Amplitude and Period Effect on Heat Transfer in an Enclosure with Sinusoidal Heating from Below Using Lattice Boltzmann Method

This work presents a simulation of the phenomena of natural convection in an enclosure with a variable heating regime by the lattice Boltzmann method (LBM). We consider a square enclosure of side H filled with air (Pr = 0.71) and heated from below, with a hot portion of length L = 0.8 H, by imposing a sinusoidal temperature. The unheated segments of the bottom wall are treated as adiabatic, and one of the vertical walls features a cold region, while the remaining walls remain adiabatic. The outcomes of the two-dimensional (2D) problem are depicted through isotherms, streamlines, the temperature evolution within the enclosure, and the Nusselt number. These visualizations span various amplitude values “a” in the interval [0.2, 0.8], and of the period T₀ for Ra = 10⁷. The amplitude and period effect on the results is evaluated and discussed. The amplitude of the temperature at the heart of the enclosure increases with the increase in amplitude. This also increases with the period (T₀) of the imposed temperature, something that is not observable on the global Nusselt number.