Darcy–Forchheimer natural convection flow of SWCNTs-EG-based nanofluid along a complex roughened surface

The study of heat transfer in natural convection flow of nanofluid (mixture of SWCNTs and ethylene glycol fluid) through a complex roughened surface saturated in a porous medium is investigated. The governing equations in terms of nonlinear PDEs are derived using Darcy–Forchheimer and Tiwari and Das models and made dimensionless using transformation. A finite difference scheme with backward and central differences approximations is used to conduct numerical solution. Recently, researchers have focused on the use of roughened surfaces or suspension of nanoparticles in base fluid to improve heat transfer rate. The objective of this study is to quantify the increase in heat transfer rate due to complex roughened surface and nanofluid. The results reveal that total heat transfer rate raises higher in nanofluid as compared to largest amplitude of harmonic wave. The absolute value of drag coefficient and rate of total heat transfer grow by increasing the value of Darcy number. Near the leading edge, the total heat transfer rate declines up-to certain node value which is 0.2125 and 0.2071 in the absence and presence of nanofluid and increases away from these node values. Streams slices and isotherm lines expand in case of largest amplitude of harmonic wave and nanofluid.