Thermal fluid dynamic analysis of 3D printable metal foams

This study presents a numerical investigation of the pressure drop per unit length and the heat transfer coefficient in 3D printable open-cell metal foams. The ultimate goal is to derive new correlations that allow the prediction of the thermal fluid dynamic performance of the cell using the topological characteristics of the cells and the fluid conditions. The data set included 18 different cell types, each with six different elongations along the flow direction and five porosities, resulting in a total of 540 simulations. The geometries were defined by using the coordinates of the vertices of their ligaments and a connectivity matrix that stored the connections between the different points. The numerical simulations were carried out in laminar flow regime with a constant heat flux boundary condition and air as the working fluid. The flow patterns within the different cells were analysed to understand the mechanism behind the results obtained. The simulations that showed unsteady convergence were discarded. The remaining results produced a reduced data set with 300 simulations. This data set was then used to derive new correlations for the friction factor, the Nusselt number and the area goodness factor. A simple Nusselt number - Reynolds number correlation was derived using the least squares method, while more complex equations were obtained using the symbolic regression method. The correlations were validated using experimental and numerical data available in the literature. The data used for the validation process were based on porous structures with cell geometries that were not included in the initial data set. The final correlations provided an overview of the effect of the geometric parameters of the cell on the thermal fluid performance of the metal foam.