Computational fluid dynamics (CFD) is a branch of fluid mechanics that
uses numerical analysis and data structures to analyze and solve problems that
involve fluid flows. Computers are used to perform the calculations required
to simulate the free-stream flow of the fluid, and the interaction of the
fluid (liquids and gases) with surfaces defined by boundary conditions. With
high-speed supercomputers, better solutions can be achieved, and are often
required to solve the largest and most complex problems. Ongoing research
yields software that improves the accuracy and speed of complex simulation
scenarios such as transonic or turbulent flows. Initial validation of such
software is typically performed using experimental apparatus such as wind
tunnels.