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Abstract The interfacial nanolayer is a tinny coating of liquid molecules convened around the immersed solid nanoparticles in the base liquid which plays a vital role to control the flow and improve the thermophysical properties of the fluid. Features are more prominent for hybrid nanomaterials. Hence, the present analysis deals with the concomitant effects of an interfacial nanolayer of nanomaterials MWCNT and Ag during a viscous Darcy Forchheimer flow over a moving needle. Thermal radiation, Joule heating, and viscous dissipations concerning the Cattaneo-Christov thermosolutal flux have been introduced. An appropriate transition is applied to rationalize the substantially paired and nonlinear governing equations. Equations after similarity transformation are processed by the finite element method. The impression of different governing parameters on the governing systems in conjunction with entropy and Bejan number is displayed through graphs and tables. Graphs are drawn with an evaluation of general and hybrid nanofluids and different nanolayer thicknesses of nanoparticles. A similarity feature concerns existing literature with good promise. The thermal impact is more significant with the occurrence of Cattaneo-Christov heat flux and is further supported by thermal radiation and the Brinkman number. It has been found that Brinkman numbers boost the rate of heat transfer. Entropy generation is nonlinearly raised with advanced outcomes of radiation parameters, Brinkman number, and Reynolds number, while Bejan number shows the opposite behavior with respect to those parameters. The nanolayer thickness of the nanoparticles restricted the irreversibility phenomena of the system, and the same feature is supported by the Bejan number. [ABSTRACT FROM AUTHOR]

The MHD phase change heat transfer of a phase change substance in the presence of a uniform magnetic field is theoretically studied in a cavity. A fixed grid method associated with the enthalpy–porosity method is utilized. The governing equations are transformed into a non-dimensional form and solved using the finite element method. The impacts of the crucial parameters such as the Hartmann number and the inclination angle on the phase change process are investigated. It is found that any increase in Hartmann number and the inclination angle of the cavity leads to a decrease in the rate of the melting process. [ABSTRACT FROM PUBLISHER]

In this work, the effect of a variable spatial magnetic field on ferro-nanofluid flow and heat transfer in a double-sided lid-driven enclosure with a sinusoidal hot wall is investigated. The working fluid is a mixture of iron oxide (Fe3O4) nanoparticles and water and is referred to as a ferro-nanofluid. The control volume-based finite element method (CVFEM) is used to solve the governing equations in the stream function–vorticity formulation. In deriving the governing equations for this investigation, the effect of both ferro-hydrodynamics and magneto-hydrodynamics is taken into account. The numerical calculations are performed for different governing parameters namely; the Reynolds number, nanoparticle volume fraction, magnetic number (arising from Ferrohydrodynamics (FHD) consideration), and the Hartmann number (arising from Magnetohydrodynamics (MHD) consideration). The results show that an enhancement in heat transfer has a direct relationship with the Reynolds number and the Hartmann number, but it has an inverse relationship with the magnetic number. Also, it can be concluded that the Nusselt number increases with the increase of the nanoparticle volume fraction, magnetic number, and the Reynolds number while the opposite trend is observed for the Hartmann number. [ABSTRACT FROM AUTHOR]

In this study, mixed convection in a cavity that has a fluid and superposed porous medium with an adiabatic rotating cylinder is numerically investigated. The bottom horizontal wall is heated and the top horizontal wall is cooled while the remaining walls are assumed to be adiabatic. An adiabatic rotating cylinder is inserted inside the cavity. The governing equations are solved by the Galerkin weighted residual finite element method. The effects of Rayleigh number (between 103and 106), angular rotational speed of the cylinder (between 0 and 6,000), Darcy number (between 10−5and 10−2), cylinder sizes (betweenR = 0.1 andR = 0.3) and three different vertical locations of the cylinder on the fluid flow and heat transfers characteristics are numerically investigated. It is observed that the cylinder size has a profound effect on the local and averaged heat transfer. The local and averaged heat transfers generally increase and the convection is more effective in the upper half of the cavity as the Rayleigh number and Darcy number enhance. The averaged heat transfers increases with the cylinder size untilRa = 105. The averaged heat transfer increases almost linearly with the angular rotational velocity of the cylinder and the increase rate becomes higher as the cylinder size increases. The local and averaged heat transfers enhances/deteriorate as the cylinder approaches the upper/lower wall of the cavity. [ABSTRACT FROM AUTHOR]