Title: Spatio-temporal pulse propagation during highly-resolved onset of Rayleigh-Taylor and Kelvin-Helmholtz Rayleigh-Taylor instabilities Show Chinese title

Title: 拉格朗日-泰勒和开尔文-亥姆霍兹拉格朗日-泰勒不稳定性高度解析起始阶段的空间脉冲传播

Abstract: The present study explores the onset of the Rayleigh-Taylor instability (RTI) and Kelvin-Helmholtz Rayleigh-Taylor instability (KHRTI) with highly-resolved direct numerical simulations of two setups which consider air at different temperatures (or densities) and/or velocities in two halves of three-dimensional cuboidal domains. The compressible Navier-Stokes equations are solved using a novel parallel algorithm which does not involve overlapping points at sub-domain boundaries. The pressure disturbance field is compared during onset of RTI and KHRTI and corresponding convection- and advection-dominated mechanisms are highlighted by instantaneous features, spectra, and proper orthogonal decomposition. The relative contributions of pressure, kinetic energy and rotational energy to the overall energy budget is explored for both instabilities, revealing acoustic trigger to be the incipient mechanism for both RTI and KHRTI. The nonlinear, spatio-temporal nature of the instability is further explored by application of a transport equation for enstrophy of compressible flows. This provides insights into the similarities and differences between the onset mechanisms of RTI and KHRTI, serving as a benchmark data set for shear and buoyancy-driven instabilities across diverse applications in geophysics, nuclear energy and atmospheric fluid dynamics. Show Chinese abstract

Abstract: 本研究通过高分辨率的直接数值模拟，探讨了Rayleigh-Taylor不稳定性和Kelvin-Helmholtz Rayleigh-Taylor不稳定性（KHRTI）的起始条件。所研究的两个设置考虑了三维立方体域内两半部分具有不同温度（或密度）和/或速度的空气。 使用一种新颖的并行算法求解可压缩Navier-Stokes方程，该算法在子域边界上不涉及重叠点。 在RTI和KHRTI起始过程中比较了压力扰动场，并通过瞬时特征、频谱和正交分解突出对应的对流和平流主导机制。 对于这两种不稳定性，探索了压力、动能和旋转能量对整体能量预算的相对贡献，揭示声学触发作为RTI和KHRTI的初始机制。 通过可压缩流动涡量输运方程的应用，进一步探索了不稳定的非线性时空特性。 这提供了关于RTI和KHRTI起始机制之间相似性和差异性的见解，为地球物理、核能和大气流体力学中的剪切和浮力驱动不稳定性提供了基准数据集。