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The developing interest in thermal engineering and nano-technology presented the idea of nanoparticles with enhanced thermal mechanisms and attained convinced novel applications in heat transportation systems, solar energy, micromechanics, air conditioning systems, cooling and heating facilities, bio-medical applications like cancer treatment, artificial heart surgery etc. Beside this, the phenomenon of entropy generation is another fascinating research area which used to improve the assessment of heat transportation with optimized procedure. The entropy generation in bio-convective flow of Eyring-Powell nanofluid over permeable stretched surface of cylinder is scrutinized in this research. The effects of magnetic field, thermal radiation and viscous dissipation are considered. Concentration communication is obtained in view of activation energy associated with binary chemical reaction. Furthermore, properties of Brownian diffusion and thermophoresis of nanoparticles are accounted. Suspended nanoparticles are made stable through mutual effects of bioconvection and buoyancy forces. Total entropy generation rate is modeled through second thermodynamics law. The governing flow model is obtained with the help of boundary layer approximations. Dimensional model is transformed into non-dimensional one by transformations and then tackled by Newton built-in shooting procedure. Impact of different influential variables on entropy generation, velocity, temperature, concentration, Bejan number and motile density of microorganisms are analyzed via graphs. Numerical values of skin friction coefficient, density, Sherwood and Nusselt numbers are tabulated and examined. Major findings are listed at the end. Since this analysis is based on theoretical flow assumptions, therefore the flow parameters specify the constant range like 0.0 ⩽ Γ ⩽ 6.0 , 1.0 ⩽ γ ⩽ 4.0 , 0.1 ⩽ H a ⩽ 1.2 , 0.2 ⩽ λ ⩽ 0.6 , 0.2 ⩽ R d ⩽ 1.7 , 0.1 ⩽ K ⩽ 3.0 , 0.1 ⩽ Pr ⩽ 4.5 , 0.3 ⩽ N b ⩽ 1.8 , 0.2 ⩽ N t ⩽ 1.7 , 0.0 ⩽ E 1 ⩽ 1.0 , 1.0 ⩽ E c ⩽ 4.0 , 0.2 ⩽ σ ⩽ 1.4 , 0.4 ⩽ S c ⩽ 1.7 , 1.0 ⩽ δ ⩽ 2.5 , 0.5 ⩽ P e ⩽ 2.0 , 0.5 ⩽ Ω ° ⩽ 2.0 , 0.1 ⩽ B r ⩽ 1.0 , 0.1 ⩽ L b ⩽ 1.5. The results show that fluid velocity decreases with curvature parameter and porosity constant. A decreasing variation in nanofluid temperature due to curvature parameter is examined. The entropy generation and Bejan number decline Brinkman number, motile density diffusion parameter and mass concentration diffusion variable. Furthermore, it is observed that skin friction coefficient increases with curvature parameter and porosity constant. [ABSTRACT FROM AUTHOR]

Owing to the improved thermophysical properties of nano-materials, the nanofluid convey novel applications in industries, engineering as well as bio-medicals. With high efficiency performances, the nanoparticles include applications in various cooling and heating systems, energy production, aerospace engineering, thermal extrusion, bio-medical applications like treatment of diseases, brain tumour, surgical applications and many more. Moreover, the magneto-nanofluids have the characteristics in the flow of blood in the human artery. The current analysis deals with the free convective unsteady flow of viscous nanofluid subject to the magnetic force over a vertical plate in presence of porous space. The heat transfer phenomenon is accessed by utilizing the additional features like Joule heating, viscous dissipation and absorption coefficients. In addition to the volume fraction of the nanofluid, the effect of the chemical reaction is also introduced. The solution procedure for the modified time-dependent boundary value problem is performed by using the code in-build MATLAB namely Built-in-Shooting method. The change in velocity, temperature and concentration of nano-materials is examined through various graphs. The physical consequences of flow parameters like porosity parameter K p 1 ⩽ K p ⩽ 3 , thermal Grashoff number Gr 1 ⩽ G r ⩽ 3 , solutal Grashoff number Gc 1 ⩽ G c ⩽ 3 , magnetic field parameter M 1 ⩽ M ⩽ 3 , thermal radiation parameter Nr 0.1 ⩽ N r ⩽ 1 , radiation absorption parameter Q 0 ⩽ Q ⩽ 0.5 , Prandtl number Pr 2 ⩽ Pr ⩽ 21 , Eckert number Ec 0 ⩽ E c ⩽ 0.4 , heat source S - 0.2 ⩽ S ⩽ 0.2 , chemical reaction parameter Kc 1 ⩽ K c ⩽ 4 , nanoparticles volume fraction ϕ 0.0 ⩽ ϕ ⩽ 0.1 , Lewis number Le 1 ⩽ L e ⩽ 10 on velocity, temperature and concentration distributions is graphically analyzed. The results show that skin friction coefficients decline with buoyant forces. A lower numerical variation in Nusselt number is resulted with heat source parameter. Moreover, a sharp fall in nanofluid concentration is noticed with increment of chemical reactants and Lewis number. [ABSTRACT FROM AUTHOR]

This contemporary study is done to analyze the comparative study of hybrid nanofluids motion due to semi-infinite asymmetric channel with contracting and expanding porous walls orthogonally. Boundary conditions considered are convective conditions. Hybrid nanofluids consist of more than two nanoparticles. Purpose of nanofluid is to enhance the heat transfer characteristics by adding nanoparticles into base fluid. When we add two nanoparticles collectively to form nanofluid than it is more useful. Maganese Zinc ferrite and Nickle Zinc ferrite are used as nanoparticles and engine oil and Kerosene oil are considered in place of base fluid. Nonlinear heat source sink effect is considered along with activation energy. Darcy Forchheimer porous medium is considered in momentum equation. We have introduces suitable transformations to get ODE's from PDE's. Homotopy analysis method is used to find the convergent solution. For more accuracy tables are also drawn for convergent solution. Velocity for M n Z n F e 2 O 4 - N i Z n F e 2 O 4 - C 10 H 22 - C 8 H 18 is lowest among all. Impact of important parameters along velocity, temperature, concentration, skin friction and Nusselt number is seen through graphs. For positive values of wall contraction (or expansion) rate parameter velocity of the fluid enhances. Motion slows down for greater Forchheimer number. Temperature rises via thermal Biot number. Concentration profile is increasing with larger estimation of activation energy. [ABSTRACT FROM AUTHOR]

Present article reads three dimensional flow analysis of incompressible viscous hybrid nanofluid in a rotating frame. Ethylene glycol is used as a base liquid while nanoparticles are of copper and silver. Fluid is bounded between two parallel surfaces in which the lower surface stretches linearly. Fluid is conducting hence uniform magnetic field is applied. Effects of non-linear thermal radiation, Joule heating and viscous dissipation are entertained. Interesting quantities namely surface drag force and Nusselt number are discussed. Rate of entropy generation is examined. Bvp4c numerical scheme is used for the solution of transformed O.D.Es. Results regarding various flow parameters are obtained via bvp4c technique in MATLAB Software version 2019, and displayed through different plots. Our obtained results presents that velocity field decreases with respect to higher values of magnetic parameter, Reynolds number and rotation parameter. It is also observed that the temperature field boots subject to radiation parameter. Results are compared with Ishak et al. (Nonlinear Anal R World Appl 10:2909–2913, 2009) and found very good agreement with them. This agreement shows that the results are 99.99% match with each other. [ABSTRACT FROM AUTHOR]

• Evaluating the effects of nano-materials and corrugated tube on energy efficiency of a PTSC. • Usage of corrugated absorber tube has a significant effect on energy efficiency. • Usage of double fluid system at higher re is efficient. • Efficiency of the PTSC enhances with increasing the nanoparticles concentration. • Presenting optimum model of corrugated absorber tube. Parabolic trough solar collectors (PTSCs) are used to focus the solar rays on absorber tube. The main aim of this paper is to investigate the effects of applying novel corrugated absorber tube filled with hybrid nanofluid on energy efficiency of a novel double fluid PTSC to achieve the maximum energy efficiency value. The Eulerian-Eulerian two-phase model is employed for modelling the PTSC and evaluating its energy efficiency. Numerical study is carried out for different values of Reynolds number (Re), nanoparticles volume fraction (ϕ) and geometrical parameters of novel corrugated absorber tube. It is found that usage of corrugated absorber tube has a significant effect on energy efficiency of single- or double fluid parabolic trough solar collectors. Besides it is understood that usage of double fluid system for collector with smooth channel can also increase the energy efficiency, but not more than using corrugated channel for single fluid collector. Moreover, usage of double fluid system at higher Re is also efficient. The results also show that the efficiency of the PTSC enhances with increasing the nanoparticles concentration. Finally, the optimum model of corrugated absorber tube is presented. [Display omitted] [ABSTRACT FROM AUTHOR]

Colloidal suspensions of regular fluids and nanoparticles are known as nanofluids. They have a variety of applications in the medical field, including cell separation, drug targeting, destruction of tumor tissue, and so on. On the other hand, the dispersion of multiple nanoparticles into a regular fluid is referred to as a hybrid nanofluid. It has a variety of innovative applications such as microfluidics, heat dissipation, dynamic sealing, damping, and so on. Because of these numerous applications of nanofluids in minds, therefore, the objective of the current exploration divulged the axisymmetric radiative flow and heat transfer induced by hybrid nanofluid impinging on a porous stretchable/shrinkable rotating disc. In addition, the impact of Smoluchowski temperature and Maxwell velocity slip boundary conditions are also invoked. The hybrid nanofluid was formed by mixing the copper (Cu) and alumina (Al2O3) nanoparticles scattered in the regular (viscous) base fluid (H2O). Similarity variables are used to procure the similarity equations, and the numerical outcomes are achieved using bvp4c in MATLAB software. According to the findings, double solutions are feasible for stretching (λ > 0) and shrinking cases (λ < 0) . The heat transfer rate is accelerated as the hybrid nanoparticles increases. The suction parameter enhances the friction factors as well as heat transfer rate. Moreover, the friction factor in the radial direction and heat transfer enrich for the first solution and moderate for the second outcome due to the augmentation δ 1 , while the trend of the friction factor in the radial direction is changed only in the case of stretching for both branches. [ABSTRACT FROM AUTHOR]

The nanomaterials are more efficient in different areas like in pharmacy industry, cooling of compressors, engines, heating materials, damage cells destruction and brain tumors etc. The foremost aim of the this communication is to scrutinize the effects of activation energy on the nanofluid flow of an infinite, rotating and stretchable disk in radial direction with thermal heat source (THS) and the exponential space heart source (ESHS). Brownian and thermophoresis diffusions are countered to study the nanofluid. The Coriolis force and effects of radial magnetism are deployed. Nonlinear Boungiorno model is utilized. The modeled PDEs are converted to system of ODEs via proper variables. The obtained system is approximated through NDSolve technique. Features of various variables on flow profiles are examined and outcomes are declared via curves and tables. It is investigated that ESHS is highly influential than THS on fluid temperature. Furthermore it is found that activation energy enhances the concentration. [ABSTRACT FROM AUTHOR]