Dynamics of cavitation bubbles in compressible two-phase fluid flow

该项目的主要目的是提供一个更好的理解所造成的破坏机制的一个单一的空泡崩溃附近的一个顺应性的墙壁。为此目的，可压缩两相流的方程（35）将与模拟固体的弹塑性行为的偏微分方程系统耦合。为了模拟相变的影响，并考虑到微小的气泡形成的气泡崩溃，不能解决，现有的流动求解器将扩展的两相混合物的均匀描述。法国合作伙伴关于均匀化模型（如（40））的经验将用于选择和实施这样一个模型。在实验部分将考虑两个问题：（i）压力对气泡动力学的影响，和（ii）流体-结构相互作用。在部分（i）中，将通过已建立的方法研究加热液体中的气泡和由声场驱动的气泡。此外，应采用激光诱导荧光来观察液体中的温度变化。在第（ii）部分中，应开发一种基于短激光脉冲干涉测量法测量壁上随时间变化的压力载荷的新方法，并进一步扩展到可视化透明固体中的应力状态作为边界。结合已有的实验方法，获得了近壁空泡溃灭的全面实验数据，并将实验结果作为与数值计算比较的数据基础。

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.