Finite amplitude doubly diffusive convection
Finite amplitude doubly diffusive convection
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有限振幅双扩散对流
DOI：
10.1017/s0022112072002915
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发表时间：
1972
影响因子：
3.7
通讯作者：
J. Straus
中科院分区：
文献类型：
--
作者：
J. Straus
含有温度和盐度梯度的一层流体受到几种地球物理不稳定性的影响。当盐度和温度向上升高时，即使密度剖面显示稳定，地层也可能变得不稳定。这种“双重扩散”的不稳定性，首先由斯特恩处理，在实验中被认为是由向上和向下流动的细手指组成的。线性分析不能解释这种小的水平尺度的稳态过程，但对问题的非线性处理结合稳定性分析表明，只有小尺度的运动是稳定的，当盐度梯度大于开始不稳定所必需的。在小盐扩散率的极限下，用伽辽金技术计算了盐的通量，发现在随盐度和温度梯度增加而减小的波长处达到最大值。讨论了有限振幅解的稳定性；发现只有小尺度运动是稳定的，并且发现最稳定模式的波长与最大盐通量的波长比较有利。
A layer of fluid containing gradients of both temperature and salinity is subject to several instabilities of geophysical interest. When the salinity and temperature increase upwards, the layer may become unstable even if the density profile indicates stability. This ‘doubly diffusive’ instability, first treated by Stern, is seen experimentally to consist of thin fingers of up- and downgoing fluid. Linear analysis cannot explain this small horizontal scale for a steady-state process, but a nonlinear treatment of the problem combined with a stability analysis indicates that only small-scale motions are stable when the salinity gradient is larger than that necessary for the onset of instability. In the limit of small salt diffusivity the flux of salt is calculated using the Galerkin technique and found to reach a maximum at a wavelength that decreases with increasing salinity and temperature gradients. The stability of the finite amplitude solutions is treated; only small-scale motions are found to be stable and the wavelength of the most stable mode is found to compare favourably with the wavelength that maximizes the salt flux.