Liquid bubble

A bubble is a gaseous body within a liquid. It is separated from the latter by a self- phase interface. There are bubble and liquid in peace with one another, the bubble is spherical. Moving the bladder, for example, under the influence of gravity to the liquid, flattens the bubble at the side lying in the direction of increasing speed from. In the spherical case ( interfacial tension actually ) ( the liquid / gas interface actually ) and the radius r can the bubble internal pressure of the ambient pressure, the surface tension of the liquid charge:

Small bubbles therefore have a high internal pressure. The complement to the bladder is the drop.

Corrosion caused by bubbles

In flowing, turbulent or boiling liquids vapor bubbles of the respective liquid can form where the vapor pressure exceeds the ambient pressure and the need to overcome the surface tension is still able. Device, the bubble thus formed in a region with a different thermodynamic state where these conditions are no longer met, the bladder drops below the condensation of the vapor under the influence of ambient pressure and upper (border) surface tension together. The inertia of the collapsing fluid can at the point where the center of the bubble was created a region of very high pressure, which propagates as a shock wave. When the bladder is only a tiny bit flattened and slightly asymmetrical created by the collapsing of a cumulative jet, in which dynamic pressures arise, which can destroy any material.

This process is called cavitation including playing in the design of hydraulic equipment, pipe fittings, such as pumps or valves and ship propellers an important role.