2D sections of the first component of the flux field J₁, obtained by FFT method on the Boolean models, with macroscopic concentration gradient 〈−∇c〉 = (1, 0, 0), with convergence criteria L1-norms difference of E between two iterations less than 10⁻⁶. The microstructure volume is 300 × 300 × 300 nm³ (909³ voxels at resolution 0.33 nm per voxel). The same macroscopic concentration gradient and the same convergence criteria are applied for all remaining computations of this work. a) sphere, b) cubic prism, c) platelet-like prism, d) rod-like prism.