Fluxes across double-diffusive interfaces: a one-dimensional-turbulence study
Fluxes across double-diffusive interfaces: a one-dimensional-turbulence study
复制标题
跨双扩散界面的通量：一维湍流研究
DOI：
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发表时间：
2010
影响因子：
3.7
通讯作者：
D. Lignell
中科院分区：
文献类型：
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作者：
E. Gonzalez;A. Kerstein;D. Lignell
本文采用一维湍流(ODT)数值模拟方法，对非剪切和剪切双扩散界面上的热量和盐通量进行了参数研究。这是因为需要了解这些通量如何随与流体分子性质和背景剪切有关的参数而变化。从头到尾都与以前的模型和可用的测量结果进行了比较。在非剪切界面，无因次热流密度Nu与稳定性参数Rρ、瑞利数Ra和普朗特数Pr成正比，Pr在3~100时为Nu~(Ra/Rρ)0.37±0.03，Pr在0.01~1时为Nu~(Ra/Rρ)0.31Pr0.22±0.04。这里Ra/Rρ可视为失稳和稳定化效果的比值。模拟结果还表明，当Rρ足够大时，盐热流比Rf与Pr无关，随刘易斯数Le变化为Rf~Le0.4 1±0.0 4；当界面受到严重侵蚀时，当Rρ较低时，则偏离这个表达式。在剪切界面上，模拟结果显示了三种流型。当Richardson数Ri≪1，剪切诱导混合占优势时，热流密度随界面上的水平速度差和Rf=Rρ而变化。在Ri~1附近，热通量和盐通量随着切变的增加而急剧增加。当Ri≫为1时，熔剂的流动结构和标度与未剪切界面相似。
This work is a parametric study of the fluxes of heat and salt across unsheared and sheared double-diffusive interfaces using one-dimensional-turbulence (ODT) simulations. It is motivated by the need to understand how these fluxes scale with parameters related to the fluid molecular properties and background shear. Comparisons are made throughout with previous models and available measurements. In unsheared interfaces, ODT simulations show that the dimensionless heat flux Nu scales with the stability parameter Rρ, Rayleigh number Ra and Prandtl number Pr as Nu ~ (Ra/Rρ)0.37±0.03 when Pr varies from 3 to 100 and as Nu ~ (Ra/Rρ)0.31Pr0.22±0.04 when Pr varies from 0.01 to 1. Here Ra/Rρ can be seen as the ratio of destabilizing and stabilizing effects. The simulation results also indicate that the ratio of salt and heat fluxes Rf is independent of Pr, scales with the Lewis number Le as Rf ~ Le0.41±0.04 when Rρ is large enough and deviates from this expression for low values of Rρ, when the interface becomes heavily eroded. In sheared interfaces, the simulations show three flow regimes. When the Richardson number Ri ≪ 1, shear-induced mixing dominates, the heat flux scales with the horizontal velocity difference across the interface and Rf = Rρ. Near Ri ~ 1 the heat and salt fluxes are seen to increase abruptly as the shear increases. The flow structure and scaling of the fluxes are similar to those of unsheared interfaces when Ri ≫ 1.