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 nanopolymeric coatings, the present communication studies nonlinear thermally radiative OldroydB viscoelastic nanoliquid stagnant-point flow from a heated vertical stretching permeable surface. Robin (mixed derivative) conditions are utilized to better represent coating fabrication conditions. The nanoliquid analysis is based on Buongiorno's two-component model which elaborates Brownian movement and thermophoretic attributes. Nonlinear buoyancy force and thermal radiation formulations are included. Chemical reaction (constructive and destructive) is also considered since coating synthesis often features reactive transport phenomena. Via a similarity approach, an ordinary differential equation model is derived from the primitive partial differential boundary value problem. Analytical solutions are achieved employing homotopy analysis scheme. The influence of emerging dimensionless quantities on transport characteristics is comprehensively elaborated with appropriate data. The obtained analytical outcomes are compared with available limiting studies and good correlation is achieved. The computations show that the velocity profile is diminished with increasing relaxation parameter whereas it is enhanced when retardation parameter is increased. Larger thermophoresis parameter induces temperature and concentration enhancement. The heat and mass transfer rates at the wall are increased with an increment in temperature ratio and first order chemical reaction parameters while contrary effects are observed for larger thermophoresis, fluid relaxation and Brownian motion parameters. The simulations find applications in stagnation nano-polymeric coating of micromachines, robotic components and sensor

Stagnation point flow with thermal and magnetic field over a stretching sheet

The purpose of this research is to examine effects of thermal radiation and magnetic field on 2D stagnation point flow toward a stretching sheet. The governing equations are transformed into a system of nonlinear ordinary differential equations by similarities transformation method and then, solved, numerically using implicit finite difference scheme. The Velocity profile increase for higher values of stagnation point parameter, opposite occurred with magnetic field. The temperature profile is an increasing function of radiative energy

Cattaneo-Christov heat flux model for second grade nanofluid flow with Hall effect through entropy generation over stretchable rotating disk

The second grade nanofluid flow with Cattaneo-Christov heat flux model by a stretching disk is examined in this paper. The nanofluid flow is characterized with Hall current, Brownian motion and thermophoresis influences. Entropy optimization with nonlinear thermal radiation, Joule heating and heat absorption/generation is also presented. The convergence of an analytical approach (HAM) is shown. Variation in the nanofluid flow profiles (velocities, thermal, concentration, total entropy, Bejan number) via influential parameters and number are also presented. Radial velocity, axial velocity and total entropy are enhanced with the Weissenberg number. Axial velocity, tangential velocity and Bejan number are heightened with the Hall parameter. The total entropy profile is enhanced with the Brinkman number, diffusion parameter, magnetic parameter and temperature difference. The Bejan number profile is heightened with the diffusion parameter and temperature difference. Arithmetical values of physical quantities are illustrated in Tables

Numerical studies of nanofluid boundary layer flows using spectral methods.

Doctoral Degree. University of KwaZulu-Natal, PietermaritzburgThis thesis is focused on numerical studies of heat and mass transport processes that occur in nanofluid boundary layer flows. We investigate heat and mass transfer mechanisms in the flow of a micropolar nanofluid above a stretching sheet, the squeezed nanofluid flow between two parallel plates and the impact of activation energy and binary chemical reaction on nanofluid flow past a rotating disk. We present an analysis of entropy generation in nanofluid flow past a rotating disk and nanofluid flow past a stretching surface under the influence of an inclined magnetic field. This study aims to numerically determine to a high degree of accuracy, how nanoparticles can be utilized to alter heat and transport properties of base fluids in order to enhance or achieve desirable properties for thermal systems. The heat and mass transfer processes that feature in nanofluid boundary layer flow are described by complex nonlinear transport equations which are difficult to solve. Because of the complex nature of the constitutive equations describing the flow of nanofluids, finding analytic solutions has often proved intractable. In this study, the model equations are solved using the spectral quasilinearization method. This method is relatively recent and has not been adequately utilized by researchers in solving related problems. The accuracy and reliability of the method are tested through convergence error and residual error analyses. The accuracy is further tested through a comparison of results for limiting cases with those in the literature. The results confirm the spectral quasilinearization method as being accurate, efficient, rapidly convergent and suited for solving boundary value problems. In addition, among other findings, we show that nanofluid concentration enhances heat and mass transfer rates while the magnetic field reduces the velocity distribution. The fluid flows considered in this study have significant applications in science, engineering and technology. The findings will contribute to expanding the existing knowledge on nanofluid flow

Stability analysis and multiple solution of Cu–Al2O3/H2O nanofluid contains hybrid nanomaterials over a shrinking surface in the presence of viscous dissipation

Researchers are using different types of nanomaterials for the enhancement of the thermal performance of regular fluids such as water, kerosene oil, etc. However, these days, the researchers are more interested in hybrid nanomaterials. The purpose of this communication is to examine the stability analysis of Cu-Al2O3/water hybrid nanofluid over a non-linear shrinking sheet. The hybrid nanomaterials are composed of Cu and Al2O3. These hybridized nanomaterials are then dissolved in water taken as base fluid to form Cu-Al2O3//water hybrid nanofluid. Mathematical analysis and modeling have been attended in the presence of viscous dissipation and suction/injection effects. The governing equations of mathematical models are transformed into self-similar solutions in the form of ODEs by using similarity transformation. Solutions of the non-linear ODEs are created by employing of three-stage Lobatto IIIa formula which is built-in BVP4C function in the MATLAB software. A comparison of the current study has been done with the preceding published literature. The distributions of velocity, temperature profiles, coefficient of skin friction and heat transfer rate are presented graphically and conferred for numerous significant parameters entering into the problem. Results revealed the existence of dual solutions for a certain range of the suction/blowing parameter. Stability analysis is also done in order to obtain dual solutions stability. The smallest eigenvalues suggest that the first solution is stable from the second solution. Hybrid nanomaterials have a high scope toward nurturing our day-to-day life

Computational analysis of radiative heat transfer due to rotating tube in parabolic trough solar collectors with Darcy Forchheimer porous medium

This attempt numerically investigates the heat transfer in parabolic trough solar collectors due to the rotating tube for the hybrid nanofluid flow over the Riga surface with Darcy Forchheimer’s porous medium under the effect of solar radiation. The influences of viscous dissipation and Joule heating are also considered. Equations governing the fluid flow are non-dimensionalized by implementing appropriate similarity variables. The resulting non-dimensionalized ordinary differential equations are solved using the shooting technique with Adam Bashforth and Adam Moulten’s fourth-order numerical approach. The numerical outcomes for various influential physical parameters regarding the fluid velocity, temperature, Nusselt number, and entropy generation are presented in graphical form. It is observed that the thermal profile escalates with the higher values of Reynold’s number, modified magnetic field parameter, and Prandtl number. Also, the Nusselt number diminishes with augmenting values of the Eckert number, modified magnetic field parameter, Forchheimer number, and Darcy number. The optimization of heat transfer in parabolic trough collectors is essential to improve the performance of solar collectors. The concentrated solar power technology is adequate for storing radiation energy in higher amounts.Author U.F.-G. appreciates the support of the Government of the Basque Country, Grant N. ELKARTEK 22/85 and ELKARTEK 21/10. The research is supported by Researchers Supporting Project number (RSP2023R158), King Saud University, Riyadh, Saudi Arabia

Recent Trends in Coatings and Thin Film–Modeling and Application

Over the past four decades, there has been increased attention given to the research of fluid mechanics due to its wide application in industry and phycology. Major advances in the modeling of key topics such Newtonian and non-Newtonian fluids and thin film flows have been made and finally published in the Special Issue of coatings. This is an attempt to edit the Special Issue into a book. Although this book is not a formal textbook, it will definitely be useful for university teachers, research students, industrial researchers and in overcoming the difficulties occurring in the said topic, while dealing with the nonlinear governing equations. For such types of equations, it is often more difficult to find an analytical solution or even a numerical one. This book has successfully handled this challenging job with the latest techniques. In addition, the findings of the simulation are logically realistic and meet the standard of sufficient scientific value

Thermal performance of Oldroyd-B hybrid nanofluid in solar energy-based water pumping systems and entropy generation minimization

The growing need for reliable energy supply to enhance productivity in industrial and residential sectors underscores the importance of conserving solar energy. This can be achieved through measures such as optimizing solar collector coatings and optical heat processes. The environmental risks posed by fossil fuels, like coal and diesel, for electricity generation, further highlight the urgency of seeking alternative solutions. Solar energy has emerged as a highly promising option, capturing global attention for its potential to improve productivity and sustainability. The study focuses on examining aluminum alloy-titanium alloy/ethylene glycol hybrid nanofluid in the flow of non-Newtonian Oldroyd-B through a parabolic trough surface collector located in the solar water pumps (SWP). The Galerkin weighted residual method was utilized to solve the group of equations that describe momentum, energy, and entropy generation. The findings show that the hybrid nanofluid leads to better thermal radiative performance compared to the ordinary nanofluid. Therefore, the implications of these findings are substantial, particularly in the fields of thermal engineering and renewable energy. By offering insights into the efficient utilization of solar energy in water pumping systems and the reduction of entropy generation, this research has the potential to drive innovations that enhance the sustainability and performance of such systems. © 2023 The Author(s

A numerical study of entropy generation in nanofluid flow in different flow geometries.

This thesis is concerned with the mathematical modelling and numerical solution of equations for boundary layer flows in different geometries with convective and slip boundary conditions. We investigate entropy generation, heat and mass transport mechanisms in non-Newtonian fluids by determining the influence of important physical and chemical parameters on nanofluid flows in various flow geometries, namely, an Oldroyd-B nanofluid flow past a Riga plate; the combined thermal radiation and magnetic field effects on entropy generation in unsteady fluid flow in an inclined cylinder; the impact of irreversibility ratio and entropy generation on a three-dimensional Oldroyd-B fluid flow along a bidirectional stretching surface; entropy generation in a double-diffusive convective nanofluid flow in the stagnation region of a spinning sphere with viscous dissipation and a study of the fluid velocity, heat and mass transfer in an unsteady nanofluid flow past parallel porous plates. We assumed that the nanofluids are electrically conducting and that the velocity slip and shear stress at the boundary have a linear relationship. We also consider different boundary conditions for all the flow models. The study further analyzes and quantifies the influence of each source of irreversibility on the overall entropy generation. The transport equations are solved using two recent numerical methods, the overlapping grid spectral collocation method and the bivariate spectral quasilinearization method, first to determine which of these methods is the most accurate, and secondly to authenticate the numerical accuracy of the results. Further, we determine the skin friction coefficient and the changes in the heat and mass transfer coefficients with various system parameters. The results show, inter alia that reducing the heat transfer coefficient, the particle Brownian motion parameter, chemical reaction parameter, Brinkman number, thermophoresis parameter and the Hartman number all lead individually to a reduction in entropy generation. The overlapping grid spectral collocation method gives better computational accuracy and converge faster than the bivariate spectral quasilinearization method. The fluid flow problems have engineering and industrial applications, particularly in the design of cooling systems and in aerodynamics

Impact of thermal radiation on electrical MHD flow of nanofluid over nonlinear stretching sheet with variable thickness

The present paper addresses magnetohydrodynamics (MHD) flow of nanofluid towards nonlinear stretched surface with variable thickness in the presence of electric field. The analysis is presented with viscous dissipation, Joule heating, and chemical reaction. Characteristics of heat transfer are analyzed with the electric field and variable thickness phenomenon. The partial differential equations are converted into dimensionless ordinary differential equations by employing suitable transformations. Implicit finite difference scheme is implemented to solve the governing dimensionless problems. Behaviors of several sundry variables on the flow and heat transfer are scrutinized. Skin friction coefficient, the local Nusselt number local Sherwood number are presented and evaluated. It is observed that the skin friction, the rate of heat and mass transfer reduces with a rise in wall thickness. Electric field enhances the nanofluid velocity and temperature but reduced the concentration. Thermal radiation is sensitive to an increase in the nanofluid temperature and thicker thermal boundary layer thickness. Obtained results are also compared with the available data in the limiting case and good agreement is noted