Darcy Flow

Physics: Darcy's law: q = -K/μ · ∇P, where q is the Darcy flux (m/s), K is permeability (m²), μ is dynamic viscosity, and ∇P is the pressure gradient. The volumetric flow rate Q = KA·ΔP/(μL). Permeability ranges from 10⁻²⁰ m² (granite) to 10⁻⁹ m² (gravel). Valid for Re < 1 (creeping flow); Forchheimer correction needed at higher Re. Governs aquifer hydrology, oil reservoir production, and filtration.