The Role of Periodic Mixing on Thermal Energy Extraction From an L-Shaped Heater Covered by Porous Layer

In this numerical study, a technical solution is proposed to maximize heat transfer within a square cavity by integrating an L-shaped porous layer in the lower right part of the cavity, covering an L-shaped heat sink heated to a set temperature. Additionally, a thin bar undergoes a periodic sinusoidal motion with an amplitude of V_bar and a period of ω_bar. The finite element method is used to solve the governing dimensionless nonlinear equations, with a mesh test supported by numerical and experimental validations. The study focuses on the effects of bar displacement amplitude (V_bar = 0.1–0.4), displacement period (ω_bar = 1/3–1), Reynolds number (Re = 50, 100, and 200), Darcy number (Da = 10⁻² and 10⁻⁴), and porosity (ε = 0.75–0.95) on the average Nusselt number, streamlines, and isotherms distribution. The numerical results show that increasing the bar displacement amplitude, Darcy number, and Reynolds number can significantly enhance the overall heat transfer, while an increase in the porosity of the porous medium has the opposite effect. The bar's sinusoidal motion and the porous medium's presence alter the flow dynamics within the cavity and directly influence heat transfer.