On November 17 and 18, 2005 the workshop "Cavitation: Description, quantification and standardization for practical applications" was realized under the - surely somewhat provoking - motto "Everybody uses cavitation, but nobody really understands it". On two days, 40 participants (see photo) from universities, research institutes and manufacturers throughout Germany intensively discussed the fundamentals and applications of this complicated and complex process.

The first part dealt with the progress of the theoretical and fundamental description of single cavitation bubbles and clouds. In particular the extreme physical conditions which may prevail in or around a bubble can better and better be described. However, multiple coupling of the bubbles among one another, which also causes chaotic behaviour, still makes a lot of difficulties.

A main objective of the workshop - which is also a special objective of PTB - was the improvement of the quantitative investigation of cavitation and its application. The possibilities at present available of determining suitable parameters by objective measurements which may lead to an assessment of the cavitation field were shown. Such quantitative parameters are urgently required for better understanding and optimization of the application processes. It became apparent that good progress has already been achieved in sound field measurements and that theoretical sound field models are available. A linkage to real application must, however, still be elaborated.

On the second day, work was concentrated on concrete applications, and a wide field of subjects from waste water treatment to medical contrast media was examined. This interdisciplinary approach resulted in many interesting discussions which then led to the final panel discussion. At the end, the conclusion of the participants was clear: A profitable event which should be repeated in two years. Maybe then we will understand cavitation a little better.