Acoustic Streaming

​​Streaming is a term to describe a steady time-averaged mass-flux density or velocity induced by oscillating acoustic waves in a fluid. Large amplitude sound propagation in a fluid may result in a steady motion of the fluid. This nonlinear phenomenon is known as acoustic streaming.

This acoustic streaming can be induced by ultrasonic flexural vibrations and may be effective in enhancement of convective heat transfer, ultrasonic cleaning of contaminated surfaces, localized micro-mixing and etc.

Once USP runs, acoustic vibration is transferred to whole tube surface in heat exchanger through transducers welded on tube sheet. Then whole tube surface turn into a wide acoustic radiation surface having radiation force and the acoustic radiation force makes acoustic streaming into the fluid which flows in whole tubes. As this acoustic streaming acts vertically against flow direction of fluid (laminar flow), particles motion in the fluid becomes significantly active and then convection and turbulent flow are generated in the flow in tube. These two key kinetic energies given continuously by USP, acoustic vibration on the tube surface and acoustic streaming in the fluid, can prevent or mitigate fouling deposit on tube surface and fouling forming in the fluid and also can dissolve a preformed fouling.