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The present paper aims to conduct a numerical investigation of the natural convective flow of Cu-water nanofluid in an isosceles triangular-shaped cavity, where an air stream cools the lateral walls while its base is subjected to discrete heating. The governing equations are numerically solved using the finite volume method (FVM) employing ANSYS FLUENT. The results are presented with diverse scopes of pertinent parameters, including non-dimensional heater length (L/H = 0.25, 0.5, and 1), Rayleigh Number (Ra = 104, 105, and 106), nanoparticles volume fraction (φ = 0, 0.03, 0.06 and 0.09), and free stream Reynolds number (Re∞ = 102, 103, 104 and 105). The impact of each of these parameters is depicted on the isotherms (θ) lines, stream function (ψ) contours, and the average Nusselt number (Nuavg) plots on the heated lower wall. The findings showed the subsequent enlargements in Nuavg with an increase in Ra by 515 %, L/H by 130 %, Re∞ by 43 %, and φ by 137 %, indicating an enhancement in the heat transfer rate with these parameters. Besides, extra secondary eddies will be generated inside the cavity when Ra becomes more extensive, while the flow configuration is not influenced by the enlargement of φ, Re∞, and L/H. The present model findings have been compared with other work from the literature and showed an acceptable agreement with a maximum error of less than 1 %.

This study explores forced convection in a viscous, electrically conducting fluid over a stretching sheet with variable thickness. It examines the effects of a varying free stream, magnetic field, and viscous dissipation on flow and heat transfer. The governing equations for mass, momentum, and energy are converted into ordinary differential equations using similarity transformations and solved numerically with the finite difference method. The results reveal dual solutions within specific parameter ranges: one stable and aligned with natural phenomena, the other unstable with higher skin friction and velocity. Viscous dissipation significantly alters velocity and temperature profiles. These insights are valuable for optimizing flow conditions in applications such as metal sheet cooling and polymer processing. [ABSTRACT FROM AUTHOR]

Variable fluid properties with thermal radiation in an unsteady magnetohydrodynamics free stream incompressible flow over a stretching sheet has been considered. The thermal diffusivity and viscosity of the fluid varies linearly with temperature. The governing partial differential equations are moulded to ordinary differential equations using time‐dependent similarity variables and the stream function. RKF technique with shooting method has been implement to find the solution numerically. In the current analysis the impact of unsteadiness, magnetic field, radiative parameter, variable fluid viscosity and thermal diffusivity parameter on heat and flow behavior with the free stream parameter have been studied. Transition point observed in the velocity profiles with an change in unsteadiness parameter and the effect of magnetic field is reduced in the presence of free stram velocity. The velocity and the temperature gradient are computed on the surface and their outcomes with different parameters have been analyzed in the results shown graphically and in tabular form. [ABSTRACT FROM AUTHOR]

The current study deals with the boundary layer flow of a magnetohydrodynamically conducting fluid through a porous material together with the effect of heat generation and velocity characteristics. The process of heat transfer, the effects of velocity slip and thermal slip on velocity and temperature profiles are also discussed. Using suitable simulation, the model governing system of partial differential equations are converted into nonlinear ordinary differential equations with required boundary conditions. The Modified Homotopy analysis method is used to solve the reduced ordinary differential equations analytically. The dimensionless characteristics such as magnetic parameter. grashof number, Heat production parameter, Prandtl number, and velocity slip parameter, are found to have a substantial impact on the outcomes. Graphs and tables depict the impact of relevant physical quantities on the velocity and temperature profile. [ABSTRACT FROM AUTHOR]

A large-scale two-dimensional computational fluid dynamics study is conducted in order to maximise the power output and smoothness of power delivery of a free-stream water wheel, a low-impact hydropower device. Based on models and methods developed in previous research, the study uses a genetic algorithm to optimise the geometry of a wheel with a given radius and depth, maximising two objective functions simultaneously. After convergence and suitable post-processing, a single optimal design is identified, featuring eight shortened blades that become fully immersed at the nadir point. The design results in a 71% reduction in blade material and a 113% increase in the work ratio while improving the hydraulic power by 8% compared to the previous best design. These characteristics are applied retroactively to a broad family of designs, resulting in significant improvements in performance. Analysis of the resulting designs indicates that when either the hydraulic power coefficient, rotor power coefficient, or work ratio is considered, free-stream water wheels with fully immersed blades, whose power mechanisms are shown to rely on lift, as well as drag, outperform all other designs studied so far. [ABSTRACT FROM AUTHOR]

The nanofluids are a recent challenging task in a nanotechnology field used in heat transfer enhancement for base fluids. The major purpose of this research is to examine the influences of Hall current on the non-Newtonian power-law nanofluid on an exponentially extending surface. Implementation in the Cattaneo–Christov heat flux and the free stream is performed to analyze the thermal relaxation features. Entropy generation evaluation and Bejan number during the convection flow are investigated. The Runge–Kutta–Fehlberg method is employed to resolve the transformed governing nonlinear equations. The impacts of the key physical factors on the profiles of primary and secondary velocities, temperature and entropy generation are discussed across the graphs. The local skin-friction coefficients, Nusselt and Sherwood numbers are demonstrated in a tabular form under the impacts of key physical parameters. Two different types of power-law indicators including pseudoplastic fluid (n = 0. 7) and dilatant fluid (n = 1. 2) are conducted. The results indicated that the flow speed decreases at dilatant fluid compared to pseudoplastic fluid due to higher viscosity. Increasing Hall current parameter powers the axial and secondary velocity profiles. Thermophoresis parameter powers the profiles of the temperature, nanoparticle volume fraction and local entropy generation. The dilatant fluid (n = 1. 2) gives higher values of C f x , C f z , Nu x and Sh x compared to the pseudoplastic fluid (n = 0. 7). [ABSTRACT FROM AUTHOR]

Steady, transverse boundary layer flow and heat transfer caused by an exponentially stretching cylinder of constant radius immersed in an uniform flow of an incompressible, viscous nanoliquid are considered in the present study. The paper discusses a systematic procedure of obtaining a local similarity transformation that reduces the governing partial differential equations into ordinary differential equations. Power series solution is then obtained for velocity, temperature and nanoparticle concentration distributions using the uni-variate differential transform method. Help is sought from Domb-Sykes plots in making a decision on the minimum number of terms required in the power series expansion to ensure convergence. Radius of convergence is quite naturally suggested by these plots. Pad ´ e approximants are then appropriately decided upon to increase the radius of convergence. The algorithm used succeeds in capturing boundary effects, free stream flow effects and nanoparticle effects on flow and heat transfer. An important finding of the paper is the prediction of accelerated cooling of the stretching cylinder due to the nanoparticles in the cooling liquid. In having a desirable property for the extruding cylinder nanoliquid coolant seems an attractive proposition.

The electrostatic fluid accelerator (EFA) generates ionic wind with a simple structure that barely obstructs the free air stream or produce excessive noise. This paper presents the velocity characteristics of an EFA under a high speed free air stream to simulate an EFA-powered propulsor. The results show that when the EFA generates identical velocity to the free air stream, the EFA contributes 25% of the resultant velocity. When the EFA is replaced by a rotary fan that generates identical velocity to the free air stream, the fan contributes only 13.4% of the resultant velocity. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Steady, transverse boundary layer flow and heat transfer caused by an exponentially stretching cylinder of constant radius immersed in an uniform flow of an incompressible, viscous nanoliquid are considered in the present study. The paper discusses a systematic procedure of obtaining a local similarity transformation that reduces the governing partial differential equations into ordinary differential equations. Power series solution is then obtained for velocity, temperature and nanoparticle concentration distributions using the uni-variate differential transform method. Help is sought from Domb-Sykes plots in making a decision on the minimum number of terms required in the power series expansion to ensure convergence. Radius of convergence is quite naturally suggested by these plots. Pad ´ e approximants are then appropriately decided upon to increase the radius of convergence. The algorithm used succeeds in capturing boundary effects, free stream flow effects and nanoparticle effects on flow and heat transfer. An important finding of the paper is the prediction of accelerated cooling of the stretching cylinder due to the nanoparticles in the cooling liquid. In having a desirable property for the extruding cylinder nanoliquid coolant seems an attractive proposition. [ABSTRACT FROM AUTHOR]