Oscillations, Waves, and Interactions - GWDG

10 M. R. Schroeder, D. Guicking and U. Kaatze
Drittes Physikalisches Institut at the turn of the millenium.
airborne sound was constructed for its potential to attenuate the rolling noise of
tyres, covering the relevant frequency range from 700 Hz through 1300 Hz [81].
Some basic research was done on the question “How does the sound get out of a
ship into the water”. Experiments and analytical models of sound radiation from flat
plates [82] were followed by investigations with thick-walled cylindrical shells. The
calculation of their resonance frequencies (at which the sound radiation is maximum)
is all but trivial – the rigorous theory demands for the solution of partial differential
equations of 10th order [83]. Attempts to find simpler calculations resulted in a
surprisingly good approximation [84], reducing the computational effort to solving a
third-order algebraic equation. Comparison with experimental data revealed errors
of a few percent only. As an aside, the critical frequency of flat plates turned out to
be strongly dependent on the density of the surrounding medium [85].
The activities on underwater sound research, except for cavitation, ended with the
retirement of Dieter Guicking who has supervised much of the work summarised here
since about 1970.
7 Cavitation
From the very beginning cavitation was among the areas of research of the Dritte
Physikalische Institut. In fact, already in Berlin Meyer and Tamm had been concerned
with vibrations of bubbles in liquids [86]. Methods to study cavitation phe-