Thermal and hydrodynamic study of mixed convection heat transfer of a nanofluid in an enclosure with unequal-sized baffles using the Lattice Boltzmann method

Considering the broad applications of the Lattice Boltzmann method (LBM) in solving thermal and hydrodynamic problems, the analysis of the mixed convection of nanofluid (NF) flow in a closed enclosure (ENC) is presented using this method. The ENC has three fixed walls and one movable one, and the magnetic field (MGF) influences the NF at the Hartmann numbers (Ha) of 0 to 40. The upper and lower walls of the ENC are cold and hot, respectively. There are five baffles on the hot wall that have different heights and the same temperature as the wall. The baffles on the side walls are taller, and the height of the baffles (HTB) is increased by moving towards the middle of the wall. The changes in the HTBs are from 0.3 to 0.1 in the shortest state and from 0.6 to 0.4 in the longest one. The results demonstrate that the enhancement in the Richardson number (Ri) weakens the vortex inside the ENC and reduces the Nusselt number (Nu). An increment in the HTBs weakens the vortex inside the ENC but enhances the value of the Nu on the upper wall due to the increase in the temperature of the NF inside the ENC. The enhancement of the Ha weakens the Ha vortex and reduces the heat transfer (HET) on both walls, which can be seen at all angles of the MGF. Enhancing the angle of the MGF also improves the HET rate in the ENC.

Automated summary

In this study, the mixed convection of nanofluid flow in a closed enclosure is analyzed using the Lattice Boltzmann method. The effects of the magnetic field and wall baffles on the flow and heat transfer are investigated. The results show that increasing the Richardson number weakens the vortex inside the enclosure and reduces the Nusselt number, while increasing the wall baffles enhances the Nusselt number on the upper wall but weakens the vortex inside. In addition, enhancing the Hartmann number weakens the vortex and reduces the heat transfer on both walls, and increasing the angle of the magnetic field improves the heat transfer rate in the enclosure.