Effects of patterns of wavy walls and SWCNTs-MWCNTs-based nanofluids on mixed convective heat transfer in a lid-driven enclosure containing elliptical block of various aspect ratio

In this study, heat transfer performance within a rectangular lid-driven containing an elliptical shaped block has been investigated for different boundary conditions. A wavy wall of cosine function at the bottom wall was added to the rectangle to enhance the heat transfer rate. Using base fluid inside the enclosure as the working fluid, the study also investigated single-walled carbon nanotubes (SWCNT) and multiple-walled carbon nanotubes (MWCNT)-incorporated nanoparticles. The finite element method (FEM) is used to solve governing equations that are based on the Boussinesq approximation. The findings are presented as different 2D graphs, isothermal contours, and a thorough computation of the Nusselt number based on the examination of several relevant non-dimensional values. The achieved results indicate that with the increase in Reynolds number and volume fraction, Nusselt number also increases. Also, SWCNT nanofluid provided greater Nusselt number in most of the cases. The usage of a wavy wall at the enclosure's bottom wall, which featured ellipses with varying aspect ratios (0.5, 1, 2, 4), was one of the novel aspects. The maximum achieved Nusselt number was 18.19 for an aspect ratio of 2. A maximum 157.57% enhancement of Nu was observed compared to recent relevant literature with the addition of CNT nanofluid and wavy wall in that particular geometry.