The GDL microstructures were generated using the FiberGeo module within the Geodict 66 software. The microstructures were stochastically generated and digitally characterized along with other properties in the context of our previous work . In this work, geometric tortuosity was not used to train any ML model. The microstructures there consisted of infinite/ circular carbon fibers with the specified solid volume percentage (%). We used it here with domain sizes 2000 μm × 200 μm × thickness μm and 1000 μm × 1000 μm × thickness μm with a voxel length of 1 μm. These domain sizes datasets are denoted as GDL200 and GDL1000, respectively. Our target property in this case is the geometric tortuosity, which digital characterization in the GDL200 dataset takes 65% less computational time than in the GDL1000 one. The input parameters to compute this target are the fiber diameter, the fiber concentration, the binder concentration, the thickness, and the compression.