Electronic edition ISSN 1574-0579

Entropy generation in unsteady MHD Hartmann--Couette hybrid nanofluid flow through a Darcian channel

V. Savanur¹ - S. K. C. N. Joshi¹ - S. Kolasani²

¹ Department of Mathematics, CMR University, Bangalore, 562149, Karnataka, India
² Department of Mathematics, Ballari Institute of Technology and Management, Ballari, 583105, Karnataka, India

Abstract
This paper studies unsteady magnetohydrodynamic Hartmann-Couette flow of a Cu-Al2O3/ water hybrid nanofluid in a Darcian channel with Hall current and ion-slip, extending a previous isothermal, momentum-only analysis by considering heat transfer, entropy generation, and a neural-network surrogate model. The momentum field is obtained by the Laplace transform method and cross-checked against an independently coded Crank--Nicolson finite-difference scheme. The coupled energy equation, which includes viscous dissipation, Joule heating and Rosseland radiation, is solved by the same finite-difference scheme under isothermal and ramped thermal boundary conditions. Entropy generation and the Bejan number are evaluated from the resulting fields, and a feedforward artificial neural network is trained to approximate shear stress, Nusselt number and entropy generation across the parameter space. The results show that stronger Hall coupling and greater hybrid-nanoparticle loading intensify the primary flow, the ramped thermal condition keeps near-wall temperatures lower than the isothermal case, a larger Hartmann number decreases total entropy generation while raising the Bejan number, and irreversibility is friction/Joule-dominated near the moving plate but heat-transfer-dominated toward the channel mid-plane. Tables 3, Figs 15, Refs 32.