Transport Characteristics of Fluid Flow and Heat Transfer through Porous Media and Porous Obstacles for Various Configurations and Fluids

Abstract

The current thesis is aimed at the combined impact of distinct heat transfer models, variable thermophysical properties, and viscous dissipation effects for Newtonian fluids, hybrid nanofluids, and non-Newtonian fluids in permeable channels. We have also explored the flow and thermal properties of semi-circular obstacles/cylinders in confined and unconfined flow domains under the impact of distinct operating parameters. These research investigations could be used as a prototype for the development of various engineering applications. Initially, we aimed to investigate the combined impacts of the temperature-dependent thermal conductivities of the porous medium with the LTNE (local thermal non-equilibrium) model. A rectangular permeable channel with uniformly heated walls equipped with Newtonian fluid is taken into consideration. The Biot number is assumed to vary linearly, quadratically, and sinusoidally along with the channel height. The thermal conductivity variation parameter, the ratio of fluid and solid phase thermal conductivities, porosity, and heat generation parameters are taken as the governing parameters. The complex dependencies of these parameters on the temperature profiles and the Nusselt number are explored. Further, this work is extended by aggregating the viscous dissipation effects along with the non-Newtonian Casson fluid. The combined influences of the Brinkman number, Casson fluid parameter, and Darcy number on heat transfer characteristics are discussed in this chapter. Further, the unconfined air flow and heat transport across a semi-circular permeable/porous cylinder under LTE (local thermal equilibrium) condition is studied. The Darcy number and Reynolds number are considered as the main operating parameters. The collective impact of these parameters on the drag coefficient and local/average Nusselt number is evaluated and presented. Further, we moved our attention to the confined flow domains due to their wide applications in thermal engineering and bio-medical domains. From this viewpoint, the convective heat transfer from a porous semi-circular obstacle attached to a channel wall is numerically studied for LTE conditions. The Prandtl number, Darcy number, Reynolds number, porosity, and blockage ratio of the channel are taken as the operating parameters. The combined influences of all the above-mentioned parameters on the flow and thermal fields are presented. Furthermore, the significance of the simultaneous use of heaters and coolers in a permeable channel saturated with a hybrid nanofluid (Al2O3-CuO / Water) is studied. The influences of the shapes of heaters/coolers are explored by varying the shapes as circular and semi-circular with distinct orientations. The governing parameters are considered as Peclet number, Darcy number, porosity, and volume fraction of hybrid nanoparticles under the LTE model. The semi-circular heaters and coolers with curved faces towards the channel inlet and flat surfaces towards the bottom channel wall show higher heat transfer compared to other cases. Overall, this comprehensive research provides crucial insights into the intricate interplay of various operating parameters in multiple fluid dynamics and heat transfer scenarios, offering valuable knowledge for engineering applications and further scientific exploration