Numerical investigation of heat transfer and flow resistance in ellipsoidal Kelvin cell porous structures under inclined flow

Porous metallic structures such as Kelvin cells have attracted increasing attention due to their high surface-to-volume ratio and design flexibility, making them promising candidates for lightweight and efficient heat exchangers. While previous studies have primarily focused on isotropic or single-directional flow configurations, research on the thermohydraulic behavior of anisotropic Kelvin structures under oblique flow conditions—a common operating condition in practical applications—remains scarce. In this study, three-dimensional numerical simulations were conducted on ellipsoidal Kelvin cells with flow orientation angles ranging from 0° to 90°. The results indicate that the pressure drop generally increases with the tilt angle, rising by 87.7% at 90° compared to 0°, owing to enlarged frontal area, increased tortuosity, and stagnation effects. In contrast, the heat transfer coefficient rises significantly with angle and reaches its maximum at 60°, showing an enhancement of more than threefold relative to 0°. Analysis of velocity and temperature fields reveals that oblique jets and secondary flows disrupt boundary layers and enlarge fluid–solid contact areas, thereby strengthening convective mixing. The overall performance ratio (j/f) peaks at 60°, with an improvement of approximately 268%, confirming that moderate inclination provides the optimal balance between heat transfer enhancement and flow resistance. These findings fill a critical research gap and provide mechanistic insights and design guidance for optimizing anisotropic porous media heat exchangers.