Heat transfer of TiO2 − EG nanoliquid with active and passive control of nanoparticles subject to nonlinear Boussinesq approximation

Abstract

In this study, the buoyancy-driven two-dimensional flow of a nanoliquid past a vertical plate subject to quadratic Rosseland thermal radiation and quadratic thermal convection (quadratic Boussinesq approximation) is investigated. The working liquid is ethylene glycol containing titania nanoparticles. The consequences of aggregation of nanoparticles are included using the modified Maxwell-Bruggeman and Krieger-Dougherty models for thermal conductivity and viscosity respectively. The analysis is performed under active and passive control of nanoparticles (NPs). To simulate the nanoliquid, the modified Buongiorno model is used which includes effective thermophysical properties and two significant slip mechanisms (nanoparticle random motion and thermophoresis). The phenomenon of physical flow is demonstrated with the help of a partial differential equation (PDE) system that uses conservation laws and the thermophysical properties of nanoparticles. Nonlinear PDEs related to the nanoliquid heat transport are transformed into ordinary two-point BVP (boundary value problem)and the obtained system has been solved numerically. It is found that the nanoparticle aggregation and quadratic thermal radiation aspects enhance the temperature field. Furthermore, the quadratic Boussinesq approximation aspect was found to hasten the heat transport rate at the plate.