Characterization of Surfaces and the Estimation of Shock Induced Vorticity

Jameson, L ; Ray, J ; Peyser, T

Lawrence Livermore National Laboratory

关键词: Fourier Analysis;    Roughness;    Instability;    99 General And Miscellaneous//Mathematics, Computing, And Information Science;   

DOI  :  10.2172/15002789
RP-ID  :  UCRL-ID-150039
RP-ID  :  W-7405-ENG-48
RP-ID  :  15002789

美国|英语

来源: UNT Digital Library

【 摘 要 】

When shocks impinge on a surface separating fluids of two different densities, one observes the development and growth of various vortical structures. The flow induced by this Richtmyer-Meshkov (RM) instability depends on a variety of factors such as the shock strength, the density ratio of the fluids and the exact form of the surface perturbation. The most common way to model the form of the surface perturbation is through Fourier analysis which is suitable for large-scale sinusoidal structures and is straightforward mathematically. In surfaces of practical interest, however, to a wide range of application, there may also be a broad spectrum of high frequency modes in addition to the lower frequency modes described by Fourier methods. We propose here that these high frequency modes can be efficiently quantified in terms of wavelet analysis. From a numerical point of view, the scale that the roughness occurs at is far to small to numerically resolve and thus we propose that our new methodology can be used to model the subgrid scale generation of vorticity. Thus the combination of wavelet analysis and Fourier analysis will be used to model the generation of vorticity for the RM instability.