Silencing corrugated pipes: Whistling mitigation by liquid addition to vertical corrugated pipe flow

Flow-induced acoustics are a well-known phenomenon, occurring in a broad variety of applications, as well as in nature. In many applications, the produced acoustics are purposeful, e.g. for communication and in musical instruments. In other circumstances, however, the sound and vibrations are a nuisance, and even harmful to human beings and the environment. Pipes with internally grooved or corrugated walls can be such a source of sound production. These pipes find broad application due to the local stiffness that is combined with larger scale flexibility of the pipes. The main industrial use of corrugated pipes is as flexible connections, transporting a gas or liquid between e.g. ships and onshore storage facilities, or between subsea bore-wells and floating production facilities.