Nu–Ra–Fo correlations for transient free convection in 2D convective diode cavities with discrete heat sources

This work allows to quantify the transient natural-convection heat transfer taking place in air-filled convective diode cavities. The results are presented in terms of Nusselt–Rayleigh–Fourier numbers correlations. They are valid for the specific configuration of the hot wall that consists of three horizontal, isothermal discrete bands separated by two adiabatic ones of the same dimensions. The channel that connects the hot and cold walls is adiabatic and is inclined between −60° and +60° with respect to the horizontal. The correlations proposed are obtained from numerical results based on the finite volume method and are validated by measurements. They complement those obtained in a previous work for steady state and Rayleigh number in the range 1.84 × 105 ⩽ Ra ⩽ 1.70 × 109, which make them suitable for applications in several industrial sectors.