• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文OA文献 >Buoyancy-driven instabilities of miscible two-layer stratifications in porous media and Hele-Shaw cells
【2h】

Buoyancy-driven instabilities of miscible two-layer stratifications in porous media and Hele-Shaw cells

机译：多孔介质和Hele-Shaw细胞中可混溶两层分层的浮力驱动不稳定性

代理获取
本网站仅为用户提供外文OA文献查询和代理获取服务，本网站没有原文。下单后我们将采用程序或人工为您竭诚获取高质量的原文，但由于OA文献来源多样且变更频繁，仍可能出现获取不到、文献不完整或与标题不符等情况，如果获取不到我们将提供退款服务。请知悉。
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Buoyancy-driven instabilities of a horizontal interface between two miscible solutions in the gravity field are theoretically studied in porous media and Hele-Shaw cells (two glass plates separated by a thin gap). Beyond the classical Rayleigh-Taylor (RT) and double diffusive (DD) instabilities that can affect such two-layer stratifications right at the initial time of contact, diffusive-layer convection (DLC) as well as delayed-double diffusive (DDD) instabilities can set in at a later time when differential diffusion effects act upon the evolving density profile starting from an initial step-function profile between the two miscible solutions. The conditions for these instabilities to occur can therefore be obtained only by considering time evolving base-state profiles. To do so, we perform a linear stability analysis based on a quasi-steady-state approximation (QSSA) as well as nonlinear simulations of a diffusion-convection model to classify and analyse all possible buoyancy-driven instabilities of a stratification of a solution of a given solute A on top of another miscible solution of a species B. Our theoretical model couples Darcy's law to evolution equations for the concentration of species A and B ruling the density of the miscible solutions. The parameters of the problem are a buoyancy ratio R quantifying the ratio of the relative contribution of B and A to the density as well as δ, the ratio of diffusion coefficients of these two species. We classify the region of RT, DD, DDD and DLC instabilities in the (R, δ) plane as a function of the elapsed time and show that, asymptotically, the unstable domain is much larger than the one captured on the basis of linear base-state profiles which can only obtain stability thresholds for the RT and DD instabilities. In addition the QSSA allows one to determine the critical time at which an initially stable stratification of A above B can become unstable with regard to a DDD or DLC mechanism when starting from initial step function profiles. Nonlinear dynamics are also analysed by a numerical integration of the full nonlinear model in order to understand the influence of R and δ on the dynamics. © 2011 Cambridge University Press.
机译：从理论上研究了多孔介质和Hele-Shaw池（两个玻璃板之间由细缝隔开）在重力场中两个可混溶溶液之间水平界面的浮力驱动不稳定性。除了经典的Rayleigh-Taylor（RT）和双扩散（DD）不稳定性之外，它们可能在接触初期就影响这种两层分层，扩散层对流（DLC）以及延迟双扩散（DDD）不稳定性当微分扩散效应从两个可混溶溶液之间的初始阶跃函数轮廓开始，随着密度扩散作用作用于不断变化的密度轮廓时，可以在随后的某个时间开始计算。因此，仅通过考虑随时间演变的基态曲线，才能获得发生这些不稳定性的条件。为此，我们基于准稳态近似（QSSA）以及扩散对流模型的非线性模拟执行线性稳定性分析，以对所有可能的由浮力驱动的不稳定性分层进行分类和分析。一个给定的溶质A在一个物种B的另一个可混溶溶液之上。我们的理论模型将达西定律与用于确定物种A和B的浓度的演化方程相结合，从而决定了该可混溶溶液的密度。问题的参数是一个浮力比R，它量化B和A对密度的相对贡献比以及δ（这两种物质的扩散系数之比）。我们将（R，δ）平面中RT，DD，DDD和DLC不稳定性的区域根据经过的时间进行分类，并表明，渐近地，不稳定域远大于基于线性基准捕获的域状态配置文件，只能获取RT和DD不稳定性的稳定性阈值。另外，QSSA允许确定从初始阶跃函数轮廓开始时，对于DDD或DLC机制而言，高于B的A最初稳定的分层可能变得不稳定的临界时间。为了了解R和δ对动力学的影响，还通过对整个非线性模型进行数值积分来分析非线性动力学。 ©2011剑桥大学出版社。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
代理获取

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号