Heat transfer analysis of CNTs-water nanofluid flow between nonparallel plates: Approximate solutions

Approximate solutions are given to investigate the problem of heat transfer and flow of a nanofluid between two nonparallel plates. Two different types of carbon nanotube (CNT) nanoparticles, namely functionalized single-walled carbon nanotubes and functionalized multi-walled carbon nanotubes are considered with water as the base fluid. The chemical functionalization is attributed to the attachment of the covalent bond of functional groups onto carbon nanotubes. Using the appropriate similarity variables, the model partial differential equations are transformed into ordinary differential equations and tackled analytically via the homotopy perturbation method. Comparison of the obtained results is carried out with those obtained by the previously published in the literature as well as the Runge–Kutta–Fehlberg method and an excellent agreement is achieved. The effects of various emerging parameters on nanofluid velocity, temperature, skin friction coefficient, and Nusselt number are illustrated graphically and comprehensively discussed.