Entropy generation in MHD Maxwell nanofluid flow with variable thermal conductivity, thermal radiation, slip conditions, and heat source

Asim Aziz,Moniba Shams

doi:10.1063/1.5129569

Abstract

It is important to study heat transfer processes due to fluid flow in the context of entropy because the efficiency of such systems depends on reduction in entropy generation. Moreover, there is a need to develop mechanisms to control entropy generation in thermal systems. In this work, we study volumetric entropy generation rate in electrically conducting Maxwell nanofluid over a penetrable stretching sheet with variable thermal conductivity, velocity slip conditions, thermal radiation, and internal heat source effect. The governing equations of flow, heat transfer, and entropy generation have been abridged under the suppositions of boundary layer approximations and low Reynolds numbers. Solutions to the governing system of partial differential equations are carried out by transforming them into the system of ordinary differential equations using suitable similarity transformations. The resultant system is then solved numerically using a shooting technique along with the fourth order RK method. Numerical computations are carried out for water based Cu-water and Al2O3-water nanofluids. Corporeal topographies of velocity, temperature, entropy generation, Bejan number, skin friction coefficient, and Nusselt number are presented. The impact of important physical parameters are discussed through graphs and tables.

Highlights

The study of heat transfer due to fluid flow is essential for systems that retain heat from external sources and transfer it to fluid
Sithole et al.34 discussed chemical reactions on second grade nanofluid over a heated stretching sheet with nonlinear thermal radiation
To find solutions of the boundary value problem (2)–(6) together with Eqs. (7)–(9), initially a similarity transformation technique is applied. This results in a system of coupled nonlinear ordinary differential equations

Summary

INTRODUCTION

The study of heat transfer due to fluid flow is essential for systems that retain heat from external sources and transfer it to fluid. Thermal collectors, extraction of geothermal power, hydraulic breaks, heat exchangers, cooling of microchips, food processing, glass manufacturing, heat pipes, and solar water heating These applications led scientists and researchers to study heat transfer and fluid flow, considering different flow geometries, interface conditions, types of operating fluids, Newtonian and non-Newtonian fluid models, effect of external forces, variable thermophysical properties, velocities of bounding surfaces, and use of nanofluids as operating fluids.. Shen et al. introduced the Cattaneo-Christov heat flux model for flow and heat transfer of Maxwell viscoelastic nanofluid over a vertical sheet with natural convection They considered five different types of nanoparticle shapes including sphere, tetrahedron, hexahedron, lamina, and column. Sithole et al. discussed chemical reactions on second grade nanofluid over a heated stretching sheet with nonlinear thermal radiation They have used the spectral linearization method for entropy analysis and showed that for higher values of Hartmann, Reynolds, and Brinkman numbers. The properties of flow and heat transfer are studied in addition to entropy generation analysis

BASIC EQUATIONS AND FORMULATION

SIMILARITY REDUCTIONS AND ENTROPY ANALYSIS

Entropy analysis

NUMERICAL RESULTS AND DISCUSSION

CONCLUSION

Methods