Unsteady Heat and Mass Transfer Mechanisms in Carreau Nanofluid Flow

Abstract

This thesis reports on results of the research project on the mathematical modeling and numerical study of a non-Newtonian fluid. Particularly, the subject matter of tIns thesis concerns with the unsteady flow, heat and mass transfer of Carreau fluid in the presence of nanoparticles. One of the most important developments in the recent decades is the vast utilization of nanofluids in the engineering applications. The main aim of this research was the study of Carreau nanofluid flow using the Buongiorno's model that incorporates the effects of thermophoresis and Brownian motion. We focus on different types of flow phenomena over moving surfaces via numerical approach. The problems studied here incorporate the effects of magnetic field, heat generation/absorption, suction/injection, melting phenomenon, variable thermal conductivity and nonlinear thermal radiation in different geometries. The governing partial differential equations are altered into ordinary differential equations by adopting suitable transforming variables and then solved numerically by utilizing two different numerical methods namely shooting RK45 and bvp4c Matlab package. In special cases, our numerical results are validated with previously published data and achleved to be in excellent agreement. The present thesis concentrates on the unsteady flows of non-Newtonian Carreau rheological model. The problem considered here include the unsteady flow and heat transfer to Carreau fluid, the study of Carreau nanofluid in unsteady heat and mass transfer, unsteady wedge flow of Carreau nanofluid, unsteady analysis of melting heat transfer in Carreau nanofluid with heat generation/absorption, unsteady flow of Carreau nanofluid in expanding/contracting cylinder, stagnation point flow in Carreau nanofluid in expanding/contracting cylinder, unsteady analysis of Carreau nanofluid past radially stretchlng surface. To gauge and establish the physical aspects of the obtained results, a few of the velocity, temperature and concentration profiles are displayed through figures with detailed discussion. Additionally, the local skin friction, Nusselt and Sherwood numbers are calculated in tabular form. One key observation is that the temperature field enhances for growing values of thermophoresis and Brownian motion parameters. Additionally, temperature as well as nanoparticles concentration fields depreciate by increasing the melting parameter in both shear thickening and shear thinning liquids. Furthermore, temperature gradient is a growing function of the wedge angle parameter. However, temperature ratio parameter results in an enhancement in the temperature and its related thermal boundary layer thickness.