3060 CFX calculation force

2. In fluid mechanics, for the convenience of studying problems, the concept of incompressible fluid ground is introced. The so-called incompressible fluid is absolutely incompressible fluid. The actual fluid is compressible, but different fluid, its compressibility is very different, such as gas and liquid, the main difference lies in the size of its compressibility. For liquid, its compressibility is very small, which is a secondary factor affecting the flow and can be ignored. For gas, it can be compressed, and the compressibility is large. Therefore, in general engineering problems, gas is often treated as compressible fluid and liquid as incompressible fluid. But the fluidity of the gas is very large. As long as a small pressure difference is applied, the gas can flow quickly, and the density change caused by this pressure difference is very small. Therefore, the compressibility of the flowing gas can also be ignored

a fluid without any exclusivity is called an ideal fluid. Ideal fluid is a hypothetical model in fluid mechanics, which does not exist in practice. But in many practical engineering problems, the a-hysteresis of real fluid is very small, which can be ignored and can be simplified to ideal fluid.