Dynamics of cavitation bubbles in compressible two-phase fluid flow

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The primary objective of the project is to provide a better understanding of the damaging mechanism caused by the collapse of a single cavitation bubble near to a compliant wall. For this purpose, the equations for compressible two-phase flows (35) will be coupled with a system of partial differential equations modeling elastic-plastic behavior of the solid. In order to model phase transition effects and to take into account tiny bubbles forming during the bubble collapse that can not be resolved, the existing flow solver will be extended by a homogeneous description for two-phase mixtures. The experience of the French partners concerning homogenized models such as (40) will be used for the selection as well as for the implementation of such an ansatz.In the experimental part two problems will be considered; (i) pressure effects on bubble dynamics, and (ii) fluid-structure interaction. In part (i), bubbles in a heated liquid and bubbles driven by a sound field will be investigated by established methods. Also, laserinduced fluorescence shall be employed to visualize temperature variations in the liquid. In part (ii) a novel method to measure the time-dependent pressure load on the wall based on interferometry with short laser pulses shall be developed and furthermore extended to visualize stress states in a transparent solid as the boundary. It will be combined with the established experimental methods to obtain comprehensive experimental data on the bubble collapse near a wall.The experimental results will be used as a data base for comparison with numerical calculations.