Diffusion Mass Transfer In Fluid Systems Cussler } \), where \( J \) is the diffusion flux, \( D \) the diffusion coefficient, and \( \frac{dC}{dx} \) the concentration gradient. Fick’s Second Law: Addresses the temporal change in concentration, accounting 2. for how diffusion evolves over time. Cussler’s analysis often extends these law Nov 14, 2025 Read more →