CFD

Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical methods and algorithms to analyze and solve problems involving fluid flows. CFD aims to predict velocity, pressure, temperature, and other flow characteristics by solving the governing equations of fluid motion on a computer. It is widely used in engineering design, analysis, and research.

The core of CFD is the Navier-Stokes equations, including conservation of mass, momentum, and energy. Depending on the problem, flows may be treated as incompressible or compressible, Newtonian or non-Newtonian, and may involve heat transfer or multi-phase phenomena. The equations are solved numerically after discretization and application of boundary conditions.

Common numerical methods include the finite volume method, finite element method, and finite difference method. The finite volume method is widely used for its conservative properties. Solutions require a mesh that represents the geometry and a time-stepping strategy for transient cases.

Turbulence modeling is a major aspect of CFD. Approaches such as Reynolds-averaged Navier–Stokes (RANS), large-eddy simulation (LES), and direct numerical simulation (DNS) balance accuracy and cost. Wall modeling and subgrid-scale models are often employed for complex flows near surfaces.

Validation and verification are essential in CFD. Verification assesses numerical accuracy, while validation compares simulations with experimental data. Grid refinement studies and benchmarking help establish credibility.

Applications span aerospace, automotive, energy systems, civil engineering, and biomedical engineering, including aerodynamic design, heat exchangers, combustion, and environmental flow studies. Limitations include model assumptions, numerical errors, and high computational costs, which require careful study and interpretation.