Figure 15. Cloud returning to original shape and size.

key problems and laboratory investigations. Here we have described a progression of computational investigations which began with the calculations by Wang and Brennen (40,41,42) of the behaviour of a spherical cloud of bubbles subjected to a low pressure episode. Wang and Brennen (50) then extended this one-dimensional methodology to investigate the steady flow of a bubbly, cavitating mixture through a convergent/divergent nozzle. Under certain parametric conditions, the results are seen to model the dynamics of flashing within the nozzle. Moreover, it is clear from these steady flow studies that there are certain conditions in which no steady state solution exists and it is speculated that the flow under those conditions may be inherently unstable. Of course, it has frequently been experimentally observed that cavitating nozzle flows can become unstable and oscillate violently. Finally, we have also described recent efforts (Colonius et al. (46)) to extend the code to two and three space dimensions.

In conclusion, these recent investigations provide new insights into the dynamics and acoustics both of individual cavitation bubbles and of clouds of bubbles. In turn, these insights suggest new ways of modifying and possibly ameliorating cavitation noise and damage.

10. Acknowledgements

Our profound thanks to the Office of Naval Research for the support which it provided under contract N00014–97–1–0002 and to the technical monitor Edwin Rood who sponsored much of the research described herein.

REFERENCES

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