of nonlinear ordinary differential equations is tackled numerically using the RKF-45 method combined with a shooting technique. The influence of key physical parameters on the velocity, temperature, and concentration fields is thoroughly analyzed through graphical and tabulated results. The findings indicate that increases in homogeneous and heterogeneous reaction parameters reduce species concentration and shrink the associated boundary layers, while stronger thermal radiation and higher temperature-ratio parameters elevate the fluid temperature.

The third-grade viscoelastic model, formulated within the Rivlin–Ericksen constitutive framework, offers a distinct advantage over other models by simultaneously capturing normal stress differences and shear-thinning behavior in nonlinear fluids. This work applies third-grade fluid model to investigate viscoelastic rotating flow with heat dissipation effects over a stretchable surface, highlighting the combined impact of rotation, viscous dissipation and entropy generation, which has not been addressed in prior studies. The involvement of third-grade fluid’s stresses generates nonsimilar terms in both momentum and heat transfer equations. Compared with the prior studies conducted for nonrotating frame, this work reports a locally nonsimilar analysis wherein the derivatives along the streamwise direction are retained. Irreversibility effects in the model are further scrutinized by evaluating entropy generation rate and its dependence on fluid’s rheological properties. A neural network framework trained with the Levenberg–Marquardt (LM) algorithm is also applied to predict entropy rates and Bejan number. Multiple validation metrics including regression plot (RP), mean squared error (MSE) and histograms are used to demonstrate the reliability of artificial neural network (ANN) based forecasts. The results obtained from the ANN closely align with those from the bvp4c method, exhibiting an exceptionally low mean absolute error. The flow fields and associated fluid dynamic characteristics are analyzed under varying rotation rates, elasticity parameters and shear-thinning effects. This study reveals that entropy generation intensifies near the wall when the temperature difference increases, primarily due to stronger thermal gradients. As viscous dissipation intensifies, more mechanical energy transforms into heat and the associated entropy generation rate becomes progressively higher.

During liquid drainage from intermediate vessels in various industrial processes such as continuous steel casting, aircraft fuel supply, and chemical separation, free-surface vortices commonly occur. The formation and evolution of these vortices not only entrain surface slag and gas, but also lead to deterioration of downstream product quality and abnormal equipment operation. The vortex evolution process exhibits notable three-dimensional unsteadiness, multi-scale turbulence, and dynamic gas–liquid interfacial changes, accompanied by strong coupling effects between temperature gradients and flow field structures. Traditional macroscopic numerical models show clear limitations in accurately capturing these complex physical mechanisms. To address these challenges, this study developed a mesoscopic numerical model for gas-liquid two-phase vortex flow based on the lattice Boltzmann method. The model systematically reveals the dynamic behavior during vortex evolution and the multi-field coupling mechanism with the temperature field while providing an in-depth analysis of how initial perturbation velocity regulates vortex intensity and stability. The results indicate that vortex evolution begins near the bottom drain outlet, with the tangential velocity distribution conforming to the theoretical Rankine vortex model. The vortex core velocity during the critical penetration stage is significantly higher than that during the initial depression stage. An increase in the initial perturbation velocity not only enhances vortex intensity and induces low-frequency oscillations of the vortex core but also markedly promotes the global convective heat transfer process. With regard to the temperature field, an increase in fluid temperature reduces the viscosity coefficient, thereby weakening viscous dissipation effects, which accelerates vortex development and prolongs drainage time. Meanwhile, the vortex structure—through the induction of Taylor vortices and a spiral pumping effect—drives shear mixing and radial thermal diffusion between fluid regions at different temperatures, leading to dynamic reconstruction and homogenization of the temperature field. The outcomes of this study not only provide a solid theoretical foundation for understanding the generation, evolution, and heat transfer mechanisms of vortices under industrial thermal conditions, but also offer clear engineering guidance for practical production-enabling optimized operational parameters to suppress vortices and enhance drainage efficiency.

Direct numerical simulations with multi-step chemistry were performed for one- and two-dimensional freely propagating laminar premixed flames of methane–air and hydrogen–air mixtures with a matching density ratio to isolate the effects of hydrodynamic instability while allowing for a variable effective Lewis number, with the methane (hydrogen) flame being thermodiffusively stable (unstable). Entropy diffusion and generation mechanisms were analysed based on contributions from heat conduction, viscous dissipation, mass diffusion, and chemical reactions. Across both flames, chemical reactions were identified as the dominant source of entropy generation, with viscous dissipation contributing negligibly compared to other mechanisms. Significant differences were found in the structure of entropy generation rates across both flames, with varying degrees of correlation with curvature. Stronger correlations were found between the irreversible entropy generation rates and the heat release rate in both flames, suggesting the former as a potential marker for thermodiffusive instability. Analysis of the entropy generation profiles at representative locations across a flame front further revealed possible origins of the entropy behaviour under thermodiffusively stable and unstable conditions.