Abstract

The onset and nonlinear regimes of the Soret-induced convection in a mixture of dodecane, isobutylbenzene, and tetralin, taken in equal mass fractions and placed in a rectangular porous cavity with rigid impermeable boundaries elongated in the horizontal direction and heated from below, have been numerically investigated. The vertical boundaries of the cavity are thermally insulated. The components of the mixture under consideration are representatives of the main groups of chemical compounds that are oil components. The values of the porosity and permeability of the medium were chosen to be close to the values of real media, such as sand, sandstone, or limestone. The area of such a configuration simulates a hydrocarbon field. Due to the Soret effect (thermal diffusion), the light components of the mixture with positive separation ratios (dodecane and isobutylbenzene) are accumulated in the hot region, whereas the heavy component (tetralin) is accumulated in the cold region. In the case of heating from below (provided by the presence of geothermal gradient under natural conditions), this process may induce convection. It was found that a steady flow occurs in the cavity at a certain value of Rayleigh number; this flow becomes oscillatory with an increase in the Rayleigh number. With a further increase in the Rayleigh number, irregular oscillations arise. Several monotonic and oscillatory regimes, characterized by different spatial scales (from one to ten vortices), were found in the range of Rayleigh numbers under consideration. The oscillations of instantaneous flow characteristics in oscillatory regimes have a complex shape. A steady-state flow regime with an asymmetric structure was found. The ranges of Rayleigh numbers in which the found regimes may exist and the time dependences of the integral characteristics during the formation of steady flows were determined. The effect of supercriticality on the flow structure and concentration distributions of mixture components were analyzed.

中文翻译：

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考虑Soret效应的矩形多孔腔中三元混合物对流的起伏和非线性状态

摘要

十二烷，异丁苯和四氢化萘的混合物中，Soret诱导的对流的开始和非线性状态，以相同的质量分数计，放置在矩形多孔腔中，刚性刚性的渗透边界沿水平方向拉长并从下方加热。进行了数值研究。空腔的垂直边界是隔热的。所考虑的混合物的成分代表了主要成分的化学成分，即油成分。选择介质的孔隙率和渗透率值，使其接近于诸如沙子，砂岩或石灰石之类的真实介质的值。这种配置的区域模拟了一个油气田。由于索雷特效应（热扩散），具有正分离比的混合物的轻组分（十二烷和异丁苯）积聚在高温区域，而重组分（四氢化萘）积聚在寒冷区域。在从下方加热的情况下（由自然条件下存在的地热梯度提供），该过程可能引起对流。结果发现，在一定的瑞利数下，腔体内会产生稳定的流动。随着瑞利数的增加，这种流动变得振荡。随着瑞利数的进一步增加，出现不规则的振荡。在所考虑的瑞利数范围内发现了几种具有不同空间尺度（从一到十个涡旋）的单调和振荡状态。振荡状态下瞬时流动特性的振荡具有复杂的形状。发现具有不对称结构的稳态流态。确定了可能存在所发现状态的瑞利数范围以及在稳定流形成过程中整体特征的时间依赖性。分析了超临界对混合组分流动结构和浓度分布的影响。