粘弹性流体内弹性边界附近空化气泡动力学特性研究

Cavitation bubble dynamics have been proved to play a key role in a variety of novel medical diagnostic and therapeutic technologies utilizing ultrasound and lasers. However, all the relevant researches concentrated on the cavitation bubbles near the elastic boundaries in Newtonian fluids, whose behaviors are definitely different from the ones in the actual situation due to the non-Newtonian properties of biological fluids. Therefore, an innovative idea using viscoelastic fluids to mimic biological fluids is proposed presently, so that the dynamic behaviors of cavitation bubble in related medical technologies could be reproduced. This project is mainly to study the characteristics of cavitation bubble dynamics near the elastic boundaries in the viscoelastic fluids. Specifically, the research contents include three aspects: (1) Systematic experimental study on the behaviors of cavitation bubble near the elastic boundaries in the viscoelastic fluids and its interaction with the elastic boundaries; (2) Establishment of numerical simulation technique for the cavitation bubble dynamics near the elastic boundaries in the viscoelastic fluids by combining lattice Boltzmann method with immersed boundary method; (3) Investigating the effect of viscoelasticity on the cavitation bubble dynamics near the elastic boundaries and the corresponding mechanisms based on the results of experiments and numerical simulations. The research achievements are bound to establish theoretical foundation and provide important guidance for the utilization and control of cavitation bubble dynamics in actual medical diagnostic and therapeutic technologies, and thus of great values to the academic and medical applications.

空化气泡动力学效应已被证实在应用超声和激光的各种新型医学诊断和治疗技术中发挥着关键作用，但目前相关研究均针对牛顿流体弹性边界附近空化气泡，而生物流体的非牛顿特性势必使上述研究结果偏离实际情况。因此，本项目提出采用粘弹性流体模拟生物流体以再现相关医学技术中空化气泡动力学行为的创新性思想，主要研究粘弹性流体内弹性边界附近空化气泡动力学特性。具体研究内容包括三个方面：（1）系统地实验研究粘弹性流体内弹性边界附近空化泡动力学行为及其与弹性边界的相互作用，以及不同参数的影响规律；（2）结合格子Boltzmann方法和浸入边界法建立粘弹性流体弹性边界附近空化气泡动力学数值模拟技术；（3）基于实验和数值模拟结果探究粘弹性效应对弹性边界附近空化气泡动力学特性的影响机理。本项目研究结果将为空化气泡动力学效应在实际医学诊断和治疗技术中的利用和控制奠定理论基础，并提供重要指导，因而具有重要的学术和医学应用价值。

空化泡动力学效应已被证实在应用超声和激光的各种新型医学诊断和治疗技术中发挥着关键作用，但目前相关研究均针对牛顿流体弹性边界附近空化泡，而生物流体的非牛顿流体特性对相应尺寸的空化泡动力学特性的影响尚不清晰。因此，本项目提出了采用粘弹性流体模拟生物流体以再现相关医学技术中空化泡动力学行为的创新性思想，主要研究了粘弹性流体内弹性边界附近空化气泡动力学特性。具体研究内容包括三个方面：（1）开展了粘弹性流体内近弹性边界空化泡动力学行为可视化实验研究，建立了考虑不同弹性模量、空化泡与边界之间无量纲距离、非牛顿流体特性的空化泡动力学实验数据库，分析了边界弹性和流体粘弹性对空化泡动力学行为的影响规律；（2）建立了稳定计算的空化泡动力学数值模拟方法，开展了水中和剪切稀变流体内不同界面附近空化泡动力学数值模拟研究，获得了描述剪切稀变流体剪切粘度随剪切率变化的Carreau模型中各参数对空化泡动力学的影响规律，确定了起主要影响作用的模型参数，实现了粘弹性流体内空化泡动力学的数值模拟；（3）基于可视化实验和数值模拟结果，通过分析空化泡形态演变、弹性边界变形、射流行为、空化泡迁移运动、压力分布等，探究了非牛顿流体特性、界面性质、空化泡与边界之间距离对空化泡动力学行为的影响机理。本项目研究结果为空化气泡动力学效应在实际医学诊断和治疗技术中的利用和控制奠定理论基础，并提供重要指导，因而具有重要的学术和医学应用价值。