Optimized radiative mixed convection of micropolar nanofluids in irregular porous enclosures with spatially nonuniform thermal and magnetic fields

The purpose of this study is to investigate heat transfer enhancement in a complex porous enclosure under local thermal and magnetic controls, considering thermal nonequilibrium between the fluid and solid matrix and the influence of micropolar nanofluid behavior. A numerical model is developed for an inclined porous enclosure with irregular wavy sidewalls, two nonfacing moving walls and an internally heated cylinder. The enclosure is partially subjected to a magnetic field and partial heating. The working fluid is a micropolar nanofluid, and additional effects such as chemical reaction, thermal radiation and internal heat generation/absorption are included. The governing equations are solved using the control volume method coupled with a novel point-in-polygon (PIP) technique to accurately identify irregular computational domains. Response surface methodology (RSM) is used to optimize the Nusselt numbers of both fluid and solid phases. The results show that enlarging the magnetic field region significantly suppresses flow circulation and microrotation, with an approximate reduction of 11.3% as the magnetic width increases from 0.2 to 0.8. Increasing the inner cylinder radius further obstructs shear flow, reducing circulation and microrotation by about 18.7%. For the fluid phase, optimal heat transfer is achieved at B = 0.2000, AB = 0.5808 and Re = 100, yielding a maximum predicted Nusselt number of 12.6621. This study introduces a combined partial magnetic–partial heating strategy in an irregular porous enclosure using a novel PIP-based numerical framework. The findings provide valuable insights for optimizing heat transfer in advanced thermal systems involving porous media and micropolar nanofluids.