Inverse Estimation of the Flow Resistivity Tensor of Open-Cell Foams from Experimental Data and Darcy’s Flow Simulations

The flow resistivity tensor, which is the inverse of the viscous permeability tensor, is one of the most important material properties for the acoustic performance of open cell foams, used in acoustic treatments. Due to the manufacturing processes, these foams are most often geometrically anisotropic. This paper discusses the estimation of the flow resistivity tensor using an improvement of a previously published method by Göransson, Guastavino et al. First, flow measurements were performed for different orientations of a cubic porous sample. The modelling of the flow resistivity tensor is centred around a three-dimensional Darcy's law model in COMSOL Earth Science Module, representing the experimental set up. The simulations are performed within an optimisation loop, to determine which flow resistivity tensor gives the best fit of the simulation results to the experimental data, of volume flow and pressure drop between the inlets and outlets. The discussion focuses on the optimiser, the use of COMSOL Multiphysics and the identified flow resistivity tensor of a Melamine sample.