Thermosolutal mixed convection in a lid-driven irregular hexagon cavity filled with MWCNT–MgO (15–85%)/CMC non-Newtonian hybrid nanofluid

Abstract

Mixed convection heat and mass transfer of a hybrid nanofluid in a lid-driven irregular hexagon cavity is numerically studied in this paper. The nanofluid is composed of the multi-walled carbon nanotube and the magnesium oxide (MgO) nanoparticles (15–85 vol%) dispersed in a non-Newtonian carboxymethyl cellulose-based fluid obeying the Ostwald–de Waele rheological model. The governing equations are solved numerically by means of the finite volume method and the SIMPLER algorithm to treat the velocity–pressure coupling. The study is performed for some relevant physical parameters: the Richardson number (Ri = 0.001–10), the power law index (n = 0.2–1.0), the buoyancy ratio (N = − 3 to + 3), and the total solid volume fraction (φ = 0.0–0.02). The obtained results are presented in terms of streamlines, isotherms, isoconcentrations, velocity profiles, and local and average Nusselt and Sherwood numbers. This work proves the significant impact of the quoted parameters on the hydrodynamic, thermal, and mass fields. Indeed, the flow structure is more sensitive to the power law index and the Richardson number variations. Moreover, heat and mass transfer are enhanced by the decline of the latter. Also, the addition of nanoparticles enhances heat transfer for the three convection modes especially for the dominant forced convection mode (Ri = 0.001) where the improvement reaches 14.42% for a power law index equal to 0.8. However, it improves mass transfer in the dominant forced convection but in mixed and dominant natural convection (Ri = 1, 10) as the buoyancy ratio equal to + 2 and + 3.