Generation of entropy during forced convection of heat in nanofluid stagnation-point flows over a cylinder embedded in porous media

Sina Rezaei Gomari, Rasool Alizadeh, Ahmad Alizadeh, Nader Karimi

Research output: Contribution to journalArticlepeer-review

Abstract

Thermodynamics and heat transfer processes during impingement of a nanofluid flow upon a cylinder with constant surface temperature and embedded in porous media are investigated. The surface of the cylinder can feature uniform or non-uniform transpiration and is hotter than the incoming nanofluid flow. Appropriate similarity parameters are employed to reduce the three-dimensional governing equations of nanofluid motion and heat transfer in porous media to simpler equations solvable through using a finite difference scheme. The numerical solutions of these equations reveal the flow velocity and temperature fields as well as the Nusselt number and induced shear stress. These are then used to calculate the rate of entropy generation within the system by viscous and heat transfer irreversibilities. It is demonstrated that changes in the concentration of nanoparticles result in the variation of thermal and hydrodynamic boundary layers and hence can modify the Nusselt number and entropy generation considerably. However, the shear stress on the surface of the cylinder is observed to be less affected by the variations in the concentration of nanoparticles. Further, the Reynolds number of the impinging nanofluid flow and the functional form of transpiration are shown to have significant effects upon the Nusselt number and entropy generation. In particular, it is argued that the influences of Reynolds number on the boundary layer thickness can majorly modify the level of irreversibility and the value of Bejan number.
Original languageEnglish
Pages (from-to)647-673
Number of pages27
JournalNumerical Heat Transfer; Part A: Applications
Volume75
Issue number10
Early online date6 Jun 2019
Publication statusE-pub ahead of print - 6 Jun 2019

Fingerprint Dive into the research topics of 'Generation of entropy during forced convection of heat in nanofluid stagnation-point flows over a cylinder embedded in porous media'. Together they form a unique fingerprint.

Cite this