LAVAL NOZZLE

Compressible Fluid Dynamics
Even elementary textbooks on fluid dynamics describe the flow of water through converging diverging nozzles. These nozzles usually have a contraction that accelerates the flow and forms a shock down-stream from the throat. The sudden pressure change that occurs across the shock can lead to the formation of vapor bubbles by a process called hydrodynamic cavitation. As the bubbles move down stream, and collapse, the vapor can internally reach very high temperatures and pressures. When the bubbles collapse their energy is often sufficient to erode metal surfaces often seen on the tips ship propellers. These phenomena are well known.

At present even much less is known about what is happening inside the bubbles when chemistry is involved especially if there are interactions at the interface with the surrounding fluid that in turn affects heat and mass transfer from the bubble vapor to the fluid.