ARTICLE IN PRESS JID: JTICE [m5G;May 17, 2019;1:39] Journal of the Taiwan Institute of Chemical Engineers xxx (xxxx) xxx Contents lists available at ScienceDirect Journal of the Taiwan Institute of Chemical Engineers journal homepage: www.elsevier.com/locate/jtice Heat irreversibiility analysis for a couple stress fluid flow in an inclined channel with isothermal boundaries Samuel O. Adesanya a,b , Basma Souayeh c , Mohammad Rahimi-Gorji d,e , M.N. Khan f,∗ , O.G. Adeyemi g a Environmental Hydrodynamics Research, Department of mathematical Sciences, Redeemer’s University, Ede, Nigeria b Department of Mathematics, Vaal University of Technology, Vanderbijlpark, South Africa c Physics department, college of Science, King Faisal University, PO Box 380, Alahsa 31982, Saudi Arabia d Experimental Surgery Lab, Faculty of Medicine and Health Science, Ghent University, Ghent, Belgium e Biofluid, Tissue and Solid Mechanics for Medical Applications Lab (IBiTech- bioMMeda), Ghent University, Ghent, Belgium f Department of Mechanical and Industrial Engineering, College of Engineering, Majmaah University, Al-Majmaah 11952, Kingdom of Saudi Arabia g Department of Chemical Sciences, Redeemer’s University, Ede, Nigeria a r t i c l e i n f o Article history: Received 11 February 2019 Revised 3 April 2019 Accepted 26 April 2019 Available online xxx Keywords: Isothermal heating Couple stresses Second law Inclined channel a b s t r a c t Entropy generation in a fully developed couple stress fluid flow through an inclined channel is the focus of the present article. The steady flow of the non-Newtonian fluid via the inclined channel is assumed to be heated isothermally at the boundaries. The formulation of both the fluid flow and heat are based on hydrodynamics and thermodynamics laws. Exact solutions are constructed the dimensionless govern- ing equations. The accuracy of the two solutions are established by direct comparison with the limiting case previously obtained in the current literature. Solution profiles are also presented to demonstrate the effect of variations in the parameter values followed closely by extensive discussions. © 2019 Published by Elsevier B.V. on behalf of Taiwan Institute of Chemical Engineers. 1. Introduction The last few years have witnessed increasing studies on the entropy generation in gravity-aided flows through an inclined channel. The tilt in channel encourages the influence of the earth’s gravitational force and this configuration is closer to reality in a good number of applications in the physical science and engi- neering. Some of the landmark achievement in building a more realistic model can be seen in a recent work by Makinde and Gbolagade [1], the authors presented a thermodynamics analysis based on the gravity effect and a two dimensional heat distribu- tion. Havzali et al. [2] dealt with same problem with interest in the initial and entrance behavior of the channel. Baskaya et el. [3], considered the magnetic field effect on buoyancy and pressurized flow down an inclined channel. In the work of Abass et al. [4], the magnetized two-phased nanofluid slip flow experiencing thermal radiation was examined. The underlying fact about all the studies described above is the validity in the Newtonian class. There are ∗ Corresponding author. E-mail addresses: adesanyas@run.edu.ng (S.O. Adesanya), bsouayeh@kfu.edu.sa (B. Souayeh), mohammad.rahimigorji@ugent.be, m69.rahimi@yahoo.com (M. Rahimi-Gorji), mn.khan@mu.edu.sa (M.N. Khan), adeyemio@run.edu.ng (O.G. Adeyemi). some research in this field which can be very useful and applicable in future researches and industries [5–23]. The main concern here is to extend the study to the non- Newtonian class where the effect of body couples and couple stresses can be captured, especially for commonly used indus- trial fluids where inclusion of tiny additives plays a dominant role. The couple stress model has been used recently in de- scribing flow properties several fluids. For instance, Hayat et al. [24] implemented the model for a reacting three-dimensional fluid flow experiencing magnetic field. Reddy et al. [25] utilized the approach for fluids with temperature dependent density, Hayat et al. [26] presented the homotopy series solution to the develop- ing three-dimensional flow endowed with Cattaneo–Christov con- dition. The non-Newtonian model was used to describe peristaltic flow in the work of Ramesh and Devakar [27] while the constitu- tive model was used for blood flow analysis in [28]. In short, the literature is unexhaustive on the theory and application of cou- ple stresses. In the current study, a simple generalization of the study in [1] is presented that can describe a wider range of non- Newtonian fluids like the blood, pharmaceutical mixtures, espe- cially lubricants used over a long period of time under intense heat and other fluid that flows steadily through an inclined chan- nel with isothermal heating which has not be done in previous https://doi.org/10.1016/j.jtice.2019.04.052 1876-1070/© 2019 Published by Elsevier B.V. on behalf of Taiwan Institute of Chemical Engineers. Please cite this article as: S.O. Adesanya, B. Souayeh and M. Rahimi-Gorji et al., Heat irreversibiility analysis for a couple stress fluid flow in an inclined channel with isothermal boundaries, Journal of the Taiwan Institute of Chemical Engineers, https://doi.org/10.1016/j.jtice. 2019.04.052