Slender Surface Research Articles

Bio-convection with activation energy effect on mixed convective flow of liquid over a slendering surface for the inclusion of Hall current and dissipative heat

Bio-convection with activation energy effect on mixed convective flow of liquid over a slendering surface for the inclusion of Hall current and dissipative heat

Dynamic simulation of unsteady Casson–Carreau fluid flow considering temperature-dependent variable-properties and thermo-solutal mixed convection over flat and slendering sheets

The present investigation delves into the intricate interplay between surface effects and fluid dynamics, focusing on the flow characteristics of Casson and Carreau fluids endowed with temperature-dependent thermophysical properties. Specifically, the study explores the ramifications of radiative, mixed convection, and magnetized processes on heat and mass transfer phenomena. A comprehensive mathematical model is developed to analyze the behavior of Casson–Carreau fluids in conjunction with microscopic particles and gyrotactic microorganisms over both flat and slender surfaces. Leveraging similarity transformations, the governing equations are transformed into dimensionless form, facilitating numerical solutions using the bvp5c solver in MATLAB. The ensuing numerical and graphical analyses elucidate key physical quantities, including local skin friction coefficients, gyrotactic microorganism density, Nusselt number, and Sherwood number, across a spectrum of physical parameters. Notably, the investigation underscores the profound influence of flat surfaces on flow patterns and highlights the heightened consumption of fluid particles with increasing variable diffusivity and thermal conductivity. Moreover, enhanced values of parameters such as variable motile microorganism diffusion coefficient, Brownian motion parameter, and temperature-dependent thermal conductivity parameter are found to augment the Nusselt number, indicative of intensified heat transfer rates. This research underscores the imperative of comprehending the intricate dynamics of fluid flow and heat transfer, offering actionable insights for enhancing engineering designs and addressing multifaceted challenges across domains encompassing chemical engineering, environmental science, and biomedical applications.

The geopolitics of anti-Asian racism: A critical discourse analysis of dominant Western narratives on China in the COVID-19 era

Over the past decades, dominant Western institutions have increasingly perceived China as a challenge to a US-centric world order and framed it as a threat to Western values. We propose that understanding the synergies between these institutions’ messaging on China and the reported growing number of incidents of anti-Asian racism can illuminate what drives the latter, especially in the COVID-19 era. We draw from theories of globalization, political socialization, and stigma to identify dominant narratives on China during COVID-19 through a critical discourse analysis of public documents, spanning close to three years, from governments, civil society entities and actors influential in public policy, and Western mainstream media. We show that the dominant Western narrative is that China is a threat to Western values and to humanity, both perceived as interchangeable. This narrative is constructed through double standards and the omission of relevant geopolitical contexts that might help Western publics to develop a more nuanced perspective of China’s role in world affairs. The ideological work of “othering” China and whoever refuses to condemn it is all but inevitable, as is the message of “Us versus Them” with the potential to legitimize anti-Asian racist beliefs, attitudes, and behaviours. Discourse is not a slender surface of contact, or confrontation, between a reality and a language (langue) […] in analysing discourses, one sees the loosening of the embrace [between] words and things, and the emergence of a group of rules proper to discursive practice. These rules define not the dumb existence of a reality […] but the ordering of objects [performing] a work that […] displaces its own data, and reveals, at the end of the day, a quite different task. A task that consists of not - of no longer - treating discourses as groups of [signifiers] but as practices that systematically form the objects of which they speak. Of course, discourses are composed of signs; but what they do is more than use these signs to designate things. It is this more that renders them irreducible to the language (langue). It is this 'more' that we must reveal and describe. Michel Foucault, The Archeology of Knowledge, 1972, P. 48 & 49

Entropic behavior with activation energy in the dynamics of hyperbolic-tangent mixed-convective nanomaterial due to a vertical slendering surface

PurposeNonlinear mixed-convective entropy optimized the flow of hyperbolic-tangent nanofluid (HTN) with magnetohydrodynamics (MHD) process is considered over a vertical slendering surface. The impression of activation energy is incorporated in the modeling with the significance of nonlinear radiation, dissipative-function, heat generation/consumption connection and Joule heating. Research in this area has practical applications in the design of efficient heat exchangers, thermal management systems or nanomaterial-based devices.Design/methodology/approachSuitable set of variables is introduced to transform the PDEs (Partial differential equations) system into required ODEs (Ordinary differential equations) system. The transformed ODEs system is then solved numerically via finite difference method. Graphical artworks are made to predict the control of applicable transport parameters on surface entropy, Bejan number, Sherwood number, skin-friction, Nusselt number, temperature, velocity and concentration fields.FindingsIt is noticed from present numerical examination that Bejan number aggravates for improved estimations of concentration-difference parameter a_2, Eckert number E_c, thermal ratio parameter ?_w and radiation parameter R_d, whereas surface entropy condenses for flow performance index n, temperature-difference parameter a_1, thermodiffusion parameter N_t and mixed convection parameter ?. Sherwood number is enriched with the amplification of pedesis-motion parameter N_b, while opposite development is perceived for thermodiffusion parameter. Lastly, outcomes are matched with formerly published data to authenticate the present numerical investigation.Originality/valueTo the best of the authors' knowledge, no investigation has been reported yet that explains the entropic behavior with activation energy in the flowing of hyperbolic-tangent mixed-convective nanomaterial due to a vertical slendering surface.

Significance of nanoparticle shape factors on MHD nanofluid flow across a slender surface

ABSTRACT This research scrutinizes the significance of nanoparticle shapes over the magnetized flow of engine-oil-based Ti6Al4V nanoliquid across a surface of varied thickness under the action of Buongiorno slip effects. The transmuted dimensionless equations and edge restrictions are exercised using the bvp5c scheme. This research’s prime purpose is to enhance the thermal transmission rate due to the suspension of spherical- or laminar-shaped nanoparticles (SSNs) or (LSNs) into the base liquid. The computational outcomes for flow, energy, and concentration fields were explored via plots and numerical illustrations. Evidently, energy transmission efficiency is developed in SSNs as compared with LSNs. The Buongiorno slip and nonuniform heat source factors tend to enrich the Nusselt number. The shape factor of nanoparticles is significant in enhancing or diminishing the heat flow rate.

Significance of gyrotactic microorganisms on the MHD tangent hyperbolic nanofluid flow across an elastic slender surface: Numerical analysis

Abstract In the current study, we numerically analyze the significance of motile microbes on the magnetohydrodynamic steady convective streams of tangent hyperbolic (TH) nanofluid flow across an elastic nonlinearly stretching surface of an irregular thickness. The consequences of an external magnetic field, thermal radiation, and thermal conductivity are also examined on the TH nanofluid. The governing system of equations (nonlinear set of partial differential equations) is transfigured into a system of ordinary differential equations (ODEs) by using the similarity variable conversions. Furthermore, the reduced form of nonlinear ODEs is numerically computed through the parametric continuation method (PCM) using MATLAB software. The relative evaluation is carried out to authenticate the numerical outcomes. It has been observed that the energy field accelerates with the Rayleigh number, Weissenberg number, and Brownian motion. The mass propagation ratio improves with the effect of activation energy and decreases with the influence of chemical reactions. Furthermore, the motile microbes’ profile declined with the outcome of the Peclet and Lewis numbers. The skin friction increases up to 7.3% with various magnetic values ranging from 0.5 to 1.5. However, the energy transfer rate declines to 5.92%. The thermal radiation boosts the energy propagation rate and flow velocity by up to 11.23 and 8.17%, respectively.

Impact of Joule heating on magnetohydrodynamic dissipative flow above a slendering surface with thermophoresis and Brownian movement with slip/no-slip conditions

ABSTRACT Purpose Hybrid nanofluids meet the necessities of several technological and production industries. Owing to these ample applications, a numerical investigation is accomplished to examine the thermal transmission feature of magneto-hybrid nanofluid flow due to an extending surface of varied thickness with multiple slip effects. Design/methodology The arising system of Partial Differential equations (PDEs) are exercised by adopting suitable similarities to attain the non-dimensional Ordinary Differential equations (ODEs) and the solutions are obtained by implementing bvp5c built in MATLAB package. The energy equation is loaded with Brownian motion, thermophoresis and Joule heating effects. The implication of pertinent constraints upon the flow features is discussed graphically. Findings The outcomes imply that the energy transmission rate is considerably high in no-slip case as equated with the slip case. Further, the power-law index parameter effectively uplifts the thermal and concentration gradients in both the situations. Originality The prime motive of this research is to present the relative analysis of heat transmission of hybrid nanoliquid in two different situations, namely slip and no-slip cases.

Numerical Study of Unsteady Magnetohydrodynamics Flow and Heat Transfer of Hybrid Nanofluid Induced by a Slendering Surface with Suction and Injection Effects

Since the last two decades, most of the researchers have concentrated on the nanofluids boundary layer flow over a surface of even thickness or flat surface. This article deals with a mathematical model, which describe the hybrid nanofluid (SiO2–MoS2/water) flow over a slendering surface (surface of uneven thickness). The novelty is to study the effects of natural convection and porous medium. The analysis of heat transfer is also accomplished and for the same purpose, the viscous dissipation, heat source/sink, ohmic heating and thermal radiation effects are incorporated. The velocity slip and thermal slip boundary conditions with suction/injection effects are applied. Similarity transformations are utilized to change the prevailing PDEs to ODEs. Numerical investigation is performed to solve the equations. The MATLAB in built function “bvp4c solver” is employed for finding the solution. The velocity and temperature profile were found higher for the injection case in comparison to the suction. The effect of power law index parameter and unsteadiness parameter is to aid the flow velocity. The heat generation parameters, Eckert number and volume fraction of nanoparticles act to augment the flow temperature. For the suction and injection case, the radiation parameter has positive correlation with the heat transfer rate.

Motile micro-organism based trihybrid nanofluid flow with an application of magnetic effect across a slender stretching sheet: Numerical approach

The steady magnetohydrodynamic ternary hybrid nanofluid flow over a slender surface under the effects of activation energy, Hall current, chemical reactions, and a heat source has been reported. A numerical model is developed to increase the rate of energy transfer and boost the efficiency and outcome of heat energy dissemination for a diverse range of biological applications and commercial uses. The rheological properties and thermal conductivity of the base fluids are improved by framing an accurate combination of nanoparticles (NPs). The ternary hybrid nanofluid has been prepared, in the current analysis, by the dispersion of magnesium oxide, titanium dioxide (TiO2), and cobalt ferrite (CoFe2O4) NPs in the base fluid. The physical phenomena have been expressed in the form of a system of nonlinear PDEs, which are degraded to a dimensionless system of ODEs through the similarity replacement and numerically solved by employing the MATLAB software package bvp4c. The graphical and tabular results are estimated for velocity, mass, and energy curves vs distinct physical factors. It has been noticed that the variation in the magnetic effect enhances the energy profile while the increasing number of ternary nanocomposites (MgO, TiO2, and CoFe2O4) in water lowers the energy curve. Furthermore, the effect of both Lewis and Peclet numbers weakens the motile microbe’s profile.

Application of Exponential Temperature Dependent Viscosity Model for Fluid Flow over a Moving or Stationary Slender Surface

The problem of laminar flow around a moving thin needle or slender surface with free stream velocity is analyzed when viscosity is supposed to have an exponential temperature dependency. Additionally, the temperature dependence in thermal conductivity is retained. Consideration of variable viscosity and thermal conductivity makes the governing equations coupled and non-linear. A self-similar solution of the problem is achieved, which depends on a parameter θw, which is the quotient of wall and ambient temperatures. A comparison of present findings is made with those of inversely linear temperature-dependent viscosity and constant viscosity cases. The size of the needle plays an important part in enhancing thermal boundary layer thickness. The expressions of skin friction coefficient and local Nusselt number in case of exponential temperature dependent viscosity are just derived in this study. An important observation is that computational results are qualitatively like those noticed for the case of inversely linear temperature dependency.

Numerical study of motile microorganism in Williamson MHD nanofluid flow over an elastic slender surface of an irregular thickness

The energy transmission through bioconvective MHD Williamson nanofluid (NF) flow has been numerically computed over a slender stretching surface of irregular thickness in this analysis. The consequences of a uniform magnetic field, heat generation and absorption, chemical reaction, variable thermal conductivity and viscosity depending on temperature have been also considered. The scenario has been represented as a system of PDEs. By using the similarity substitutions, the system of PDEs is simplified to ODEs. The obtained set of first-order differential equations is then evaluated using the numerical methodology parametric continuation method (PCM). The results are compared for consistency and validity purposes with the bvp4c package and existing literature. It has been noticed that the velocity distribution reduces with the variation of magnetic field and buoyancy ratio factor, while boosts with the rising values of velocity power index and mixed convection constraint. Furthermore, the motile microorganism profile enhances with the influence of Rayleigh number, while declines with the action of Lewis number, Peclet number and mixed convection parameters.

Heat and mass transfer analysis of nonlinear mixed convective hybrid nanofluid flow with multiple slip boundary conditions

The current study focuses on the 3D nonlinear mixed convective boundary layer flow of micropolar hybrid nanofluid in the presence microorganism and multiple slip conditions across the slendering surface. The concentration and energy equations are developed in the occurrence of activation energy and joule heating effect. The aim of this research is to consider the Carbon nanotubes (CNTs) which are favored materials in the manufacture of electrochemical devices because of their mechanical and chemical stability, good thermal and electrical conductivities, physiochemical consistency, and featherweight. By keeping such extraordinary properties of carbon nanotubes in mind, we investigate the flow of hybrid nanofluid having MWCNT (multi-wall carbon nanotubes) and SWCNT (single-wall carbon nanotubes). Using an appropriate similarity variable, the flow model (PDEs) are converted into nonlinear ordinary differential equations. The bvp4c approach is utilized to tackle the coupled differential equations. The impact of emerging parameter on temperature distribution, velocity field, concentration distribution, and microorganism field are presented graphically. It is noted the stronger values of wall thickness parameter and Hartmann number produces retardation effect, as a result fluid velocity declines for both SWCNT (single-wall carbon nanotubes) and MWCNT (multi-wall carbon nanotubes) hybrid nanofluid. Furthermore, the transport rate of heat and mass improves by the higher values of φ 2 for both simple and hybrid nanofluid.

Impact of Joule heating and multiple slips on a Maxwell nanofluid flow past a slendering surface

This manuscript presents a study of three-dimensional magnetohydrodynamic Maxwell nanofluid flow across a slendering stretched surface with Joule heating. The impact of binary chemical reactions, heat generation, thermal radiation, and thermophoretic effect is also taken into consideration. The multiple slip boundary conditions are utilized at the boundary of the surface. The appropriate similarity variable is used to transfer the flow modeled equations into ODEs, which are numerically solved by the utilization of the MATLAB bvp4c algorithm. The involved parameter’s impact on the concentration, velocity, and temperature distribution are scrutinized with graphs. The transport rates (mass, heat) are also investigated using the same variables, with the results reported in tabulated form. It is seen that the fluid relaxation, magnetic, and wall thickness characteristics diminish the velocities of fluid. Further, the velocity, concentration, and temperature slip parameters reduce the velocities of fluid, temperature, and concentration distribution. The results are compared to existing studies and shown to be in dependable agreement.

Flow Analysis of Hybridized Nanomaterial Liquid Flow in the Existence of Multiple Slips and Hall Current Effect over a Slendering Stretching Surface

Carbon nanotubes (CNTs) are favored materials in the manufacture of electrochemical devices because of their mechanical and chemical stability, good thermal and electrical conductivities, physiochemical consistency, and featherweight. With such intriguing carbon nanotubes properties in mind, the current research aims to investigate the flow of hybridized nano liquid containing MWCNTs (multi-wall carbon nanotubes) and SWCNTs (single-wall carbon nanotubes) across a slendering surface in the presence of a gyrotactic-microorganism. The temperature and solutal energy equation are modified with the impact of the modified Fourier and Fick’s law, binary chemical reaction, viscous dissipation, and joule heating. The slip conditions are imposed on the surface boundaries. The flow equations are converted into ODEs by applying similarity variables. The bvp4c approach is applied to tackle the coupled and extremely nonlinear boundary value problem. The outputs are compared with the PCM (Parametric continuation method) to ensure that the results are accurate. The influence of involved characteristics on energy distribution, velocity profiles, concentration, and microorganism field are presented graphically. It is noted that the stronger values of the wall thickness parameter and the Hartmann number produce a retardation effect; as a result, the fluid velocity declines for MWCNT and SWCNT hybrid nano liquid. Furthermore, the transport of the mass and heat rate improves with a higher amount of both the hybrid and simple nanofluids. The amount of local skin friction and the motile density of microorganisms are discussed and tabulated. Furthermore, the findings are validated by comparing them to the published literature, which is a notable feature of the present results. In this aspect, venerable stability has been accomplished.

Significance of variability in magnetic field strength and heat source on the radiative-convective motion of sodium alginate-based nanofluid within a Darcy-Brinkman porous structure bounded vertically by an irregular slender surface

The dynamical behavior and thermal transportation feature of an enhanced MHD convective Casson bi-phasic flows of sodium alginate-based nanofluids are examined numerically in a Darcy-Brinkman medium bounded by a vertical elongating slender concave-shaped surface. The mathematical framework of the present flow model is developed properly by adopting the single-phase approach, whose solid phase is selected to be metallic or metallic oxide nanoparticles. Besides, the influence of thermal radiation is taken into consideration in the presence of an internal variable heat generation. A set of feasible similarity transformations are applied for the conversion of the governing PDEs into a nonlinear differential structure of coupled ODEs. An advanced differential quadrature algorithm is employed herein to acquire accurate numerical solutions for momentum and energy equations. For validating the obtained numerical findings, extensive comparison tests are carried out in this sense. The results of the current exploration show that the wall heat transfer rate and the frictional effect are strengthened with the loading of nanoparticles and weakened with the mounting values of the heat source parameters. However, the magnetic parameter exhibits a reverse trend concerning those engineering quantities. Statistically, the slope linear regression method (SLRM) proves that the aurum-sodium alginate nanofluid presents the higher frictional factor, whereas the copper oxide-sodium alginate is the more thermal performant nanofluid.

Impact of Brownian motion and thermophoresis on bioconvective flow of nanoliquids past a variable thickness surface with slip effects

PurposeThe purpose of this paper is to scrutinize the heat and mass transfer attributes of three-dimensional bio convective flow of nanofluid across a slendering surface with slip effects. The analysis is carried out subject to irregular heat sink/source, thermophoresis and Brownian motion of nanoparticles.Design/methodology/approachAt first, proper transmutations are pondered to metamorphose the basic flow equations as ODEs. The solution of these ODEs is procured by the consecutive application of Shooting and Runge-Kutta fourth order numerical procedures.FindingsThe usual flow fields along with density of motile microorganisms for sundry physical parameters are divulged via plots and scrutinized. Further, the authors analyzed the impact of same parameters on skin friction, heat and mass transfer coefficients and presented in tables. It is discovered that the variable heat sink/source parameters play a decisive role in nature of the heat and mass transfer rates. The density of motile microorganisms will improve if we add Al-Cu alloy particles in regular fluids instead of Al particles solely. A change in thermophoresis and Brownian motion parameters dominates heat and mass transfer performance.Originality/valueTo the best of the knowledge, no author made an attempt to investigate the flow of nanofluids over a variable thickness surface with bio-convection, Brownian motion and slip effects.

Chemical Reaction and Radiation Effects on Non-Newtonian Fluid Flow over a Stretching Sheet with Non-Uniform Thickness and Heat Source

The principle priority of this study is to inspect the performance of two dimensional chemically reacting non-Newtonian fluid bearing Soret, Dufour, thermal radiation, heat source and slip effects. The flow is prompted by a slendering surface with variable thickness. Casson and Williamson fluid models are incorporated in this discussion. Governing equations are evolved and converted into ordinary differential equations using similarity transformations. We adopted homotopy analysis method (HAM) to pick up the solutions. The graphical and tabular results for velocity, temperature, concentration, skin friction factor, local Nusselt number and Sherwood number are secured for both Casson and Williamson fluids. The correspondence between the acquired and previous results reveals that they are in good correlation. It is found that there is a significant increase in the thermal boundary layer thickness when the strength of the Dufour number is increased.

Unsteady Magnetohydrodynamic Flow Past a Slendering Stretching Surface with Thermophoresis and Brownian Motion

In this paper, we investigate the influence of non uniform heat source/sink and thermal radiation on magnetohydrodynamic flow past a slendering surface with the influence of thermophoresis and Brownian effects. The governing non-linear flow problem is solved numerically by the aid of RK based shooting method. Influence of dimensionless parameters on the velocity, temperature and concentration profiles are explored through graphical illustrations. Skin friction factor, Nusselt and Sherwood numbers are presented and discussed. Rising values of magnetic and thermophoresis parameters increase the thermal and concentration distributions. Boosting values of Brownian motion parameter enhance the Nusselt and Sherwood numbers.

Numerical study of interaction between jet with rudders on slender body at hypersonic condition

In this paper, a numerical study of the interaction between transverse cold jets on slender body in front of or between X-shape rudders with rudders in the oncoming free stream is presented. Firstly, the flow field at different jet conditions is simulated and analyzed. Then, the total force and moment amplification factors of the corresponding slender body with jet at different locations are analyzed and compared with those results of non-jet flow. Numerical results show that interactions take a great effect to the configuration of the flow field around rudders and the pressure distribution on slender surface. Moreover, the force and moment amplification changes regularly along with the location of jet nozzle.

3D Casson nanofluid flow over slendering surface in a suspension of gyrotactic microorganisms with Cattaneo-Christov heat flux

A mathematical model is proposed to execute the features of the non-uniform heat source or sink in the chemically reacting magnetohydrodynamic (MHD) Casson fluid across a slendering sheet in the presence of microorganisms and Cattaneo-Christov heat flux. Multiple slips (diffusion, thermal, and momentum slips) are applied in the modeling of the heat and mass transport processes. The Runge-Kutta based shooting method is used to find the solutions. Numerical simulation is carried out for various values of the physical constraints when the Casson index parameter is positive, negative, or infinite with the aid of plots. The coefficients of the skin factors, the local Nusselt number, and the Sherwood number are estimated for different parameters, and discussed for engineering interest. It is found that the gyrotactic microorganisms are greatly encouraged when the dimensionless parameters increase, especially when the Casson fluid parameter is negative. It is worth mentioning that the velocity profiles when the Casson fluid parameter is positive are higher than those when the Casson fluid parameter is negative or infinite, whereas the temperature and concentration fields show exactly opposite phenomena.