EXPERIMENTAL INVESTIGATION OF THERMAL CONVECTION IN MIXTURES UNDER CONDITIONS OF THE GRAVITATION SEPARATION

The thermal convection of liquid binary mixtures and magnetic colloids under conditions, when there is a concentration gradient in a liquid at the same time with a temperature gradient and the mechanism of the support of this gradient exists due to the gravitation sedimentation of brown magnetic particles, their units or macroscopic heterogeneities of concentration, has been investigated in the paper. Temperature dields have been measured. The concentration distribution in magnetic liquids has been investigated. Speeds of convection flows have been measured. The theoretical analysis has been held. The influence of gravitation gradients of concentration on convection flows under conditions of the side and lower heating has been detected and investigated for the first time. The oscillatory instability and oscillatory regimes of convection near the crisis of the stable equilibrium have been investigatedAvailable from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

On thermodiffusion influence on the dopant distribution during the freezing of binary liquid column

The relevance of the study is caused by the necessity of the extension of fundamental experimental and theoretical research in the field of macroscopic hydrodynamic phenomena in multicomponent liquid molecular mixtures. The results can be used in chemical technologies; they can change our point of view on the processes of deep waste water reclamation and safe utilization of geological resources. The main aim is to investigate the phenomenon of liquid molecular mixtures separation in thin channels by means of thermodiffusion over the self-cooling procedure; to compare different mechanisms of transfer - convection of short duration, diffusion and thermodiffusion - on the process of the components redistribution in the thin columns filled with a water-salt solution. The undertaken investigation has been executed to explain the origination of appreciable vertical stratification of different components of the mixture that gives significant variability of water salinity along the channel height. The methods used in the study: to fulfill the plan of our research the experimental and theoretical methods had been used that simulated physical processes under consideration: experimental data on concentration measurement which were taken during the freezing of the samples had been compared with the results of direct numerical modeling received by the finite difference method. The measurement of temperature fields was realized with the help of thermocouple technique. Numerical procedure was based on the full equations system of thermohaline convection. The results. The authors have shown that thermal convection, diffusion and strong positive thermodiffusion typical for the water-salt solutions can lead to the evident longitudinal division on components in the thin vertical channels filled with liquid mixtures over the selfcooling process and following freezing. The explanation of the strong longitudinal division in the liquid mixtures is based on the joint effect of two different physical mechanisms. There are thermodiffusion displacement of the admixture to the boundary layers of the channel and the large-scale axial convective flow. The similar phenomena could take place in artificial hydrological systems, natural geological processes and technological applications

On thermodiffusion influence on the dopant distribution during the freezing of binary liquid column

The relevance of the study is caused by the necessity of the extension of fundamental experimental and theoretical research in the field of macroscopic hydrodynamic phenomena in multicomponent liquid molecular mixtures. The results can be used in chemical technologies; they can change our point of view on the processes of deep waste water reclamation and safe utilization of geological resources. The main aim is to investigate the phenomenon of liquid molecular mixtures separation in thin channels by means of thermodiffusion over the self-cooling procedure; to compare different mechanisms of transfer - convection of short duration, diffusion and thermodiffusion - on the process of the components redistribution in the thin columns filled with a water-salt solution. The undertaken investigation has been executed to explain the origination of appreciable vertical stratification of different components of the mixture that gives significant variability of water salinity along the channel height. The methods used in the study: to fulfill the plan of our research the experimental and theoretical methods had been used that simulated physical processes under consideration: experimental data on concentration measurement which were taken during the freezing of the samples had been compared with the results of direct numerical modeling received by the finite difference method. The measurement of temperature fields was realized with the help of thermocouple technique. Numerical procedure was based on the full equations system of thermohaline convection. The results. The authors have shown that thermal convection, diffusion and strong positive thermodiffusion typical for the water-salt solutions can lead to the evident longitudinal division on components in the thin vertical channels filled with liquid mixtures over the selfcooling process and following freezing. The explanation of the strong longitudinal division in the liquid mixtures is based on the joint effect of two different physical mechanisms. There are thermodiffusion displacement of the admixture to the boundary layers of the channel and the large-scale axial convective flow. The similar phenomena could take place in artificial hydrological systems, natural geological processes and technological applications

On thermodiffusion influence on the dopant distribution during the freezing of binary liquid column

Актуальность работы определяется необходимостью расширения фундаментальных экспериментальных и теоретических исследований в области макроскопических гидродинамических явлений в многокомпонентных жидких молекулярных смесях. Полученные результаты могут найти свое применение в ряде химических технологий, в том числе существенно изменить взгляды на процессы, связанные с глубокой переработкой, прогнозированием и безопасной утилизацией георесурсов. Цель работы. Изучить явление термодиффузионного разделения сложных по составу жидкостей в тонких каналах при самопроизвольном остывании; сопоставить действие различных механизмов переноса - кратковременной тепловой конвекции, диффузии и термодиффузии на процессы перераспределения компонентов в водно-солевых растворах, заключенных в узких полостях. Предпринятое исследование было выполнено для объяснения возникновения существенной вертикальной стратификации разных по плотности компонентов смеси, что для водно-солевых растворов дает заметное изменение солености среды по высоте канала. Методы исследования. Для достижения поставленных целей использовались экспериментальные и теоретические методы, напрямую имитирующие рассматриваемые процессы: проведено сравнение экспериментальных данных концентрационных проб, взятых в ходе охлаждения и замораживания образцов, с результатами прямого численного моделирования, проведенного методом конечных разностей. Определение температурных полей осуществлялось с помощью метода термопарных измерений. Численная процедура основывалась на полных уравнениях термоконцентрационной конвекции с корректным набором граничных условий. Результаты. Показано, что тепловая конвекция, диффузия и сильная положительная термодиффузия, характерная для водно-солевых растворов, могут привести к заметному продольному разделению жидких смесей в тонких вертикальных каналах при самопроизвольном остывании и последующем замерзании. В основе объяснения неожиданно сильного перераспределения компонентов лежит совместное синхронное действие двух специфических механизмов: термодиффузионного вытеснения примеси в пограничные слои к боковым стенкам столба жидкости и медленного крупномасштабного продольного конвективного течения. Подобные явления могут иметь место в искусственных гидрологических системах, реальных геологических процессах и технологических приложениях.The relevance of the study is caused by the necessity of the extension of fundamental experimental and theoretical research in the field of macroscopic hydrodynamic phenomena in multicomponent liquid molecular mixtures. The results can be used in chemical technologies; they can change our point of view on the processes of deep waste water reclamation and safe utilization of geological resources. The main aim is to investigate the phenomenon of liquid molecular mixtures separation in thin channels by means of thermodiffusion over the self-cooling procedure; to compare different mechanisms of transfer - convection of short duration, diffusion and thermodiffusion - on the process of the components redistribution in the thin columns filled with a water-salt solution. The undertaken investigation has been executed to explain the origination of appreciable vertical stratification of different components of the mixture that gives significant variability of water salinity along the channel height. The methods used in the study: to fulfill the plan of our research the experimental and theoretical methods had been used that simulated physical processes under consideration: experimental data on concentration measurement which were taken during the freezing of the samples had been compared with the results of direct numerical modeling received by the finite difference method. The measurement of temperature fields was realized with the help of thermocouple technique. Numerical procedure was based on the full equations system of thermohaline convection. The results. The authors have shown that thermal convection, diffusion and strong positive thermodiffusion typical for the water-salt solutions can lead to the evident longitudinal division on components in the thin vertical channels filled with liquid mixtures over the selfcooling process and following freezing. The explanation of the strong longitudinal division in the liquid mixtures is based on the joint effect of two different physical mechanisms. There are thermodiffusion displacement of the admixture to the boundary layers of the channel and the large-scale axial convective flow. The similar phenomena could take place in artificial hydrological systems, natural geological processes and technological applications