Stagnation Point Flow Of Nanofluid Research Articles

Regression analysis and features of negative activation energy for MHD nanofluid flow model: A comparative study

This article elucidates the impact of activation energy on magnetohydrodynamic (MHD) stagnation point nanofluid flow over a slippery surface in a porous regime with thermophoretic and Brownian diffusions. Negative activation energy is scarce in practice, but the impact of negative activation energy could not be neglected as it is noticed in chemical processes. The rate of some Arrhenius-compliant reactions is retarded by increasing the temperature and is therefore associated with negative activation energies, such as exothermic binding of urea or water. In some processes, the temperature dependence of the pressure-induced unfolding and the urea-induced unfolding of proteins at ambient pressure give negative activation energies. The present mathematical model is solved with successive linearization method (a spectral technique). A comparison of results is made for negative and positive values of activation energy. Apart from it, the quadratic multiple regression model is discussed briefly and explained with bar diagrams. It is observed that with rise in unsteadiness parameter from 0 to 1 (taking positive activation energy), skin friction and Sherwood number are increased by 9.36% and 19% respectively, and Nusselt number is decreased by 26%. However, for negative activation energy, 9.36% and 112% enhancement is observed in skin friction and Sherwood number, respectively.

Impact of suction with nanoparticles aggregation and joule heating on unsteady MHD stagnation point flow of nanofluids over horizontal cylinder

Significance of studyNanofluids with aggregation effects mediated by nanoparticles, like geothermal panels and crossflow heat exchangers, ignite new industrial interests. Polymer and conversion processes have transport phenomena in the stagnation zone that must be continuously improved to raise the process quality standard. Aim of studyHence, the current computational study examines a TiO2−C2H6O2 nanofluid's unsteady stagnation-point flow performance via a shrinking horizontal cylinder. In addition, the effects of a magnetic field, joule-heating viscous dissipation, nanoparticles aggregation and mass suction on the boundary layer flow are reflected. Methodology: The RK-IV with shooting method is applied to resolve the simplified mathematical model numerically in computing software MATHEMATICA. In certain circumstances, comparing the current and prior findings indicates good agreement with a relative error of around 0%. FindingsThe implementation of a heat transfer operation may be improved by increasing suction settings. Unsteadiness, nanoparticle volume fraction, magnetic, curvature, and Eckert number (implies the operating Joule heating and viscous dissipation) all influence heat transfer rate. The velocity and temperature profiles both increase as the unsteadiness, magnetic field, and nanoparticle volume fraction parameters increase, whereas the curvature and suction parameters show the opposite behavior. When the values of the suction parameters were changed from 2.0 to 2.5 with φ = 0.01, the heat transfer rates rose by 4.751%. A comparison shows that the model with aggregation has a better velocity profile, while the model without aggregation has a better temperature profile.

Unsteady mixed convective MHD boundary stagnation point nanofluid flow with multi-slip effects, variable wall temperature and porosity phenomenon

This research highlights the physical significance of nanoparticle in magnetohydrodynamics (MHD) stagnation point flow (SPF) over a stretchable surface with porosity effect and boundary slip phenomenon. The nanoliquid and its advanced thermal activity are shown extra auspicious results when the flow is considered over a permeable (porous) medium. In addition, the nanoparticles of radius size play an important role in the thermal performance of nanofluid. In this work, copper is accounted as a nanoparticle and water as a base fluid. Nanomanufacturing, surface engineering, coatings, nanofabrication and tribology are some of the important and special mechanical characteristics of nanoparticles [D. Guo, G. Xie and J. Luo, J. Phys. D, Appl. Phys. 47, 013001 (2014)]. The flow is electrically conducted in the presence of applied magnetic field. Mixed convection, Joule heating and viscous dissipation effects are accounted in the mathematical modeling. Appropriate similarity variables are used to convert the couple governing system of PDEs into ordinary ones and results are computed through bvp4c via shooting concept. From the obtained results, it is divulged that the velocity field increases against higher estimations of unsteady parameter, while it declines versus larger magnetic parameter and radius of nanoparticles. The engineering interest like skin friction and Nusselt number is mathematically calculated and results are computed in a tabular form, and their obtained outcomes show that the magnitude of skin friction rises against unsteadiness parameter and radius of nanoparticles. This study is an extended work of [Verma et al. Chem. Eng. J. Adv. 12, 100366 (2022)] with some extra flow assumptions like MHD, SPF, Joule heating, heat generation/absorption and viscous dissipation. Obtained results are compared with [Grubka and Bobba J. Heat Transf. 107, 248 (1985)], Verma et al. [Chem. Eng. J. Adv. 12, 100366 (2022)] and [Elbashbeshy and Emam Therm. Sci. 15, 477 (2011)] found 100% accuracy with them. The most important result of the conducted study is that the skin friction coefficient immensely augments subject to larger estimations of radius of nanoparticles when permeability of porosity is less.

Significance of entropy generation and nanoparticle aggregation on stagnation point flow of nanofluid over stretching sheet with inclined Lorentz force

It is well established that adding a certain number of nanoparticles to a nanofluid improves its thermal conductivity. The cause of this remarkable development is as of yet unidentified. Therefore, knowing the kinematics of nanoparticle aggregation is essential for determining the correct thermal impact of nanoscale particles. There are several potential technical and industrial uses for nanomaterials. From the perspective of these many application aspects, this paper examines the Al2O3-H2O nanofluid flow caused by a permeable stretching surface with the influence of an inclined Lorentz force and viscous dissipation. Entropy generation on nanofluid stagnation point flow with the influences of heat generation/absorption, nanoparticles aggregation with suction are also discussed in the current context. With and without nanoparticle aggregation, measurements of velocity, temperature, and entropy production are made. By applying the necessary transformations for heat and motion, ordinary differential equations may be derived from partial differential equations in certain circumstances. For the solution of ordinary differential equations, the Bvp4c technique is used. The effects of several dimensionless limitations on velocity, temperature, and entropy production, skin friction, and Nusselt number profiles are investigated, both when nanoparticle aggregation is present and when it is not. It is concluded that the velocity field is boosted for the velocity ratio and inclined Lorentz force parameters, while the temperature and entropy generation rise for the nanoparticle volume fraction, angle of inclination and Eckert number parameters. The rate of heat transmission improves as a result of the addition of ϕ and ε respectively. When the suction parameter of ε=0.5 is used for the aggregation model, it is claimed that there is an increase of roughly 13.2478% in the heat transfer rate. Temperature and entropy generation profiles for all pertinent parameters is higher for nanoparticles that have aggregated together as opposed to nanoparticles that have not aggregated together. This research was compared with previously published results to validate the findings, and great agreement was found.

A lubricated stagnation point flow of nanofluid with heat and mass transfer phenomenon: Significance to hydraulic systems

The improved thermal association of heat transfer is considerably observed due to interaction of nanoparticles in recent days. The lubrication phenomenon with heat and mass transfer effects plays a key role in the hydraulic systems. In current research, the thermal impact of nanofluid over a lubricated stretching surfaces near a stagnation point analytical has been studied. A thin layer of lubricating fluid with a variable thickness provides lubrication. The inspection of thermophoresis and Brownian motion phenomenon is illustrated via Boungrino model. The analytical finding of refurbished boundary layer ordinary differential equations is obtained by a reliable and proficient technique namely variational iteration method (VIM). The Lagrange Multiplier is a potent tool in proposed technique to reduce the computational work. In addition, a numerical comparison is presented to show the effectiveness of this study. The range of flow parameters is based on theoretical flow assumptions. Physical inspection of involved parameters on velocities, temperatures, concentrations, and other quantities of interest when lubrication is presented. The current results present applications in polymer process, manufacturing systems, heat transfer and hydraulic systems.

Heat transfer enhancement in stagnation point flow of nanofluid towards a linear stretching sheet with induced magnetic field: A Keller box strategy

Heat transfer enhancement in stagnation point flow of nanofluid towards a linear stretching sheet with induced magnetic field: A Keller box strategy

Significance of activation energy and entropy optimization in radiative stagnation point flow of nanofluid with cross-diffusion and viscous dissipation

The basic aim of this work is to examine the activation energy, thermal radiation, and the Joule heating influence in an incompressible two-dimensional dissipative stagnation point flow of a nano liquid past a curved stretching sheet. Furthermore, this work includes the investigation of entropy generation with cross-diffusion. The basic partial differential equations (PDEs) arising from the current study have been converted into ordinary differential equations (ODEs) by applying some dimensionless transformations. The solver bvp4c has been used for the numerical solutions of resulting ODEs. Various graphical results for the velocity, skin friction coefficient, temperature, Nusselt number, concentration, and Sherwood number have been plotted to show the impact of diverse values of the involved flow parameters. The skin friction coefficient is diminished by increasing the curvature and nanoparticles concentration whereas the heat transport rate reduces with the increase of Eckert and Hartmann number. Similarly, the escalating values of Soret number, chemical reaction rate parameter, and the temperature difference parameter enhance mass transportation. Furthermore, the Bejan number decreases with an increase in Brinkman and Hartmann number whereas the fluid’s entropy rises for the growing values of thermal radiation and temperature difference parameter.

Entropy Analysis of EMHD Hybrid Nanofluid Stagnation Point Flow over a Porous Stretching Sheet with Melting Heat Transfer in the Presence of Thermal Radiation

In this study, the entropy formation of an electromagnetohydrodynamic hybrid nanofluid at a stagnation point flow towards a stretched surface in the presence of melting heat transfer, second-order slip, porous medium, viscous dissipation and thermal radiation are investigated. Hybrid nanoparticles alumina (Al2O3) and copper (Cu) are considered, with the base fluid water (H2O). Similarity transformations are used to address the governing partial differential equations (PDEs) that lead to the corresponding ordinary differential equations. The resulting ODEs are solved by employing bvp4c solver numerically in the MATLAB package. The effects of temperature, transport, production of entropy and Bejan number Be are graphically exhibited. Higher radiation parameters R and an electric field E lead to an increase in fluid temperature. The velocity boundary layer is lowered by the magnetic field and porous media parameters. The opposite behaviour is observed in the electric field E. As a result, hybrid nanofluid has numerous uses in engineering cosmetics, automotive industry, home industry, for cancer treatment, food packaging, pharmaceuticals, fabrics, paper plastics, paints, ceramics, food colorants, electronics, heat exchangers, water purification, lubricants and soaps as well.

Nonlinear Thermal Diffusion and Radiative Stagnation Point Flow of Nanofluid with Viscous Dissipation and Slip Constrains: Keller Box Framework Applications to Micromachines

The radiated flow of magnetized viscous fluid subject to the viscous dissipation phenomenon is numerically studied. The radiative phenomenon is addressed with nonlinear relations. Further, analysis is performed by using the slip effects and convective thermal flow constraints. The transformed problem is numerically evaluated using the Keller Box method. The physical parameter effects, such as the magnetic parameter for the velocity profile, Prandtl number, Brownian motion parameter and Biot number for the energy profile and Lewis number, and the thermophoresis parameter for the concentration profile are discussed. The obtained results suggest applications in enhancing the heat transfer phenomenon, thermal system, energy generation, heat transmission devices, power generation, chemical reactions, etc.

MHD mixed convective stagnation point flow of nanofluid past a permeable stretching sheet with nanoparticles aggregation and thermal stratification

Using a thermally stratified water-based nanofluid and a permeable stretching sheet as a simulation environment, this research examines the impact of nanoparticle aggregation on MHD mixed convective stagnation point flow. Nanoparticle aggregation is studied using two modified models: the Krieger–Dougherty and the Maxwell–Bruggeman. The present problem's governing equations were transformed into a solvable mathematical model utilizing legitimate similarity transformations, and numerical solutions were then achieved using shooting with Runge–Kutta Fehlberg (RKF) technique in Mathematica. Equilibrium point flow toward permeable stretching surface is important for the extrusion process because it produces required heat and mass transfer patterns and identifies and clarifies fragmented flow phenomena using diagrams. Nanoparticle volume fraction was shown to have an impact on the solutions' existence range, as well. Alumina and copper nanofluids have better heat transfer properties than regular fluids. The skin friction coefficients and Nusselt number, velocity, temperature profiles for many values of the different parameters were obtained. In addition, the solutions were shown in graphs and tables, and they were explained in detail. A comparison of the current study's results with previous results for a specific instance is undertaken to verify the findings, and excellent agreement between them is observed.

Numerical analysis of concentration-dependent physical properties and bioconvection for Williamson nanofluid flow due to stretching/ shrinking sheet

In this paper, an investigation into Williamson nanofluid stagnation point flow of nano-biofilm over a stretching/ shrinking sheet with chemical reaction is performed. Moreover, the impact of cylindrical-shaped nanoparticles, activation energy, and bioconvection has been considered. The fluid’s fluctuating transport properties (dynamic viscosity, heat conductivity, nanoparticle mass diffusivity) and microorganism diffusivity are evaluated. The nonlinear systems of partial differential equations are transformed into nonlinear differential equations via the implementation of similarity transformations. The shooting approach and RK-4 technique are used for this investigation. The impacts of various fluid transport characteristics and various factors on patterns of velocity, temperature, the concentration of nanoparticles, and motile density are described. The Brownian motion, heat source and thermophoresis parameters all lead to a more consistent temperature profile being observed. It is seen that concentration-dependent properties decrease the velocity profile while the temperature, concentration, and motile density profiles increase. Also, the physical quantities decrease with the rising values of concentration-dependent properties.

Stagnation point flow of chemically reactive nanofluid due to the curved stretching surface with modified Fourier and Fick theories

With effective thermal performances and stability, the nanomaterials are intended to be the focus of investigators due to applications in energy systems, thermal extrusions, pharmaceutical processes, diagnoses and therapies, domestic refrigerators, bio-medical technologies, nuclear processes, antibacterial activities, etc. This research addresses thermal transport in stagnation point flow of nanofluid over a curved surface with nonlinear radiative effects and chemical reaction effects. Basic mass and momentum conservation laws are used to model the flow problem, whereas Cattaneo–Christov theories are used in thermal diffusion relations to model the heat and concentration equations. The similarity variables transformed the governing partial differential equations and the resulting equations are numerically simulated by the fourth-order finite difference scheme. The effective change in velocity, heat transfer rate, and mass fluctuation are reported due to effective values of parameters. It is noted that velocity, temperature, and concentration are affected by the curvature of the surface.

MHD stagnation point flow of nanofluid with SWCNT and MWCNT over a stretching surface driven by Arrhenius kinetics

MHD stagnation point flow of nanofluid with SWCNT and MWCNT over a stretching surface driven by Arrhenius kinetics

Dual solutions for MHD hybrid nanofluid stagnation point flow due to a radially shrinking disk with convective boundary condition

PurposeThis paper aims to study the stagnation point flow of Al2O3–Cu/H2O hybrid nanofluid over a radially shrinking disk with the imposition of the magnetic field, viscous-Ohmic dissipation and convective boundary condition.Design/methodology/approachSimilarity variables are introduced and used in reducing the governing partial differential equations into a system of ordinary differential equations. A built-in bvp4c solver in MATLAB is then used in the computation of the numerical solutions for equations (7) and (8) subject to the boundary conditions (9). Then, the behavior of the flow and thermal fields of the hybrid nanofluid, with various values of controlling parameters, are analyzed.FindingsThe steady flow problem resulted in multiple (dual) solutions. A stability analysis performed to identify the stable solution applicable in practice revealed that the first solution is stable while the second solution is unstable. The skin friction coefficient and Nusselt number of the hybrid nanofluid are found to be greater than the Al2O3–H2O nanofluid. Thus, the hybrid nanofluid has a better heat transfer performance than the nanofluid. Besides that, the presence of the magnetic field, suction, convective boundary condition and the enhancement of nanoparticle volume fraction of Cu augments the skin friction coefficient and Nusselt number of the hybrid nanofluid. Meanwhile, the presence of viscous-Ohmic dissipation reduces the heat transfer performance of the fluid.Originality/valueTo the best of the authors’ knowledge, the present results are original and new for the study of the flow and heat transfer of Al2O3–Cu/H2O hybrid nanofluid past a permeable radially shrinking disk. Considerable efforts have been directed toward the study of the boundary layer flow and heat transfer over stretching/shrinking surfaces and disks because of its numerous industrial applications, such as electronic, power, manufacturing, aerospace and transportation industries. Common heat transfer fluids such as water, alumina, cuprum and engine oil have limited heat transfer capabilities due to their low heat transfer properties. In contrast, metals have higher thermal conductivities than these fluids. Therefore, it is desirable to combine the two substances to produce a heat transfer medium that behaves like a fluid but has higher heat transfer properties.

Theoretical study of non-Newtonian micropolar nanofluid flow over an exponentially stretching surface with free stream velocity

The computational analysis of the second-order micropolar stagnation point flow of nanofluid over an exponentially permeable stretching sheet is considered. The freestream velocity with the thermal slip effects is taken into account in this analysis. This model is developed on the basis of flow assumptions and reduced into partial differential equations before applying the boundary layer approximations. The governing equations as a mathematical model are simplified with the help of suitable transformations. The differential system is further solved by using the bvp4c. Both graphs and tables are used to report observations. The skin friction and Nusselt number are reported for both weak and strong concentrations. The magnitude of skin friction is noticed greater for strong concentration in comparison with weak concentration. Subject to couple stress, the values of skin friction are relatively high for the case of weak concentration in comparison with strong concentration. Micropolar profile admit the direct relation toward micropolar parameter and micro-gyration parameter. Both Sherwood number and Nusselt number admits higher values for strong concentration as compared to weak concentration.

MHD heat and mass transfer stagnation point nanofluid flow along a stretching sheet influenced by thermal radiation

MHD heat and mass transfer stagnation point nanofluid flow along a stretching sheet influenced by thermal radiation

Hybrid nanofluid stagnation point flow past a slip shrinking Riga plate

Magnetic nanofluids cover many of uses since their characteristics are externally controllable, and their physical properties may vary with the nanoparticle volume fraction and magnetic field strength. Hybrid nanofluid also has been commercialized as the advancement of traditional nanofluid. The preliminary research on hybrid magnetic nanofluids inspired the present study to discover the stagnation-point flow of hybrid magnetite-cobalt ferrite/water nanofluid towards a shrinking Riga plate with the presence of velocity slip. The complex governing model of the flow is simplified by implementing the similarity transformation. A well-established numerical package, namely bvp4c in MATLAB, is used for numerical calculation as well as stability analysis. Two solutions are found due to the opposing flow from the shrinking Riga plate. From the stability analysis, the first solution which fulfills the boundary condition is the physically stable solution. The rising values of electromagnetohydrodynamic (EMHD) parameter and cobalt ferrite concentration augment the skin friction coefficient. Specifically, the critical point is lessened by 3% when the EMHD parameter is augmented from 0.3 to 0.5 and 0.5 to 0.7, which concludes that a suitably higher EMHD parameter could prevent the separation of the boundary layer. The heat transfer progress is actively performed with the enhancement of EMHD and velocity slip parameters which conclusively shows the suitability of these parameters in developing the cooling heat transfer fluid.

Numerical simulation for stagnation-point flow of nanofluid over a spiraling disk through porous media

A computational study on the diverging stagnation point of fluid flow is carried out over a convective plate. In this research, the unfaltering three-dimensional flow and heat transfer of non-Newtonian carbon nanotubes (CNTs) have been scrutinized. In order to analyze the stagnation point and rate of heat transfer, Xue’s model has been taken into consideration. Through similarity transformations, analytical unfolding of the governing coupled, non-linear, and ordinary differential equations has been performed. The most profoundly effective methods, termed the Keller Box method and the shooting method, are utilized. Using these propositions for CNTs of single-wall and multiwall carbon nano tubes, the results are co-related. For various values of material parameters, porosity, skin friction, temperature, solid volume fraction, Nusselt number, and Prandtl number, calculations have been put through. On observing, it is revealed that the porosity parameter has increased and both radial and azimuthal velocities decrease. When the stretching ratio parameter is increased while the azimuthal velocity is decreased, the radial velocity increases. It has also been discovered that sheer stress increases in direct proportion to porosity and stretching parameter. However, the rate of heat transfer shows inverse behavior against these parameters. The significant effects of these parameters are illustrated through graphs.

Transport properties of a hydromagnetic radiative stagnation point flow of a nanofluid across a stretching surface

The primary goal of this work seems to be to investigate the numerical results of the steady 2-D MHD stagnation point flow of an incompressible nanofluid along a stretching cylinder. This paper also investigates the effects of radiation and convective boundary conditions. Brownian motion and thermophoresis are included into the nanofluid model. Similarity transformations are used to modify the obtained momentum, energy, and nanoparticle volume fraction equations. The distributions of velocity, temperature, and nanoparticle fractions are all numerically computed using bvp5c inbuilt MATLAB tool. The diagrammatic representation of the effect of physical important flow fields on velocity, temperature, species concentration, heat transfer coefficient rates, and nanoparticle fraction. In this study as Bi and Nr increases the result in temperature profile and volume fraction of nanoparticles rises and the rate of heat transfer diminishes as Nb & Nt values enhances.

Thermal case study on linearly twisting cylinder: A radial stagnation point flow of nanofluid

The thermal case study is performed to inspect heat transfer aspects for radial stagnation point flow. For this phenomenon, the study assumes a linear twisting cylinder for the heated viscous nanofluid and the arrangement is investigated among the torsionally rotating cylinders and radial stagnation point flow. The dimensionless torsion rate σ , the volume fraction of nanoparticles φ and the Wangs Reynolds number R are three possible parameters that are articulated in the study. The BVP-Midrch routine integrated with the Maple software is used to obtain numerical results of the governing flow field equations. It is found that the axial wall stress f ″ ( 1 ) is a very weak function of σ , a weak function of φ and a strong function of R . Also, the azimuthal wall stress g ′ ( 1 ) is a strong function of R and shows a practically decreasing behavior and is linear with σ for the starting value g ′ ( 1 ) = 0 at σ = 0 . It is seen that the temperature gradient admits trifling variation for the positive iteration in torsional rate. Furthermore, the heat flux at surface admits direct relation towards volume fraction of nanoparticles.