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The current study focuses on utilizing an advanced statistical concept for optimizing rate of heat transfer in a micropolar nanofluid flow within a squeezing channel. The study employs RSM to plan experiments and analyze the role of distinct constraints on HT performance. Moreover, the inclusion of dissipative heat due to the interaction of applied magnetic field along with thermal radiation enriches the study. The proposed designed model is transformed to its non-dimensional form using appropriate similarity rules and then numerical simulation is presented to solve the set of formulated problem. However, the irreversibility process of the system is assessing by incorporating the entropy analysis. The validation along with the characteristic of the contributing factor is presented via the solution of the present design. The outcomes reveals that enhanced volume fraction generally increases viscosity of the fluid which resulted in a strong retardation in the fluid velocity. However, the entropy rate augments with an increasing Br. The results provide the optimal conditions for HTR for both of the nanofluids, which is relevant for applications in drug delivery systems. The advancement in optimizing HTR using RSM and the regression analysis using ANOVA (analysis of variance) may have potential implications for biomedical engineering.

The role of natural convection NC in nanofluids is vital to the heat transfer efficiency of various thermal systems, including solar energy devices, HVAC systems, and heat exchangers. This research examines the NC of TiO2-water nanofluid in a porous wavy circular area with a ┴shaped heater under a constant magnetic field. The governed equations may well be solved utilizing the finite element technique, and the impact of various variables, such as the volume fraction of nanofluid (φ), radiation parameter (Rd), Rayleigh number (Ra), aspect ratio (AR), and Hartmann number (Ha), on the heat transfer of the ferrofluid is analyzed. The findings show that amplifying the aspect ratio from 0.3 to 0.5 reduces the local Nusselt number by up to 35%. Additionally, increasing the Ha from 0 to 40 results in a decrease in the maximum streamline by 85%.

In industry, double-diffusive convection has various and important technical applications. These applications include electronic apparatus cooling, drying processes, fuel cells, geothermal engineering, and thermal storage. We provide an entropy-thermal based analysis of magnetized Boussinesq-free double-diffusive convection engendered by internal heat and concentration source block in a nanofluid-filled C-shaped inclined confined space. Findings may be interpreted and assessed in terms of the leading variables such as Lewis number (Le = 2 to 8), Hartmann number (Ha= 0 to 20), buoyancy ratio (N = 1 to 3), and Rayleigh number (Ra = 105 and 106). Besides, to determine the effective geometry and good control of the phenomenon, the investigation also covered the system geometry parameters including the position of the concentration and heat source block (h/L = 0.2 to 0.8) and the inclination angle of the enclosure (δ = 0°–90°). We state that the mass and heat transfer rates increase with Ra, N, and δ while decreasing with Ha, Le, and h/L parameters. Furthermore, when Le, Ha, N, and δ increase, overall entropy increases, whereas it decreases as the h/L parameter increases.

The emphasis of this study is the numerical analysis via finite volume method of magneto-natural convection induced by double-diffusion of a nanofluid within an enclosure equipped with a wavy porous cylinder. The porous cylinder which is under the local thermal non-equilibrium (LTNE) situation is modeled using Darcy-Brinkman-Forchheimer design as momentum equation. Results are interpreted and evaluated in terms of the dimensionless controlling variables such as Rayleigh number (Ra), Lewis number (Le), Hartman number (Ha), buoyancy ratio parameter (N), Darcy number, (Da), and medium's porosity (ε) at a given heat transfer coefficient for the solid/fluid inter-phase (H) and modified conductivity ratio (γ) of the porous wavy cylinder region. Corcione's correlations with 4% of Al2O3 nanoparticles is used to estimate nanofluid's thermal conductivity and viscosity. Findings show that the heat and mass transfers are improved by Ra, Da, and ε augmentation and Ha and Le diminution. In general, as Le increases, the mass transfer rate rises while the corresponding heat transfer rate drops. Also, we identified a value of N where Le-dependent heat and mass transfer rates are minimal. Moreover, the heat transfer rate is found to be more sensitive to the changes in the porous medium's properties of the wavy porous cylinder than the mass transfer rate. Furthermore, the LTNE situation everywhere exists in the porous wavy cylinder except for the center where the LTE is realized.

This investigation deals with the flow of Al2O3–water nanofluid in a wavy porous channel embedded in porous rocks. Fluid exchange takes place uniformly between porous rocks and the wavy channel. In this analysis, cylindrical and parallel plate wavy porous channels are considered. Consequences of Brownian motion and thermophoresis on the flow inside a wavy porous channel are elucidated. The modeled equations are made dimensionless by using dimensionless quantities. Impacts of flow parameters on the velocity, temperature, Nusselt number and friction factor are depicted through graphs. The numerical results with respect to parallel plate wavy porous channel are validated by comparing with the published results. The effectiveness of the cylindrical wavy porous channel as a heat transfer enhancement device in comparison to the parallel plate wavy porous channel is confirmed in this study. Designing devices at microlevels and understanding the heat transfer enhancement mechanism in wavy channels using the nanoparticle addition are the major outcomes from the results of this numerical investigation. The heat and mass transfer rate enhancements in the wavy porous channels are due to the higher Brownian motion in the boundary layer region and accelerated thermophoresis through thermal and concentration boundary layer thicknesses. [ABSTRACT FROM AUTHOR]

To achieve ultra-high cooling rate requirement of modern-day industries the combined use of nanofluid and porous medium in several engineering and industrial processes provides excellent outcomes. In present analysis, the comparison between the flows of Gr-w and GO-w nanofluids over exponential shrinking sheet inside porous medium is investigated. Governing coupled PDEs are changed into ODEs by appropriate transformations which are solved numerically with the help of shooting method with RK4; and obtained dual solutions of Darcy flow for certain enforced mass suction exist and consequently, a stability analysis is performed to test physical stability of both solutions which proves physical stability of upper solution branch and instability of lower solution branch. The impacts of several physical parameters are presented in graphical modes along with a tabular comparison. The study reveals that Gr-w nanofluid delays the boundary layer flow separation more in comparison with GO-w nanofluid and hence, the requirement of mass suction for existence of Gr-w nanofluid flow is of lower amount. Also, consideration of porous material as flow medium defers the separation phenomenon. The rise of surface-drag force is witnessed for porous medium and mass suction and it is relatively larger for Gr-w nanofluid than GO-w nanofluid in case of upper branch solution and the surface cooling rate is larger for Gr-w nanofluid in comparison with GO-w nanofluid.

An exploration of the unsteady MHD boundary layer flow over a moving vertical porous surface with nanofluids under the influence of a uniform transverse magnetic field and heat radiation absorption effects has been brought out. Two different kinds of water-based nanofluids comprising of Al2O3 and TiO2 are adopted into deliberation. The governing equations for the flow are solved by making use of the Laplace transform method, and the solutions are displayed in closed form. The velocity, temperature, concentration, the shear stress, the rate of heat and mass transportations near the surface has been described graphically for numerous values of the relevant parameters. The velocity and temperature enhances with increasing radiation absorption parameter. It is also observed that an increase of volume fraction of nanoparticles leads to the enhancement of the temperature on central line of the flow. Nusselt number might be tracked down to be elevated for alumina than titanium dioxide nanofluid. The present investigation originated applications in aerospace engineering as well as industrial many mechanisms.

An analysis into the transient natural convective flow of a nanofluid in a vertical tube is made. The governing equations of momentum, heat transfer and nanoparticle volume fraction are deduced, and the influence of the thermophoresis parameter and Brownian motion is incorporated. By direct integration and variation of the parameter, analytical solutions are obtained for flow formation and heat/mass transfer at steady-state. On the other hand, due to the complexity of same problem at transient state, a numerical solution is used to solve the discretized equations of motion using the implicit finite difference technique. The influence of the thermophoresis parameter and Brownian motion is noted and well discussed. For accuracy check, a numerical comparison is made between the steady state and transient state solution at large time; this comparison gives an excellent agreement. The role of various principal parameters on velocity profile, temperature, concentration of nanoparticles, Sherwood and Nusselt numbers are presented graphically and well discussed. It is noted that the buoyancy ratio decreases the fluid velocity significantly.

The combined effects of diffusion-thermo and radiative absorption on free convective hydromagnetic heat-generating chemically reactive flow of Cu-water nanofluid past an instantaneously accelerated unlimited vertical plate nested in a porous medium are investigated. A comparative analysis is executed for both isothermal and ramped conditions. The set of transformed domain equations has been obtained using a closed form of the Laplace transform method with the help of the Heaviside step function. Graphical and tabular explanations are provided for the physical characteristics of several flow parameters affecting the problem. Graphs are generated using MATLAB computing software. Findings of the problem manifest that the diffusion-thermo parameter and the radiation absorption parameter intensify the velocity and fluid temperature in the entire fluid area. This augmentation is most prominent for copper nanoparticles. Concentration, temperature, and velocity profiles in the case of ramped conditions are less than in isothermal conditions. Furthermore, the ramped parameter amplifies the heat transfer rate while reversing the mass transfer rate. It is also established that the volume concentration of nanoparticles enhances the heat transfer rate. The present study is of great interest in numerous fields of industry and machine-building applications. [ABSTRACT FROM AUTHOR]

In this study, mixed convection regarding nanofluid within the wavy lid-driven enclosure and a prominent heat source is investigated. A two-phase method is applied to the employed nanoliquid which leads to a non-homogeneous concentration field. The obtained governing equations are solved by the finite element technique. The effects of adding nanoparticles in base flow on velocity, temperature, and concentration field are investigated. Also, the effects of different geometric dimensions on heat transfer, such as heat source aspect ratio, wave number, and amplitude of wavy walls are investigated. The outcomes reveal that increasing the application of nanoparticles, wave number and amplitude of the wavy wall, and aspect ratio of heat source yields an improvement within the rate of heat transfer.

Heat and flow pattern of a vertical free jet impinging on a hot disk were numerically investigated. A cylinder with various thicknesses and materials exposed simultaneously to uniform heat flux on one side and a free impinging jet on the other side is simulated by ANSYS Fluent 19.3. For simulations, the thermal boundary condition on the hot surface might differ due to the nature of the heat flow. The Volume of Fluid (VOF) approach is used to model the free jet heat transfer and fluid dynamics with the presence of air, while only the energy equation is solved in the cylinder. Heatline equation is solved to reveal the heat flow direction and effects of different geometry conditions. The maximum heat flux of 2.5 MW/m2 was obtained at the edge of stagnation region for hot target made of copper, while the value was 1.5 MW/m2 when the material was combined with stainless steel. However, the general thermal and hydrodynamic features of the jet flow were not influenced. It means that hot object condition may only affect the balance between heat flux and temperature, and the ideal uniform heat flux on the impinging wall may not be achieved in any experimental conditions.

Nanofluids behave like non-Newtonian fluids in many cases and, therefore, studying their symmetrical behavior is of paramount importance in nanofluid heat transfer modeling. This article attempts to provide are flection on symmetry via thorough description of a variety of non-Newtonian models and further provides a comprehensive review of articles on non-Newtonian models that have applied symmetrical flow modeling and nanofluid heat transfer. This study reviews articles from recent years and provides a comprehensive analysis of them. Furthermore, a thorough statistical symmetrical analysis regarding the commonality of nanoparticles, base fluids and numerical solutions to equations is provided. This article also investigates the history of nanofluid use as a non-Newtonian fluid; that is, the base fluid is considered to be non-Newtonian fluid or the base fluid is Newtonian, such as water. However, the nanofluid in question is regarded as non-Newtonian in modeling. Results show that 25% of articles considered nanofluids with Newtonian base fluid as a non-Newtonian model. In this article, the following questions are answered for the first time: Which non-Newtonian model has been used to model nanofluids? What are the most common non-Newtonian base fluids? Which numerical method is most used to solve non-Newtonian equations?

This paper was written to demonstrate the value of using nanofluids for cooling high power transformers while also providing current techniques for business and academia. A numerical analysis of the improvement caused by the cooling of a high voltage transformer using nanofluids has been done. A tank with a temperature source inside and a charge of mineral oil-barium titanate nanoparticles is used to study natural-convection. This study investigates the effects of variables on the thermal efficiency of the tank, including the thermal Rayleigh number and volume fraction. The results show that quenching varies with low and high Rayleigh thermal numbers and depends on the volume percentage of used nanoparticles. The effects were illustrated in thermal transfer rate representations as functions of the thermal Rayleigh number (Rat = 103 and 106) and the solid volume particle from the nanoparticles (0% = f < 10%). The findings showed that improving the solid volume particle of the nanoparticles by 10% causes the fluid being utilized to become more effectively conductive, which improves the rate of heat transfer by roughly 10% when compared to the case of the base fluid. [ABSTRACT FROM AUTHOR]

Abstract This article unveils the combined impact of heat generation/absorption and Joule heating on MHD flow of Ag-H2O nanofluid into a porous stretching/shrinking divergent/convergent channel with viscous dissipation and solid volume fraction. The mathematical modeling is presented for the existing equations of continuity, momentum, and energy fraction. The reduced boundary value problem is solved numerically employing Runge-Kutta-Fehlberg (RKF) method via shooting scheme and then the outcomes are sketched and interpreted. The results explore that the thermal boundary layer thickness of the stretching divergent and the shrinking divergent channels enhance by increasing the value of the Eckert number, while the opposite tendency is scrutinized on the momentum boundary layer thickness by increasing the value of the porosity parameter for the stretching divergent and the shrinking convergent channels.

The present article reveals the study of heat transfer via buoyancy-driven flow and entropy generation of magnetic Fe3O4–H2O nanoliquid inside a porous enclosure using two square cylinders. The shape factor of diverse particle shapes may well be also considered. Numerical technique called FEM is implemented for the transformed governing equations. Results of Nusselt number, entropy generation, Bejan number along with the streamlines and the isotherms are obtained for disparate contributing parameters. Validation with earlier studies exhibits an excellent agreement in particular case and findings portray that entropy generation rises with growing Hartmann number and mounting Rayleigh number could overshoot the velocity gradient within the enclosure.

Nanofluids have found extended applications in different industrial and engineering systems nowadays. This study aims to investigate the accurate prediction of SiO2 nanofluid effect on the heat transfer performance, specifically convective heat transfer coefficient (H), of a quadrangular cross-section channel by considering affecting fluid flow specifications factors of Re, Pr, and concentration of nanoparticles (x) in the employing working fluid. An experimental setup is used to prepare a database consisting of 270 data points on the H, of SiO2 nanofluids. These data are then applied to develop predictive models based on three intelligent algorithms, namely multi-layer perceptron (MLP), adaptive neuro-fuzzy inference system (ANFIS), and least squares support vector machine (LSSVM), respectively. Graphical and statistical error criterions are carried out to evaluate the credibility of the proposed approaches. The LSSVM method had the precise performance regarding the mean squared error (MSE) and the coefficient of determination (R2) of 59.7 and 0.9992, respectively. A sensitivity analysis is also carried out to assess the impact of different parameters on the H demonstrating that the Prandtl number has the highest impact with a relevancy factor (r) of 0.524.

A numerical investigation on the impacts of heater length increased from left corner along with the bottom wall in a Cu-water nanofluid-filled porous cavity in the existence of MHD and thermal radiation is performed out. The bottom wall is heated with two different types of heater (both uniform and nonuniform) separately. Three various lengths of heater are considered. Constant cold upper horizontal wall moves in the positive direction. The other sidewalls and excluding the heating portion of the bottom wall are considered to be adiabatic. The system of dimensionless form of governing equations is solved by finite volume method (FVM) with appropriate boundary and initial conditions and SIMPLE algorithm has been employed for the pressure term. For both types of heating, the highest heat transfer is attained with the length of heater L H = 1 / 4 for all taken Richardson number. The effect of magnetic field is very low on heat transfer with the thermal source length L H = 1 / 2 and nonuniform heating in free convection regime. On increasing the heater length in nonuniform heating, overall heat transfer rate is decreased first and then raised. The percentage of increasing of average Nusselt number with an increase of thermal radiation parameter in nonuniform heating is higher than uniform heating. The effect of magnetic field is significant for all taken solid volume fraction in uniform heating than the nonuniform heating with heater length L H = 1 / 2. [ABSTRACT FROM AUTHOR]