Thermal performance of double-diffusive nano-encapsulated phase change materials in a porous concentric octagonal annulus under the impact of periodic magnetic field and activation energy

Nano-encapsulated phase change materials (NEPCMs) have attracted considerable interest recently because of their distinctive capacity to improve the thermal characteristics and overall effectiveness of phase change materials (PCMs). The present work investigates the flow of NEPCMs in the octagonal annulus under the impact of a periodic magnetic field. The dimensionless form of the governing equations is discretized with the finite element method and the associated discrete nonlinear systems are handled by employing the adaptive Newton's method. The Gaussian elimination procedure has been adopted for the linear sub-problems. It has been observed that at a cavity aspect ratio of (AR=0.35), an enhancements in both the Nuavg and Shavg are observed. particularly, an increase in the buoyancy ratio N from N=0 to N=1, leads to an augmentation of 31.7% in the average Nusselt number and a substantial improvement of 33.9% in the average Sherwood number.