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

Analysis of heat transfer for unsteady MHD free convection flow of rotating Jeffrey nanofluid saturated in a porous medium

In this article, the influence of thermal radiation on unsteady magnetohydrodynamics (MHD) free convection flow of rotating Jeffrey nanofluid passing through a porous medium is studied. The silver nanoparticles (AgNPs) are dispersed in the Kerosene Oil (KO) which is chosen as conventional base fluid. Appropriate dimensionless variables are used and the system of equations is transformed into dimensionless form. The resulting problem is solved using the Laplace transform technique. The impact of pertinent parameters including volume fraction φ, material parameters of Jeffrey fluid λ1, λ, rotation parameter r, Hartmann number Ha, permeability parameter K, Grashof number Gr, Prandtl number Pr, radiation parameter Rd and dimensionless time t on velocity and temperature profiles are presented graphically with comprehensive discussions. It is observed that, the rotation parameter, due to the Coriolis force, tends to decrease the primary velocity but reverse effect is observed in the secondary velocity. It is also observed that, the Lorentz force retards the fluid flow for both primary and secondary velocities. The expressions for skin friction and Nusselt number are also evaluated for different values of emerging parameters. A comparative study with the existing published work is provided in order to verify the present results. An excellent agreement is found

Upshot of heterogeneous catalysis in a nanofluid flow over a rotating disk with slip effects and Entropy optimization analysis

The present study examines homogeneous (HOM)–heterogeneous (HET) reaction in magnetohydrodynamic flow through a porous media on the surface of a rotating disk. Preceding investigations mainly concentrated on the catalysis for the rotating disk; we modeled the impact of HET catalysis in a permeable media over a rotating disk with slip condition at the boundary. The HOM reaction is followed by isothermal cubic autocatalysis, however, the HET reactions occur on the surface governed by first-order kinetics. Additionally, entropy minimization analysis is also conducted for the envisioned mathematical model. The similarity transformations are employed to convert the envisaged model into a non-dimensional form. The system of the modeled problem with ordinary differential equations is analyzed numerically by using MATLAB built-in bvp4c function. The behavior of the emerging parameters versus the thermal, concentration, and velocity distributions are depicted graphically with requisite discussion abiding the thumb rules. It is learned that the rate of the surface catalyzed reaction is strengthened if the interfacial area of the permeable media is enhanced. Thus, a spongy medium can significantly curtail the reaction time. It is also noticed that the amplitude of velocity and thermal profile is maximum for the smallest value of the velocity slip parameter. Heat transfer rate declines for thermophoresis and the Brownian motion parameter with respect to the thermal slip parameter. The cogency of the developed model is also validated by making a comparison of the existing results with a published article under some constraints. Excellent harmony between the two results is noted

On Combined Effects of Heat Transfer and Chemical Reaction for the Flow through an Asymmetric Channel with Orthogonally Deformable Porous Walls

The combined effects of heat transfer and chemical reaction are studied for the flow through a semi-infinite asymmetric channel with orthogonally deformable porous walls. The similarity transforms have been used to reduce the conservation laws to a corresponding system of nonlinear ordinary differential equations. The resulting equations are solved, both analytically and numerically, by using Homotopy Analysis Method (HAM) and the fourth-order Runge-Kutta (RK-4) method, respectively. The convergence of the analytical solution is assured through the so-called total squared residual error analysis. The optimal values of auxiliary parameters are obtained by minimizing the total squared residual error

Numerical Simulation of a Time-Dependent Electroviscous and Hybrid Nanofluid with Darcy-Forchheimer Effect between Squeezing Plates

In this article, the behavior of transient electroviscous fluid flow is investigated through squeezing plates containing hybrid nanoparticles. A hybrid nanofluid MoS2+Au/C2H6O2−H2O was formulated by dissolving the components of an inorganic substance such as molybdenum disulfide (MoS2) and gold (Au) in a base fluid of ethylene glycol/water. This hybrid non-liquid flow was modeled by various nonlinear mathematical fluid flow models and subsequently solved by numerical as well as analytical methods. For the numerical solution of nonlinear ODEs, a built-in function BVP4C was used in MATLAB, and the same problem was solved in MATHEMATICA by HAM. The result of the present problem related to the results obtained from the existing literature under certain conditions. The outcomes revealed that the concentration profiles were more sensitive to homogeneity diversity parameters. The simulation of the various physical parameters of the model indicated that the heat transfer through a mixture of hybrid nanofluids was greater than a simple nanofluid. In addition, the phenomenon of mixed convection was considered to improve the velocity of simple nanofluids and hybrid nanofluids, when both cases have low permeability. A rise in the volume fraction of the nanomaterials, Φ, was associated with an increase in the heat transfer rate. It was observed that the heat transfer rate of the hybrid nanofluids MoS2+Au/C2H6O2−H2O was higher than that of the single nanofluids MoS2/C2H6O2−H2O.We acknowledge the insightful comments of the editorial board to improve this work. We also acknowledge the financial support provided by the Postdoctoral research support fund of the School of Mathematical Sciences, Jiangsu University, Zhenjiang, China. The work of U.F.-G. was supported by the government of the Basque Country for the ELKARTEK21/10 KK-2021/00014 and ELKARTEK20/78 KK-2020/00114 research programs

Unsteady squeezing flow of a magnetized nano-lubricant between parallel disks with Robin boundary conditions

The aim of the present work is to examine the impact of magnetized nanoparticles (NPs) in enhancement of heat transport in a tribological system subjected to convective type heating (Robin) boundary conditions. The regime examined comprises the squeezing transition of a magnetic (smart) Newtonian nanolubricant between two analogous disks under an axial magnetism. The lower disk is permeable whereas the upper disk is solid. The mechanisms of haphazard motion of NPs and thermophoresis are simulated. The non-dimensional problem is solved numerically using a finite difference method in the MATLAB bvp4c solver based on Lobotto quadrature, to scrutinize the significance of thermophoresis parameter, squeezing number, Hartmann number, Prandtl number and Brownian motion parameter on velocity, temperature, nanoparticle concentration, Nusselt number, factor of friction and Sherwood number distributions. The obtained results for the friction factor are validated against previously published results. It is found that friction factor at the disk increases with intensity in applied magnetic field. The haphazard (Brownian) motion of nanoparticles causes an enhancement in thermal field. Suction and injection are found to induce different effects on transport characteristics depending on the specification of equal or unequal Biot numbers at the disks. The main quantitative outcome is that, unequal Biot numbers produce significant cooling of the regime for both cases of disk suction or injection, indicating that Robin boundary conditions yield substantial deviation from conventional thermal boundary conditions. Higher thermophoretic parameter also elevates temperatures in the regime. The nanoparticles concentration at the disk is boosted with higher values of Brownian motion parameter. The response of temperature is similar in both suction and injection cases; however, this tendency is quite opposite for nanoparticle concentrations. In the core zone, the resistive magnetic body force dominates and this manifests in a significant reduction in velocity i.e. damping. The heat buildup in squeeze films (which can lead to corrosion and degradation of surfaces) can be successfully removed with magnetic nanoparticles leading to prolonged serviceability of lubrication systems and the need for less maintenance

Prediction of thermal and energy transport of MHD Sutterby hybrid nanofluid flow with activation energy using Group Method of Data Handling (GMDH)

The present research work pursues GMDH for predicting thermal and energy transport of 2-D radiative magnetohydrodynamic (MHD) flow of hybrid Sutterby nanofluid across a moving wedge with activation energy. An exclusive class of nanoparticles SWCNT-Fe(3)O(4 )and MWCNT-Fe3O4 are dispersed into the ethylene glycol as regular fluid. The hybrid nanofluid mathematical model has been written as a system of partial differential equations (PDEs), which are then converted into ordinary differential equations (ODEs) through similarity replacements. Numerical solutions are attained Runge-Kutta-Fehlberg's fourth fifth-order (RKF-45) scheme by adopting the shooting technique. The ranges of diverse sundry parameters used in our study are Hartree parameter 0.1 <= m <= 0.5, magnetic parameter 0.3 <= M <= 1, Deborah number 0.1 <= De <= 1, moving wedge parameter 0.3 <= gamma <= 0.9, Reynolds number 0 <= Re <= 2.5, solid volume fraction of Fe3O4 and CNTs0.005 <= phi(1) <= 0.1,0.005 <= phi(2) <= 0.06, Browanian motion 0.1 <= Nb <= 0.4, thermophoresis parameter 0.1 <= Nt <= 0.25, Eckeret number 0.05 <= Ec <= 1, radiation parameter 1 <= R-d <= 2.5, Lewis number 0.5 <= Le <= 1.5, chemical reaction rate 0.1 <= sigma <= 0.7, heat source parameter, 0 <= delta <= 1.5 and activation energy 1 <= E <= 4 which shows up during the speed, thermal, and focus for Fe3O4/C2H6O2 nanofluid and CNTs-Fe3O4/C2H6O2 hybrid nanofluid. Additionally, the friction coefficient (C-fx), rate of heat transport (H-tx), and rate of nanoparticle transport (Nt(x) are calculated using GMDH. The numerical results for the current analysis are illustrated via tables, graphs, and contour plots. The efficiency of the proposed GMDH models is assessed using statistical measures such as MSE, MAE, RMSE, R, Error mean and Error StD. The predicted values are very close to the numerical results, and the coefficient of determination R-2 of C-fx,N-tx, and H-tx are 1, 0.97836 and 0.9960, respectively, which shows the best settlement

Numerical study of slip effects on unsteady aysmmetric bioconvective nanofluid flow in a porous microchannel with an expanding/ contracting upper wall using Buongiorno’s model

In this paper, the unsteady fully developed forced convective flow of viscous incompressible biofluid that contains both nanoparticles and gyrotactic microorganisms in a horizontal micro-channel is studied. Buongiorno’s model is employed. The upper channel wall is either expanding or contracting and permeable and the lower wall is static and impermeable. The plate separation is therefore a function of time. Velocity, temperature, nano-particle species (mass) and motile micro-organism slip effects are taken into account at the upper wall. By using the appropriate similarity transformation for the velocity, temperature, nanoparticle volume fraction and motile microorganism density, the governing partial differential conservation equations are reduced to a set of similarity ordinary differential equations. These equations under prescribed boundary conditions are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order numerical quadrature in the MAPLE symbolic software. Excellent agreement between the present computations and solutions available in the literature (for special cases) is achieved. The key thermofluid parameters emerging are identified as Reynolds number, wall expansion ratio, Prandtl number, Brownian motion parameter, thermophoresis parameter, Lewis number, bioconvection Lewis number and bioconvection Péclet number. The influence of all these parameters on flow velocity, temperature, nano-particle volume fraction (concentration) and motile micro-organism density function is elaborated. Furthermore graphical solutions are included for skin friction, wall heat transfer rate, nano-particle mass transfer rate and micro-organism transfer rate. Increasing expansion ratio is observed to enhance temperatures and motile micro-organism density. Both nanoparticle volume fraction and microorganism increases with an increase in momentum slip. The dimensionless temperature and microorganism increases as wall expansion increases. Applications of the study arise in advanced nanomechanical bioconvection energy conversion devices, bio-nano-coolant deployment systems etc

Effect of Variable Thermal Conductivity and Viscosity on MHD Casson Nanofluid Flow Vertical Plate through Thermal Radiation Convective Temperature along with Velocity Slip

This article presents the influences of connected variable thickness with created conductivity, nanofluid flow over a vertical level plate through convective smooth, with velocity slip boundary surroundings. The controlling vehicle nonlinear divided differential stipulations with the interrupt surroundings are non- dimensionalized. The reachable path of motion of certain existing differential conditions is then diminished to a set of joined nonlinear quintessential differential conditions utilizing convenience modify. Numerical outcomes are getting for dimensionless velocity, temperature, and nanoparticle quantity. It is discovered that the velocity increments, while each temperature and nanoparticle extent partrot with improved estimations of variable maximum conductivity and consistency. At the same time as the Dufour range and Soret, comprehensive range augmentation with working up the relative and the thing subject decompose as the Schmidt range tendencies while the temperature area decreases with extending Prandtl number and Dufour number correlations are executed with scattered facts virtually taking parent proper now the numerical outcomes. Surprising consideration is seen. Taking the entirety into account, the effects of essential parameters on fluid velocity, temperature, and focus on dispersion moreover as on the partition total mass, heat, and mass exchange figures are audited in detail. Also, this existing consideration can determine purposes in the method, which include nanofluid works out