MHD natural convection in inclined wavy annulus utilizing hybrid nanofluid with discrete wavy coolers

Abstract

In the present framework, the combined effect of magnetic field (Hartmann number, Ha), angle of inclination $$(\alpha )$$ , nanoparticle volume fraction $$(\chi )$$ , number of oscillations (N) and aspect ratio (AR) is investigated for natural convective heat transfer analysis containing hybrid nanofluid suspension ( $$\hbox {Al}_2\hbox {O}_3$$ and Cu) in wavy annulus having circular heater in the center and discrete coolers on the wavy walls. The homogeneous hybrid nanoliquid (0.1% of $$\hbox {Al}_2\hbox {O}_3{-}\hbox {Cu}/\hbox {water}$$ ) model with fitted correlations of viscosity and thermal conductivity from the experimental data is used, and results are evaluated for different ranges of controlling parameters: Rayleigh numbers ( $$\hbox {Ra}=10^3$$ – $$10^6$$ ), Hartmann number (Ha $$=$$ 0–50), aspect ratio (AR (D/H) = 0.2–0.6), number of oscillations or undulation parameter ( $$N=2$$ –8) with fixed amplitude ( $$a\,=\,0.02$$ ), angle of inclination ( $$\alpha =0{^{\circ }}$$ – $$135{^{\circ }}$$ ) and nanoparticle volume fraction ( $$\chi =0$$ –0.02) using Galerkin finite element method (GFEM) with triangular mesh. The mesh grid independency test has been conducted with different meshes (degree of freedoms), and a refined mesh with domain elements $$=$$ 21,662, boundary elements $$=$$ 884 and degree of freedoms (DOFs) $$=$$ 179,703 has been selected for entire computations. The average Nusselt number is evaluated as a function of Ra, $$\alpha$$ and N for different parametric ranges of $$\chi$$ , Ha and AR, respectively. The average heat transfer follows as zigzag pattern with increment in waviness (undulation parameter), and it has a minimum value for inclination angle $$=\pi /2$$ . With high Rayleigh number ( $$\hbox {Ra}>10^5$$ ), the average Nusselt number shows opposite trend with hybrid nanoparticle concentration. This type of research can be used in the design of an appropriate nanofluid-based cooling system for electronic components to ensure effective operational conditions.