Scientists at the University of Cambridge (UK) have explained a phenomenon called a hydraulic jump, which is expressed in a sharp increase in water level as its speed decreases. This phenomenon is observed in household sinks and bathtubs, when a jet of water hits a flat surface and is quickly thrown to the sides, where a standing shock wave occurs. This was announced in a press release on Phys.org.
This phenomenon was first described by Leonardo da Vinci about 500 years ago, but since then scientists have not known the exact mechanism of its occurrence. It was believed that the hydraulic jump is in part created by the gravity of the Earth.
However, in the new work, scientists, observing the behavior of water when gushing jets hit a surface raised at various angles, came to the conclusion that the phenomenon is due to viscosity and surface tension. Modeling with these parameters allowed us to accurately predict the size of hydraulic jumps, regardless of whether the water flows downward or is thrown up.
According to scientists, the results of the study will help develop ways to control the phenomenon, such as adding surfactants to water. Although hydraulic jump is harmless in sinks, powerful waves, turbulence and eddies can occur in water pipes, which lead to rapid wear of utilities and equipment. In addition, controlling the phenomenon will reduce the amount of water used.