## The Euler number—Technological challenges of cavitation

*Peter Monkewitz*^{*}, Flavio Noca and Etienne
Robert, Laboratory of Fluid Mechanics, Swiss Federal Institute
of Technology, Lausanne

^{*} This Invited Lecture will be presented
by Peter Monkewitz

The Euler number is essentially the ratio of the typical static
pressure minus the vapor pressure and the typical dynamic pressure in
a given flow. It therefore characterizes the propensity of the flow to
cavitate, i.e. to form vapor bubbles. The technological importance of
the phenomenon is shown on two examples—The abrasion of a solid
by micron size particles (as for instance in a “wire saw”)
and the dynamics of laser generated cavitation bubbles in a liquid
jet.