Magneto-thermal convection in a porous circular cavity with Cassini oval obstacles: A numerical study on heat transfer enhancement

The stream function, temperature distribution, and natural convective heat transfer in a porous circular cavity with various obstacle geometries. The geometries considered include Horizontal Cassini Ovals (HCO), Vertical Cassini Ovals (VCO), and vertical Cassini ovals with two cylindrical obstacles. The system is subjected to a magnetic field at γ = 45°and a radiation parameter of Rd = 0.7. Water mixed with 5 % alumina nanoparticles (Al₂O₃ ) is used as the base fluid. The boundary conditions are consistent across all configurations, with the cavity surface maintained at a high temperature and the obstacles subjected to uniform heat flux (Dirichlet condition), while all surfaces adhere to a no-slip condition under a uniform magnetic field at 45 degrees. Results indicate that the circular cavity with a VCO obstacle shows the most significant reduction in stream function, decreasing by 48.9 % compared to the HCO, followed by configurations with two cylindrical barriers. The temperature increase is highest in the vertical Cassini oval geometry, rising by 498.6 % over the horizontal Cassini case. Additionally, this configuration achieves the maximum local Nusselt number in the cavity with a VCO and two cylindrical obstacles, highlighting superior heat transfer performance.