Stretching Surface Research Articles

NON-SIMILAR MIXED CONVECTION ANALYSIS FOR MAGNETIC FLOW OF WILLIAMSON NANOFLUID OVER VERTICALLY STRETCHING SURFACE SUBJECTED TO VISCOUS DISSIPATION, POROUS MEDIA, AND HEAT SOURCE/SINK

The intention of this study is to explore the impact of non-similar modeling on mixed convective Williamson magnetized nanofluid flow over a vertically placed stretching surface with the consideration of engine oil as the base fluid and molybdenum disulfide (MoS<sub>2</sub>) as nanoparticles. The features of viscous dissipation, Darcy resistance, and heat source factor are also incorporated to examine the thermal prospective. The considered flow phenomenon is designated in the form of governing partial differential equations (PDEs) by employing the concepts of Boussinesq approximations and the boundary layer approach. By introducing non-similar transformations, the governing system is redesigned into dimensionless, non-similar, nonlinear PDEs. The dimensionless, non-similar framework is examined analytically by implementing local non-similarity and then stimulated numerically via bvp4c to explore the impacts of vital parameters on velocity and temperature distribution. The velocity distribution, temperature field, local Nusselt number, and drag force are elaborated through graphs and tables by altering the inputs of emerging parameters. The computations illustrate that the escalating inputs of the magnetic field and porosity parameter appear as the hindering factors against flow velocity. It is also discovered that with the rising estimations of nanoparticles, volume fraction leads an enhancement in the temperature distribution and decline in velocity profile. Furthermore, in a restricted case, the validity of results is found to be in good agreement with the published literature. A suitable range of stable solutions is obtained for emerging parameters. To the best of our knowledge, it is the first time that the non-similar analysis for the considered problem is reported. This work is anticipated to offer crucial data for the development of novel heat transfer devices in the future and serve as an incredible resource for the researchers studying nanofluid flows under various assumptions.

EFFECTS OF RADIATION AND CHEMICAL REACTION ON MHD CASSON NANOFLUID FLOW PAST A POROUS STRETCHING SURFACE

The present investigation aims to study the influence of thermal radiation and chemical reaction on the unsteady magnetized flow of Casson fluid with immersed nanoparticles. The flow is past a permeable stretching surface. The nanofluid heat transmission characteristics are described with the Buongiorno model. The governing system of non-linear partial differential equations (PDEs) is converted into non-linear ordinary differential equations (ODEs) with a similarity group of transformations. The reduced ODEs are numerically solved with an effective shooting strategy along with the standard R-K fourth-order method. The graphical illustration for the immerging parameters on non-dimensional velocity, temperature, and concentration is obtained through bvp4c using MATLAB. The code validation is provided by comparing the numerical outcomes of a few parameters with recently published work. The result shows that the thermal radiation boosts the energy supply in the flow field, and hence, the thermal regime enhances quickly. Due to the rise in chemical activity and Schmidt number, the concentration profile declines. The flow velocity declines with higher magnetic flux.

Analysis of tangent-hyperbolic rheological model considering nonlinear mixed convection, Joule heating and Soret-Dufour aspects from a stretchable convective stratified surface

Analysis of tangent-hyperbolic rheological model considering nonlinear mixed convection, Joule heating and Soret-Dufour aspects from a stretchable convective stratified surface

Stretchable superhydrophobic fluororubber fabricated by transferring mesh microstructures.

Stretchable flexible superhydrophobic surfaces are in great demand to achieve waterproofing performance in aerospace, electronic industry, and other fields. However, there are still many challenges in developing superhydrophobic surfaces, which maintain their wetting characteristics under high strain conditions with good tensile durability. Here, we propose a simple and efficient method to prepare a stretchable superhydrophobic fluororubber surface composed of hierarchical micro-convexities, which are orderly arranged and interconnected. Its peculiar structure shows excellent superhydrophobicity (155.48 ± 1.97°) and high water sliding angle due to Cassie's impregnating wetting regime. Due to the special structure and high mechanical strength of the surface, it can still maintain its superhydrophobic property after a variety of durability tests, including various stretching tests, sandpaper abrasion, sand impact, and high-temperature treatment. In addition, the surface can still realize the lossless transfer of water droplets even at large stretching strains, which is expected to be applied to microfluidic devices under extreme working conditions.

Modeling and simulation for Cattaneo-Christov heat analysis of entropy optimized hybrid nanomaterial flow.

Here, the hydromagnetic entropy optimized flow of a hybrid (Pb + Fe2O3/C2H6O2) nanoliquid by a curved stretchable surface is addressed. The Darcy-Forchheimer model is utilized for porous space. Lead (Pb) and ferric oxide (Fe2O3) are considered the nanoparticles and ethylene glycol (C2H6O2) as the base liquid. Thermal expression consists of dissipation and ohmic heating. Entropy generation is under consideration. The Cattaneo-Christov heat flux impact is discussed. Non-dimensional partial expressions by adequate transformations have been reduced to ordinary differential systems. The ND-solve technique is implemented for numerical solutions of dimensionless systems. Graphical illustrations of velocity, thermal field and entropy against influential variables for both nanoliquid (Pb/C2H6O2) and hybrid nanoliquid (Pb + Fe2O3/C2H6O2) are presented. Graphical illustrations of velocity, thermal field and entropy against sundry variables for both nanoliquid (Pb/C2H6O2) and hybrid nanoliquid (Pb + Fe2O3/C2H6O2) are presented. Influences of sundry variables on the Nusselt number and drag force for both nanoliquid (Pb/C2H6O2) and hybrid nanoliquid (Pb + Fe2O3/C2H6O2) are examined. A higher thermal relaxation time tends to intensify the heat transport rate and temperature. An increment in the magnetic variable leads to an enhancement of the entropy and thermal field. An improvement in liquid flow is seen for volume fraction variables. Velocity against the porosity variable and Forchheimer number is reduced. The Brinkman number leads to maximization of entropy generation.

Using Flexible and Stretchable Surface Electromyography Electrode Array to Evaluate Congenital Muscular Torticollis in Children.

Congenital Muscular Torticollis (CMT) is a neuromuscular disease in children, which leads to exacerbation of postural deformity and neck muscle dysfunction with age. Towards facilitating functional assessment of neuromuscular disease in children, topographic electromyography (EMG) maps enabled by flexible and stretchable surface EMG (sEMG) electrode arrays are used to evaluate the neck myoelectric activities in this study. Customed flexible and stretchable sEMG electrode arrays with 84 electrodes were utilized to record sEMG in all subjects during neck motion tasks. Clinical parameter assessments including the cervical range of motion (ROM), sonograms of the sternocleidomastoid (SCM), and corresponding histological analysis were also performed to evaluate the CMT. The muscle activation patterns of neck myoelectric activities between the CMT patients and the healthy subjects were asymmetric during different neck motion tasks. The CMT patients presented significantly lower values in spatial features of two-dimensional (2D) correlation coefficient, left/right energy ratio, and left/right energy difference (p < 0.001). The 2D correlation coefficient of activation patterns of neck rotation and extension in CMT patients significantly correlated with clinical parameter assessments (p < 0.05). The findings suggest that the spatial features of muscle activation patterns based on the sEMG electrode arrays can be utilized to evaluate the CMT. The flexible and stretchable sEMG electrode array is promising to facilitate the functional evaluation and treatment strategies for children with neuromuscular disease.

Thermal analysis of micropolar hybrid nanofluid inspired by 3D stretchable surface in porous media

The study of highly advanced hybrid nanofluids has aroused the interest of academics and engineers, particularly those working in the fields of chemical and applied thermal engineering.

Asymptotic Solutions of MHD Boundary Layer Equations leading the Flow of Viscous Fluid Due to a Stretching Surface

Asymptotic Solutions of MHD Boundary Layer Equations leading the Flow of Viscous Fluid Due to a Stretching Surface

MHD Nanoliquid Flow Along a Stretched Surface with Thermal Radiation and Chemical Reaction Effects

The consequences of viscous, ohmic, thermal radiation, and chemical reaction on an incompressible, steady, magnetized nanofluid moving through a stretched surface are investigated for choosing two distinct Nanoliquids (Cuo/water and Silver/water). Through the similarity transformations, the controlling dimensional equations of momentum, energy, and concentration were simplified to non-dimensional forms. The solution to the resulting problem is obtained by Bvp4c. The velocity, temperature and concentration are significantly shown for various emerging factors. On both kinds of nanofluids, thermal is grown consistently with an increasing Eckart number. It does, however, lessen as the radiation term values increase. Moreover, if the Schmidt number ranges on the concentration fluid flow indicate that the H(η) profile is going to fall. The tendency for H(η) to boost as the Soret number raises is becoming increasingly noticeable. Ag/water has a higher heat flow rate than Cuo/water when the amounts of Eckart and Radiation numbers are changed. Tables and plots displayed an engineering physical parameter such as coefficient of skin friction, rate of heat transmission and mass transfer.

Numerical Investigation of Suction/Injuction on Triple Diffusive MHD Casson Fluid Flow over a Vertical Stretching Surface

The article examines the characteristics of heat transfer for steady two-dimensional MHD Casson fluid with shear thickening properties in the presence of variable heat source for a vertical stretching sheet. The study considers the thermal radiation’s impact and velocity slip, and uses similarity transformations to convert the governing PDEs and corresponding boundary conditions into ODEs. Numerical solutions are obtained using shooting and R. K-4 methods, and the results presented for both injection and suction cases. The article examines the influence of various neutral parameters on the distribution of temperature, skin friction coefficient, velocity, and local Nusselt number, and presents the findings using tables and graphs. The study reveals that an increase in the Biot number and thermal radiation parameter results in an enhancement of the temperature distribution, while an increase in the suction/injection parameter causes a reduction in the velocity and temperature distributions for both injection and suction cases.

Influence of melting heat transfer and chemical reaction on the flow of non-Newtonian nanofluid with Brownian motion: Advancement in mechanical engineering

The aim of the present study is to investigate the melting heat and mass transport characteristics on the stagnation point flow of Powell–Eyring nanofluid over a stretchable surface because melting is so important in many processes, such as Permafrost melting, magma solidification, and thawing of frozen grounds, are all examples of soil melting and freezing around the heat exchanger coils of a ground-based pump. The developing mathematical model under the boundary layer flow in terms of differential equations is solved through a numerical algorithm using a boundary value problem solver bvp4c/shooting technique with the help of MATLAB software. The impact of emerging parameters on the velocity profile, temperature profile, and concentration profile is elaborated graphically. The profile and boundary-layer width rate for the value stretching parameter less than one rises when A enhances while the thickness of boundary layer velocity profile for the value stretching parameter greater than one decreases as A. The velocity function shows a decrement response for M, while the opposite behavior is seen against the concentration field. Furthermore, the numeric data for the friction factor and Nusselt number are demonstrated in tabular form, and the result shows a remarkable agreement with the previously published data.

Magnetohydrodynamics stagnation point flow and heat transfer over a non‐isothermal permeable shrinking sheet with variable surface temperature

AbstractThe present study is intended to analyse the effect of heat and mass transfer on boundary layer stagnation point flow of a viscous fluid over a non‐isothermal shrinking sheet subject to transverse magnetic field and variable surface temperature. The medium of flow is considered to be porous. Further, the effect of variable surface temperature and concentration are also taken care of in the present analysis. The governing partial differential equations (PDEs) are transformed into ordinary differential equations (ODEs) by suitable similarity transformations. The numerical simulation is carried out using Runge–Kutta method of fourth order with shooting technique. The physical significance of pertinent parameters of the flow phenomenon is studied with the help of graphs and tables. One striking outcome of the present analysis is that the unstable velocity profiles with inflection points are marked due to power law variation of temperature and concentration of the linearly stretchable bounding surface leaving aside the smooth fall in temperature and concentration (span wise) across the flow field. Further, it is noted that increase in magnetic field intensity, suction and thermal as well as mass buoyancy parameters enhance the skin friction concomitantly favouring the effective momentum transport.

Impression of nonlinear radiation and Stefan blowing on the magneto cross nano-Williamson fluid above exponentially stretching sheet

In order to investigate the impacts of mixed convection, electromagnetic force, and nonlinear thermal radiation on the nano-Williamson fluid (NWF) (Williamson fluid as a base fluid with nanoparticles) on an exponential stretched surface placed in a porous medium, this work considers the effects of both heat absorption-generation and Joule heating. However, consideration is also given to Stefan blowing in combination with Brownian motion and thermophoresis factors. By using similarity transformations and non-dimensional variables, the set of non-linear partial differential equations (PDEs) leading the study of fluid flow is converted into a system of ordinary differential equations (ODEs), which then numerically solved by the bvp4c built in MATLAB package. Additionally, the effects of the acquired relevant factors on the distributions of velocity, nanoparticles-concentration, and temperature have been investigated through graphical arrangements in order to give each parameter a physical meaning. The comparative values of skin friction and Nusselt number for dissimilar values of λ and S (Stefan blowing cases) are tabulated in Tables 1–4 respectively.

Hydrothermal and mass aspects of MHD non-Darcian convective flows of radiating thixotropic nanofluids nearby a horizontal stretchable surface: Passive control strategy

Numerous rheological examinations attested that many products employed frequently in our daily life exhibit a thixotropic rheological behavior with a shear-thinning tendency (e.g., toothpaste, hair gels, ketchup, gypsum, and paints). Motivated by the importance of nanofluids in the thermal and mass transfer processes and their rheological trends, this article aimed to analyze convective boundary layer flows of radiating thixotropic nanofluids over a horizontal stretching surface by considering the retardational influences of Darcy-Forchheimer and Lorentz forces and invoking the effective contribution of Brownian and thermophoresis diffusions in the energy and concentration equations. By adopting the boundary layer approximations along with the zero mass flux and convective conditions, the conservation equations of the present non-homogeneous nanofluid flow model are derived mathematically in the form of partial differential equations (PDEs) based on Buongiorno's approach. After converting the leading PDEs into a set of nonlinear coupled ordinary differential equations (ODEs) via feasible local similarity alterations, the resulting highly nonlinear system of governing ODEs is then solved numerically using an efficient differential quadrature algorithm. As findings, it is found that the thixotropy feature reinforces the nanofluid motion. Besides, the significant impact of the radiative term is noticed in the heat flux rate. In contrast, the induced Darcy-Forchhemier and Lorentz forces impact unfavorably on the nanofluid flow and consequently alter the intensity of drag forces. Further results are provided also graphically and tabularly.

Effect of Coriolis and buoyancy forces on three-dimensional flow of chemically reactive tangent hyperbolic fluid subject to variable viscosity

Thermophoresis effect has wide range of applications in electro-static precipitators and in biology for calculating single biological macro molecules, such as genomic-length DNA and HIV virus in the micro channels. Current study deal with effects of Coriolis and buoyancy forces on the three-dimensional boundary layer flow of tangent hyperbolic fluid with thermo-migration and haphazard motion of nano-sized particles. Arrhenius kind of chemical reaction is taken along an exponentially stretchable surface. The main focus of current exploration is to execute shear thinning nano-liquid flow past an exponentially rotating stretchable surface under the influence of variable viscosity, mixed convection and activation energy. We are motivated to explore the features of three-dimensional shear thinning model combined under the features of mixed convention, variable viscosity, and activation energy. The mathematical model is designed to generate PDEs and converted them into ODEs by employing fractious transformation. The numerical outcomes are exhibited via graphs by employing Bvp4c numerical technique whereas the values of skin friction coefficient are calculated by monopolizing shooting method. Characteristics of the parameters appearing in modeling like the viscosity parameter, power-law index, local Weissenberg number, mix convection parameter, rotation parameter, Prandtl number and chemical reaction parameter are comprehensively analyzed through graphical behavior. The impact of governing parameters on skin friction, heat and mass transfer rates is illustrated through tables. The detail analysis anticipates that the elevation in Weissenberg number and porosity caused decline in velocity. Further, the temperature behaves doppositely analogous to development Prandtl besides the thermophoresis parameter.

Analysis of Nonlinear Convection-Radiation in Chemically Reactive Oldroyd-B Nanoliquid Configured by a Stretching Surface with Robin Conditions: Applications in Nano-Coating Manufacturing.

Motivated by emerging high-temperature manufacturing processes deploying nano-polymeric coatings, the present study investigates nonlinear thermally radiative Oldroyd-B viscoelastic nanoliquid stagnant-point flow from a heated vertical stretching permeable surface. Robin (mixed derivative) conditions were utilized in order to better represent coating fabrication conditions. The nanoliquid analysis was based on Buongiorno's two-component model, which features Brownian movement and thermophoretic attributes. Nonlinear buoyancy force and thermal radiation formulations are included. Chemical reactions (constructive and destructive) were also considered since coating synthesis often features reactive transport phenomena. An ordinary differential equation model was derived from the primitive partial differential boundary value problem using a similarity approach. The analytical solutions were achieved by employing a homotopy analysis scheme. The influence of the emerging dimensionless quantities on the transport characteristics was comprehensively explained using appropriate data. The obtained analytical outcomes were compared with the literature and good correlation was achieved. The computations show that the velocity profile was diminished with an increasing relaxation parameter, whereas it was enhanced when the retardation parameter was increased. A larger thermophoresis parameter induces an increase in temperature and concentration. The heat and mass transfer rates at the wall were increased with incremental increases in the temperature ratio and first order chemical reaction parameters, whereas contrary effects were observed for larger thermophoresis, fluid relaxation and Brownian motion parameters. The simulations can be applied to the stagnated nano-polymeric coating of micromachines, robotic components and sensors.

Irreversibility analysis in the hydrothermal flow of γAl2O3/H2O and γAl2O3/C2H6O2 over a permeable stretching surface with effective Prandtl number

This present article provides a mathematical model that unravels the effect of entropy production on the hydrothermal behavior and cooling/heating process on the hybrid nanofluid spraying on a vertical permeable stretched surface. γAl2O3 is considered as the nanoparticles while water and Ethylene Glycol served as the base fluids. The derived heat balance equation considers the viscous dissipation phenomenon in addition to the effective Prandtl number. The competence of γAl2O3/H2O hybrid nanofluid on the cooling process as compared to γAl2O3/C2H6O2 nanofluid is deliberated in detail. These combined effects are commonly employed in solar film collectors, heat exchanger technologies, and geothermal energy storage systems. Using sufficient similarity, the fundamental equations are converted into dimensionless forms and solved using the spectral collocation method. The residual errors are graphed to analyze the method’s speedy convergence. Results for the embedded parameter on the flow speed, thermal distribution, entropy production, and Bejan number are shown graphically in the presence of an effective Prandtl number while the plots for skin friction and Nusselt number are displayed with and without an effective Prandtl number. As the Reynolds number parameters are increased, the Bejan number decreases, resulting in the dominance of entropy formation owing to frictional heating and magnetic field irreversibility.

High-performance flexible and stretchable self-powered surface engineered PDMS-TiO2 nanocomposite based humidity sensors driven by triboelectric nanogenerator with full sensing range

Harvesting electrical charge using triboelectrification provides a promising path to realizing uninterrupted self-powered sensors with application in wearable electronics and personal healthcare. This paper reports a high-performance flexible and stretchable self-powered humidity sensor based on triboelectric nanogenerators (TENG) that provides extreme responsivity, excellent repeatability with fast recovery time, and high selectivity. The device relies on a surface-engineered titanium oxide nanoparticle-silicone nanocomposite that generates triboelectric charge density strongly dependent on ambient humidity. The performance of the nanoengineered humidity sensor was systematically investigated at different humidity levels, which exhibits high responsivity (90% change for 75% RH change), a fast response time (1 s for 50% RH), a fast recovery time (3 s for 50% RH), and nearly full sensing range (0–99%). When activated by vertical contact separation at 2 Hz, the device generates a power density as high as 90 mW.m−2 and an open-circuit voltage of 50 V. An analytical model is derived to understand the underlying mechanism. The theoretical data explain the role of dielectric permittivity and surface area on the device operation, and the results are in good agreement with the experiments. The excellent combination of the properties suggests that these flexible TENGs can serve as reliable self-powered motion-driven humidity sensor.

MHD Non-Aligned Stagnation-Point Flow of Nanofluid over a Stretching Surface with a Convective Boundary Condition

In the present paper, MHD non-aligned stagnation-point flow has been found to be interesting and innovative in the analysis of viscous nanofluids over a stretching surface with a convective boundary condition in presence of the porous medium. Due to its many engineering and industrial uses, such as cooling nuclear reactors during an emergency shutdown, soft sheet extrusion, metal spinning, and solar central receivers exposed to wind current, the study of oblique stagnation point flow is important. The suitable similarity transformation is utilized for the reduction of a set of governing equations, which are solved by using the Differential Transformation Method (DTM) with Maple software. The Nusselt number (Nux), skin friction (Cf), and Sherwood number (Shx) are tabulated. A strong agreement is seen, and the accuracy of the results tabulated using DTM and the numerical method (fourth-order Runge-Kutta-Fehlberg integration scheme) is illustrated. Further, velocity, temperature, and nanoparticle volume fraction profiles are shown graphically and studied various parameters. It is reported that the magnetic parameter reduces the axial and oblique velocity gradients while enhancing the temperature and volume fraction profiles. The porosity parameter reduces the axial and oblique velocity gradients while enhancing the temperature profile.

Thermal Analysis of Radiative Darcy–Forchheimer Nanofluid Flow Across an Inclined Stretching Surface

Nanofluids have unique features that make them potentially valuable in a variety of medicinal, technical, and industrial sectors. The widespread applications of nanotechnology in modern science have prompted researchers to study nanofluid models from different perspectives. The objective of the current research is to study the flow of non-Newtonian nanofluid over an inclined stretching surface immersed in porous media by employing the Darcy-Forchheimer model. Both titanium oxide (TiO2) and aluminum oxide (Al2O3) are nanoparticles which can be found in blood (based fluid). The consequences of viscous dissipation, thermal radiations, and heat generation are also incorporated. Boundary layer approximations are employed to model the governing system of partial differential equations (PDEs). The governing PDEs with their associated boundary conditions are further altered to a dimensionless form by employing appropriate transformations. The results of the transformed model are collected using local non-similarity approach up to the second level of truncation in association with the built-in finite difference code in MATLAB (bvp4c). Additionally, the impacts of emerging factors on the fluid flow and thermal transport features of the considered flow problem are displayed and analyzed in graphical forms after achieving good agreement between accomplished computational results and published ones. Numerical variations in drag coefficient and Nusselt number are elaborated through the tables. It has been perceived that the enhancement in Casson fluid parameter diminishes the velocity profile. Moreover, it is noted that the porosity parameter and Lorentz's forces reinforce the resulting frictional factor at the inclined stretching surface.