Fluid

At present, the research and analysis methods of fluid mechanics are divided into three types: theoretical analysis, experimental research, and numerical calculation. The theoretical analysis method is based on studying the laws of fluid motion, establishing various simplified flow models, and forming various types of governing equations that describe the flow; under certain assumptions and conditions, through analytical derivation and calculation, the analytical solution or simple solution of the problem is obtained.

For a long time, experimental research has been the main research method in fluid dynamics. Its principle is to use the principle of relative motion to establish ground experimental facilities, such as water tunnels, water channels, wind tunnels, and shock tubes, to obtain relevant data. However, experimental research is generally completed under simulated conditions. Almost all ground experimental facilities cannot fully satisfy all similarity parameters and similarity law requirements. Moreover, in addition to wall effects, support interference, and measurement errors, experiments also face factors that are very difficult to simulate, such as the non-equilibrium effects of real gases in hypersonic flow. Therefore, experimental research is also subject to many limitations. Generally speaking, experimental research has a long cycle and high cost.

Computational Fluid Dynamics, abbreviated as CFD, is a specialized discipline that uses computers and numerical methods to solve fluid dynamics equations satisfying definite solutions, so as to obtain flow laws and solve flow problems. As a specialized discipline, computational fluid dynamics was roughly formed in the 1960s. Now CFD has penetrated into technical fields related to flow.