2018/12/14 by Scott A. Wieland, Peter E. Hamlington, Wieland, Scott A. +5
Engineering · Environmental Science · #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Turbulent Flows #Particle Dynamics in Fluid Flows #Wind and Air Flow Studies
paper · pdf · doi:10.48550/arxiv.1812.05987
openalex publication_date 2018/12/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The effects of isothermal stratification strength on vorticity dynamics for\nsingle-mode Rayleigh-Taylor instability (RTI) are examined using two\ndimensional fully compressible wavelet-based direct numerical simulations. The\nsimulations model low Atwood number (A=0.04) RTI development for four\ndifferent stratification strengths, corresponding to Mach numbers from 0.3\n(weakly stratified) to 1.2 (strongly stratified), and for three different\nperturbation Reynolds numbers, from 5,000 to 20,000. All simulations use\nadaptive wavelet-based mesh refinement to achieve very fine spatial resolutions\nat relatively low computational cost. For all stratifications, the bubble and\nspike go through the exponential growth regime, followed by a slowing of the\nRTI evolution. For the weakest stratification, this slow-down is then followed\nby a re-acceleration, while for stronger stratifications the suppression of RTI\ngrowth continues. Bubble and spike asymmetries are observed for weak\nstratifications, with bubble and spike growth rates becoming increasingly\nsimilar as the stratification strength increases. For the range of cases\nstudied, there is relatively little effect of Reynolds number on bubble and\nspike heights, although the formation of secondary vortices becomes more\npronounced as Reynolds number increases. The underlying dynamics are analyzed\nin detail through an examination of the vorticity transport equation, revealing\nthat incompressible baroclinicity drives RTI growth for small and moderate\nstratifications, but increasingly leads to the suppression of vorticity\nproduction and RTI growth for stronger stratifications. These variations in\nbaroclinicity are used to explain the suppression of RTI growth for strong\nstratifications, as well as the anomalous asymmetry in bubble and spike growth\nrates for weak stratifications.\n