The paper is devoted to numerical simulation of nonlinear regimes of a binary liquid mixture in rectangular cavities elongated in the horizontal direction. The boundaries of the cavity are considered to be rigid, impermeable to the substance. The vertical boundaries are thermally insulated; constant different temperatures corresponding to heating from below are maintained on the horizontal boundaries. The calculations are carried out in the framework of a non-stationary approach, using the Boussinesq approximation. An aqueous NaCl solution was chosen as the studied mixture. The calculations were carried out for cases of Earth and reduced gravity. The local and integral characteristics of nonlinear regimes are obtained, the structure of the arising flow and the concentration distribution are found. An analysis of the data shows that in the case of terrestrial gravity in a square cavity, the regime of stationary oscillations with the reconnection of vortices is realized. A multi-vortex flow occurs and its intensity oscillates in an irregular manner in a rectangular cavity under Earth gravity. A stationary flow is observed when gravity is reduced: a single-vortex and a multi-vortex occur for a square and a rectangular cavity, respectively. When an intensity of convective flow is low, a process of mixture separation close to purely diffusive is observed at the initial stage of convection development. It was found that a sharp increase in the intensity of motion at the initial stage of convection development affects the separation of the mixture, it becomes much stronger. The resulting flow mixes the mixture quite strongly: it remains homogeneous in the central part of the cavity, strong changes in concentration are observed near the boundaries. In the case of Earth gravity, the concentration gradients near the upper and lower boundaries are not equal; in the case of reduced gravity, they are the equal.

本文致力于数值模拟矩形腔中水平方向上拉长的二元液体混合物的非线性状态。腔的边界被认为是刚性的，物质不能渗透。垂直边界是隔热的。在水平边界上保持与从下方加热相对应的恒定的不同温度。使用Boussinesq逼近在非平稳方法的框架内进行计算。选择NaCl水溶液作为研究混合物。计算是针对地球和重力降低的情况。得到了非线性状态的局部和积分特性，得到了上升流的结构和浓度分布。数据分析表明，在方腔中的地心引力的情况下，实现了随着涡旋的重新连接而产生的平稳振荡状态。在地球重力作用下，在矩形腔中会发生多涡流，并且其强度会以不规则的方式振荡。当重力降低时，观察到平稳流动：正方形和矩形空腔分别发生单涡旋和多涡旋。当对流流动强度低时，在对流发展的初始阶段观察到接近纯扩散的混合物分离过程。已经发现，在对流发展的初始阶段，运动强度的急剧增加会影响混合物的分离，并变得更强。产生的流将混合物强烈混合：它在空腔的中心部分保持均匀，在边界附近观察到浓度的强烈变化。在地球重力的情况下，上下边界附近的浓度梯度不相等。在重力降低的情况下，它们是相等的。