Shape effect of nanosize particles in unsteady mixed convection flow of nanofluid over disk with entropy generation

Abstract

The aim of this paper is to study the different shapes of nanoparticles on mixed convective steady flow over a rotating disk. For nanofluid, the copper nanoparticles of disk, cylindrical, and spherical shapes of different sizes and water as base fluid are considered. The physical problem is first modeled and then the governing equations are transformed into nonlinear ordinary differential equations. These equations are dimensionless using geometrical and physical flowfield-dependent parameters and solved analytically. A very good agreement is observed between the obtained results of the current study and previously published study in limiting cases. The shape effects on velocity profiles in radial, tangential, axial directions, and temperature distribution are displayed graphically with the reflection of specific range of nanolayer thickness and its conductivity. In addition, irreversibility due to heat and fluid friction is investigated that supports the heat transfer enhancement in renewable energy systems and industrial thermal management. For the analysis of the averaged entropy generation number, the results are shown in pie charts and tablet form. It is evident from the study that proper choice of nanoparticles will be helpful in controlling velocity and heat transfer. It is also observed that irreversibility process can be reduced by using nanoparticles, especially the spherical particles.