Correlation function analysis of fiber networks: Implications for thermal conductivity

Transport properties of highly porous fiber structures are investigated. The fibers are assumed to be thin, but long, so that the number of interfiber connections along each fiber is large. We show that the effective conductivity of such structures can be found from the correlation length of the two-point correlation function of the local conductivities. The correlation function in the most interesting cases can be estimated from two-dimensional (2D) images of the structures. This means that the three-dimensional conductivity problem can be considered using 2D digital images of the structure. We apply this approach to analyze the parameters that determine the thermal conductivity of fiber structures.