Impact of five obstacles with constant temperatures on the mixed convection flow of water/copper nanofluid in a rectangular cavity with a magnetic field

Abstract

In this research, we conduct a computational investigation into the mixed convection flow of copper/water nanofluids (NFs) within a rectangular cavity, utilizing the Lattice Boltzmann Method (LBM). The cavity is uniquely configured with five high-temperature obstructions (HOBs), and we vary their dimensions and positions to evaluate Nusselt numbers (Nu) across a range of Richardson numbers (Ri). The three walls of the cavity, excluding the moveable top wall, are thermally insulated, while the latter is maintained at a lower temperature. A constant magnetic field (MCF) exerts influence within the cavity, with Ri spanning from 0.01 to 100, HOBs ranging from 0.1 to 0.5, and HOBs at the bottom wall spanning from 0.25 to 0.4. This numerical investigation is executed using a customized in-house code, focusing on examining heat transfer (HTR) dynamics within the cavity. Our findings reveal that augmenting the height of the HOBs and positioning them closer to the cold wall significantly enhances the average Nusselt number (Nuav). Conversely, an increase in Ri leads to a reduction in Nuav on the cold wall. Specifically, the most notable enhancement, with a 66.7 % increase in Nuav, occurs at Ri = 0.01 when HOBs are elevated from 0.1 to 0.5. On the other hand, an increment in Ri from 0.01 to 100 results in a 79.4 % reduction in Nuav. Furthermore, elevating the HOBs from 0.25 to 0.4 produces a substantial 44.3 % increase in Nuav.