Double-diffusive mixed convection and entropy generation of Fe3O4-CoFe2O4-water hybrid nanofluid in an enclosure with a heated wavy cylinder

The role of hybrid (ferrous ferric oxide Fe3O4-cobalt ferrite CoFe2O4-water) nanofluid and mixed convection double-diffusive features on a two-dimensional laminar flow inside an enclosure having a heated wavy cylinder is addressed in this work. The heated cylinder is positioned in the center of the enclosure and acts as a heat source. All the sides of the enclosure are regarded as cold and low in concentration, whereas the temperature and concentration at the edge of the cylinder are high. These temperature and concentration differences ensure the double diffusive natural convection within the enclosure; in contrast, the top side's left-to-right movement sustains the forced convection inside it. The governing equations are solved numerically using the finite element method (FEM). For the purpose of evaluating the dynamics of fluid, heat transfer, along with concentration distribution for a range of regulating parameters (Ri, p, Le, Br), a comprehensive parametric analysis is carried out. In addition, an in-depth examination of entropy formation resulting from fluid friction, heat transfer and mass transfer is performed. The findings of this study reveal that when p=0.02, the average Nusselt number (Nu) increases by 20.45%, 11.47% and 11.65% for Ri values of 0.01, 1 and 3 respectively compared to the base fluid water i.e., p=0.00. Simultaneously, average Sherwood number, (Sh) reduces by 2.19%, 3.26% and 3.46% respectively for same value of Ri. Moreover, it is also observed that for a fixed value of Ri the mass transfer rate decreases with increasing values of p, although the heat transfer rates increase correspondingly. Furthermore, when p=0.0, the total entropy generation resulting from all factors is 9.778 for Ri=0.1, however it is 36.344 for Ri=3.0. Consequently, when p=0.02, the value of total entropy generation is 11.11 at Ri =0.1 whereas it is 38.42 when Ri=3. The current study finds that to achieve maximum efficiency of the system and to limit entropy formation in mixed convection of hybrid nanofluid within a square enclosure with a wavy heat source, lower values of Richardson number (Ri) and nanoparticles volume percentage (p) are consistently advantageous. Two correlations are proposed for Nu and Sh, which are valid for 0_1 <= Ri <= 3, 1 <= Le <= 2 and 100 <= Re <= 400. The study's findings are crucial for contemporary industrial applications, particularly in the field of electronic equipment cooling.