DNS results (Nusselt number) for: The effect of rotation on double diffusive convection: Perspectives from linear stability analysis

Diffusive convection can occur when two constituents of a stratified fluid have opposing effects on its stratification and different molecular diffusivities. This form of convection arises for the particular temperature and salinity stratification in the Arctic Ocean and is relevant to heat fluxes. Previous studies have suggested that planetary rotation may influence diffusive-convective heat fluxes, although the precise physical mechanisms and regime of rotational influence are not well understood. A linear stability analysis of a temperature and salinity interface bounded by two mixed layers is performed here to understand the stability properties of a diffusive-convective system, and in particular the transition from non-rotating to rotationally-controlled heat transfer. Rotation is shown to stabilize diffusive convection by increasing the critical Rayleigh number to initiate instability. In the rotationally-controlled regime, a -4/3 power law is found between the critical Rayleigh n...

扩散对流（diffusive convection）可发生于层化流体（stratified fluid）的两种组分对其层化作用相反且分子扩散率（molecular diffusivities）存在差异的情形下。该类对流形式在北冰洋的特定温度-盐度层化条件下出现，并与热通量（heat fluxes）密切相关。既往研究表明，行星自转（planetary rotation）可能会影响扩散对流热通量，但目前学界对自转影响的具体物理机制及作用区间尚未形成清晰认知。本文针对由两层混合层界定的温盐界面开展线性稳定性分析（linear stability analysis），以探究扩散对流系统的稳定性特征，尤其是从非旋转热传递到旋转控制热传递的转变规律。研究发现，行星自转通过提升引发失稳的临界瑞利数（Rayleigh number），可对扩散对流起到稳定作用。在旋转控制区间内，临界瑞利数与……间满足-4/3次幂律（power law）关系。