Eur. Phys. J. Plus (2018) 133: 329
https://doi.org/10.1140/epjp/i2018-12093-y

Regular Article

Entropy generation optimization and activation energy in nonlinear mixed convection flow of a tangent hyperbolic nanofluid

¹ Department of Mathematics, Quaid-I-Azam University 45320, 44000, Islamabad, Pakistan
² Department of Basic Sciences, University of Engineering & Technology, Peshawar, Pakistan
³ Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Faculty of Science, King Abdulaziz University, P. O. Box 80207, 21589, Jeddah, Saudi Arabia
⁴ Heriot-Watt University, Edinburgh Campus, EH14 4AS, Edinburgh, UK

^* e-mail: mk42@hw.ac.uk

Received: 11 April 2018
Accepted: 5 June 2018
Published online: 21 August 2018

Abstract

This study addresses the stagnation flow of a hyperbolic tangent nanofluid over a stretching sheet. Nonlinear convection, Brownian motion and thermophoresis are studied. In addition the nonlinear thermal radiation, dissipation and heat generation/absorption are taken into account. To characterize the effect of the Arrhenius activation energy, a binary chemical reaction is considered. The total entropy generation rate is calculated and discussed as per the criteria of the second law of thermodynamics. Convergent solutions for the resulting nonlinear systems are derived and the effects of embedded parameters of interest on velocity, concentration, temperature and entropy are examined. The skin friction coefficient and Nusselt and Sherwood numbers are numerically discussed.