Propagation of Pressure Waves

Gas and liquid are termed fluid because they can flow with changes to their shape. Most flows occurring in our daily life are not significantly influenced by compressibility. However, in high-speed flows and/or when velocity or pressure rapidly varies, compressibility is significant. The compression and expansion of a fluid, which correspond to variations of its density, lead to the propagation of pressure waves. In compressible fluid dynamics, we study the relationship between pressure-wave propagation and its impact on flow properties. In this chapter, we will learn the basic concepts of pressure-wave propagation through several examples.