Heat transfer models for porous media in porous-walled turbulent flows

In order to evaluate the validity of different heat transfer models in porous media under different conditions, this paper uses direct numerical simulation to investigate turbulent flow and heat transfer in channels with high porosity porous media layer. The incompressible Navier-Stokes equations and the temperature convection-diffusion equation are solved by the finite difference method in the fluid region out of the porous layer. The modified Darcy-Brinkman-Forchheimer model is used to describe the resistance of porous media with high porosity in the porous media layer. The local thermal equilibrium (LTE) model, the local thermal non-equilibrium (LTNE) model, and the ideal metal foams (IMF) model are used to calculate the temperature distribution in the porous media layer, respectively. We explore the effectiveness of heat transfer models for porous media under different Biot numbers and two types of fluid media, i.e., water or air, by analyzing and comparing the statistical characteristics of the obtained thermal fields. The results show that the LTE model cannot accurately predict the heat transfer problem in the porous media of metal foam, and its equivalent thermal conductivity underestimates the heat transfer capacity of the porous media layer because only the porosity is considered. The IMF model performs well in the case of a fluid medium with small heat capacity and can replace LTNE to describe the heat transfer in porous media. In contrast, it does not perform well in the case of a fluid medium with a large specific heat capacity; it is necessary to consider the heat capacity and the heat transfer ability between the two phases to modify the estimated solid phase temperature distribution.