Transport Percolation Diagram of Composite Medium Predicted by Microscopically Calibrated Lattice Model and Data-Driven Analysis

Electrical conduction and thermal conduction in homogeneous composites are often considered analogous macroscopic transport phenomena due to the identical mathematical formulation of Ohm’s law and Fourier’s law. However, this analogy breaks down in multiphase composites, where their behaviors can differ markedly. Experimental evidence shows that electrical percolation is often readily observed, whereas thermal percolation remains elusive and even debated. To address this, we develop a simplified yet carefully calibrated lattice model to efficiently simulate the macroscopic transport behavior of composite material and generate large datasets across a wide transport parameter space. Data-driven analysis reveals a boundary separating percolating and non-percolating regimes, leading to a transport percolation diagram that distinguishes “easy” and “hard” percolation. Additionally, a numerical singularity associated with interfacial area is identified in the percolation-allowed regime, indicating that the occurrence of numerical instability might be used as the criterion for the presence of transport percolation.