Cavitation and inhomogeneities in underwater acoustics

Cavitation and inhomogeneities in underwater acoustics

Cavitation and inhomogeneities in underwater acoustics Glittingen, FRG, 9-l 1 July 1979 This congress was organized by Professor Werner Lauterborn,...

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Cavitation and inhomogeneities in underwater acoustics Glittingen,

FRG, 9-l

1 July 1979

This congress was organized by Professor Werner Lauterborn, U~liversity of Gijttingen and Professor Leif BjQrn#. Technical University of Denmark. It attracted nearly 60 scientists from countries like Canada. Denmark, France, Germany, Holland. Italy, Japan, Norway, UK, USA, and USSR, and was opened by Mr. EchoId, First Mayor of Ciittingen. The basic idea behind the congress was to bring together scientists working in the fields of cavitation and inhomogeneities, both related to underwater acoustics, to create a fertile atl~~ospllere for exchange of i~lfo~~latio~l and foj discussion of research problems and results of common interest, It was generally felt that the idea of bringing together scientists from these two ~ve~-devel~~~~d and fast growing fields was a good one which led to a successful congress. During the three days of the congress 34 papers wei’c presented. The opening session on sound and bubbles comprised papers by L. van Wijngaarden. Holland. who reviewed the field of sound and shock waves in bubbly liquids and by F.H. Fenlon and I.W. Wonn. USA. who presented some engineering applications of the ampliAcalion ol ~t~odl~lated acoustic waves in gas-liquid mixtures showins the influence of non-linearity, absorption and dispersion. Two sessions were devoted to cavitation bubble dynamics, W, Lauterborn, Germany, gave a survey of the broad variety of activities using coherent optics for the study of cavitation taking piace at the University of ~ttin~en. An interestitlg film showing high-speed photographic investigations of various features of bubble dynamics. in particular the jetting plietlotnena~ was presented. This session also inclu ded a study of acoustic emission from bubbles driven by a sound field, presented by W. Lauterbom’s co-worker, 1:. Cramer. Germany. The effect of viscosity and the develqIIYZII~ of the instability of the spherical shape of a collapsing bubble and a numerical analysis of inviscid bubble collapse was discussed by A. Prosperetti and M. Gibilterra. Italy, and bubble collapse in the vicinity of‘ a two-liquid interface was presented by G.L. Chachine and A. Bovis, France. The second session on cavitation bubble dynamics comprised discussions of free and forced oscillations of spherical gas bubbles (H.I. Roth. Germany), acoustic cavitation and bubble dynamics due to a tension wave (R.A. Wentzell. ~~~Ilii~l~~~ and I~reselita~i~~n of some h~gh-slJee~l l~~)l~)cit~e~l~a. tographic studies of cavitation bubbles (K.I. Ebcling. Germany). Bubble ioilapse studies comprising among other things high-speed photography - 1 million frames per second (Ii. Timm. Germany), bubble cluster collapse (K.A. MQrcir. Denmark~. l~~~logra~l~icgeneration of ~~iulti-b~~l~ble systems (W. Ilcntschell, Germany) and some Russian papers CJII shock wave relaxation and effects and shock wa.vcs in

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bukbl~~ liquids (V. Kretlrinskii. USSR) l;)rllletl 11lc last a~~cl intcrcs~itl~ session of‘ the Ii)-st da!:. A session of bubble spectrometry was opened with a cevicw paper by ti. Medwin. [iSA, trcatinp acoustical bubble spectrometry at sea, showing results of studies at sea of backand material dispersiori at scatter, excess attenuation bubble resonance. This session also included a discussion of’ density distribution of air bubbles below the sea surfaces acoustic mcasuremcIIt of gas (P. Scliippers, tlolland), bubble spectra (A. Ldvik, Norway) mcl bubble si/.e spectruni ~leteriIlina~~~)~i using digital processing of holograms (G. I laussmami, Germany). Based on a modified version of the conical-crevice-in-;r moat model a quantitative model for acoustic zavitatiott inception showing an excellent agreement with experiments was presented by LA. Crum. USA. and some new rcsuits on cavitation threshold proilrctiorr and bubble dynamics given .II the form 01’ non - dimensional graphs were tliscussed by R.E. Apfel. LJSA. J-he section on inhoriiogettcitics in underwater acoustic:, was opened with a survey paper by 1.. [email protected]$. Denmark, who discussed the origin, physical cliaracteris~ics and the acoustic consequences of volutnle inl~oii~ogei~cities. and the acoustic signal distortion in space and time caused by random temperature and velocity ffuct~iatioi~s in the ocean together with the influence of chemical relaxation effects on the absorption of sound was discussed by R.11. Mellen, USA, A clear and illustrative presentation of rccen~ theorctical and experimental developments in the study of acoustic fluctuations in ttic ocean was piven by \‘..I.F. Desaubies. USA. Mesoscale inhomogeneities and turbulence in the ocean and their influence on acoustic wave propagation was presented in a paper by P.D. Scully-Power and WA. vofl Winkle, who also showed wme data for coalescence of inesoscale eddies obtained from manned space platforms. A cmprehensivc study of the influence of stochastic sound speed variatiom on acoustic transmission loss iti shallow water was prescnted by t3.G. Schneider, Germanq, and P.A. (‘rowcher, I;K. gave a thorough exposition of Ilie acoustic scattering l‘rorrl and absorption by wind-wave induced bubble laycts in tllc 100 kt-iz band. Problems in (elation to llotl-tiuc’ar 1 soulld scattering by sInal bLlblllcs (I’.M. Tih1l:litJl. (;c‘ril~aii!~I and freclucncy conversion effects ii1 @s-liquid rIri\turcs (Y.A. Kobelcv. I../\. Ostrovslq and ;\.hl. Satin. I LSSR) rounded off the last session of the congress. The great nuruber of papers ol a high ifltci uatiomj Ievci prescntcd may be expected to rnahc valuable to scicirtists iii unrlcrwater acoustics the proccedirtgs of this ~~tml‘ertilcc. which will be published by Spriqcr Vt%rlagshortI)