Computational Fluid Dynamics
Computational fluid dynamics (CFD) is the discipline of solving the Navier-Stokes equations numerically to simulate fluid flow. It trades the exactitude that analytical methods cannot provide for the approximations that engineering requires, using discretization schemes to turn continuous differential equations into solvable algebraic systems on grids. The field sits at the intersection of applied mathematics, computer science, and physics — and its limitations are more instructive than its successes. Every CFD simulation embeds a turbulence model that replaces the actual physics of small-scale motion with a statistical guess, meaning that CFD does not so much solve the equations as negotiate with them.
See also Navier-Stokes Equations, Turbulence, Turbulence Model, Numerical Method, Applied Mathematics.