摘要
在激波与气泡相互作用中,不同程度的初始扩散可诱导出不同强度的流动不稳定性,然而这种流动不稳定性的来源及其对混合的影响机制仍然不清楚.本研究通过高精度数值模拟方法研究这种流动不稳定性对混合的作用.为了剥离流场中其他因素的影响,提出了一种环量控制方法来保证不同条件流场具有相同的雷诺数Re和佩克莱数Pe.通过考察气泡形态及涡量特征,发现初始扩散越薄,流场后期演化的不稳定性越显著,且这种不稳定性的强度可通过二次斜压环量(Γ_(sbv)/Γ)来度量.进一步使用涡量输运方程考察二次斜压环量的源项演化,发现其增长主要由斜压矩主控.因此,这种由初始扩散诱导的不稳定性可以被定义为二次斜压不稳定性.在混合增长特性方面,对比混合度和标量耗散率的结果表明,具有更强的二次斜压不稳定性所诱导的混合速率也更高.因此这种与雷诺数Re弱相关的二次斜压不稳定性可以促进变密度混合.最后,给出了二次斜压不稳定性强度Γ_(sbv)/Γ与平均混合速率■的平方标度率关系,呈现为:■.
Different strengths of hydrodynamic instability can be induced by the variations in the initial diffusion of shock bubble interaction(SBI),while the influence of hydrodynamic instability on variable-density mixing in SBI remains unclear.The present study aims to investigate the hydrodynamic instability of SBI through high-resolution numerical simulations.To isolate each factor within this instability,a circulation control method is employed to ensure consistent Reynolds number Re and P´eclet number Pe.An examination of the morphology of the bubbles and vorticity dynamics reveals that the hydrodynamic instability can be characterized by secondary baroclinic circulation.Through vorticity budget analysis,the secondary baroclinic circulation is dominated by the baroclinic torque.Therefore,the identified hydrodynamic instability is labeled as secondary baroclinic hydrodynamic instability(SBHI).Regarding mixing characteristics,the investigation on the mixedness and scalar dissipation rate reveals that cases with stronger SBHI exhibit higher mixing rates,indicating SBHI can enhance mixing.Furthermore,the scaling of the time-averaged mixing rate■on the strength of SBHI represented byΓ_(sbv)/Γis revealed:the mixing rate■is increased proportionally to nearly the square ofΓsbv/Γ(■)
作者
韩旭
余彬
刘洪
HAN Xu;YU Bin;LIU Hong(J.C.Wu center for aerodynamics,school of aeronautics and astronautics,shanghai jiao tong university,shanghai 200240,china)
出处
《中国科学：物理学、力学、天文学》
CSCD
北大核心
2024年第10期79-96,共18页
Scientia Sinica Physica,Mechanica & Astronomica
基金
国家资助博士后研究人员计划(编号:GZC20231566)项目。
关键词
激波气泡相互作用
初始扩散
二次斜压不稳定性
变密度混合
shock bubble interaction
initial diffusion
secondary baroclinic hydrodynamic instability
variable-density mixing
