Peristaltic pumping of magnetic nanofluids with thermal radiation and temperature-dependent viscosity effects: Modelling a solar magneto-biomimetic nanopump

Nanofluids have shown significant promise in the thermal enhancement of many industrial systems. They have been developed extensively in energy applications in recent years. Solar energy systems are one of the most promising renewables available to humanity and these are increasingly being redesigned to benefit from nanofluids. Most designs of solar collectors involve fixed (rigid) geometries which may be cylindrical, parabolic, tubular or flat-plate types. Modern developments in biomimetics have identified that deformable conduit structures may be beneficial for sustainable energy systems. Motivated by these aspects, in the current work we present a novel model for simulating a biomimetic peristaltic solar magnetohydrodynamic nanofluid-based pump. The working fluid is a magnetized nanofluid which comprises a base fluid containing suspended magnetic nano-particles. The novelty of the present work is the amalgamation of biomimetics (peristaltic propulsion), magnetohydrodynamics and nanofluid dynamics to produce a hybrid solar pump system model. Heat is transferred via distensibility of the conduit in the form of peristaltic thermal waves and buoyancy effects. An externally applied magnetic field achieves the necessary circuit design for generating Lorentzian magnetic body force in the fluid. A variable viscosity modification of the Buongiorno nanofluid model is employed which features thermophoretic body force and Brownian dynamic effects. To simulate solar loading conditions a thermal radiative flux model is also deployed. An asymmetric porous channel is investigated with multiple amplitudes and phases for the wall wavy motion. The channel also contains a homogenous, isotropic porous medium which is simulated with a modified Darcy model. Heat generation/absorption effects are also examined. The electrically-conducting nature of the nanofluid invokes magnetohydrodynamic effects. The moving boundary value problem is normalized and linearized using the lubrication approach. Analytical solutions are derived for axial velocity, temperature and nanoparticle volume fraction. Validation is conducted with Maple numerical quadrature. Furthermore, the salient features of pumping and trapping phenomena discourse briefly. The observations demonstrate promising features of the solar magnetohydrodynamic peristaltic nanofluid pump which may also be exploited in spacecraft applications, biological smart drug delivery etc. (C) 2018 Elsevier Ltd. All rights reserved.