Purpose The nanofluid flow and heat transfer within a heat exchanger, with different thermal arrangements of internal active bodies, are investigated. Design/methodology/approach For the numerical simulations, the lattice Boltzmann method is utilized. The KKL model is used to predict the dynamic viscosity of CuO-water nanofluid. Furthermore, the Brownian method is taken account using this model. The influence of shapes of nanoparticles on the heat transfer performance is considered. Findings The results show that the platelet nanoparticles render higher average Nusselt number showing better heat transfer performance. In order to perform comprehensive analysis, the heatline visualization, local and total entropy generation, local and average Nusselt variation are employed. Originality/value The originality of this work is carrying out a comprehensive investigation of nanofluid flow and heat transfer during natural convection using lattice Boltzmann method and employing second law analysis and heatline visualization.

Purpose This paper aims to investigate the two-dimensional numerical modeling of fluid flow and heat transfer in a fluid channel. Design/methodology/approach The channel is filled with the CuO-water nanofluid. The KKL model is used to estimate the dynamic viscosity and considering Brownian motion. On the other hand, the influence of CuO nanoparticles’ shapes on the heat transfer rate is taken account in the simulations. The channel is included with several active pipes with hot and cold temperatures. Furthermore, the external curved and sinusoidal walls have cold and hot temperatures, respectively. Findings Three different tilt angles are considered with similar boundary and operating conditions. The Rayleigh numbers, solid volume fraction of CuO nanoparticles in the pure water and the tilt angles are the governing parameters. Different cases studies, such as streamlines, heat transfer rate, local and total entropy generation and heatlines, are analysed under influences of these governing parameters. Originality/value The originality of this work is investigation of fluid flow, heat transfer and entropy generation within a nanofluid filled channel using FVM.

Numerical investigation of the effects of magnetic field strength, thermal radiation, Joule heating, and viscous heating on a forced convective flow of a non-Newtonian, incompressible power law fluid in an axisymmetric stretching sheet with variable temperature wall is accomplished. The power law shear thinning viscosity-shear rate model for the anisotropic solutions and the Rosseland approximation for the thermal radiation through a highly absorbing medium are considered. The temperature dependent heat sources, Joule heating, and viscous heating are considered as the source terms in the energy balance. The non-dimensional boundary layer equations are solved numerically in terms of similarity variable. A parameter study on the Nusselt number, viscous components of entropy generation, and thermal components of entropy generation in fluid is performed as a function of thermal radiation parameter (0 to 2), Brinkman number (0 to 10), Prandtl number (0 to 10), Hartmann number (0 to 1), power law index (0 to 1), and heat source coefficient (0 to 0.1).