Transfer of Matter at the Initial Stage of Cavity Formation in the Impact Mode of Merging a Freely Falling Drop


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Using the methods of scientific photo and videography, the geometry of the flow pattern and the distribution of matter of a free-falling liquid drop in a resting target fluid at the initial stage of cavity formation was recorded. The experiments were carried out in the range of parameters of the impact mode of coalescence, when the kinetic energy of the drop exceeds its available potential surface energy (APSE). To register a color image, the flow pattern was simultane-ously illuminated by several sources including matrix LED and fiber-optic sources of constant light. The planning and interpretation of the experiments results were carried out taking into account the properties of the complete solutions of the fluid mechanics fundamental equations system, taking into account the transfer and conversion of energy. The experiments were car-ried out with a single drop of potassium permanganate solution falling into water. In the im-pact mode, the drop begins to lose continuity at the initial contact, when a veil and thin jets are formed, the velocity of which exceeds the drop contact velocity. From the tops of the jets, small droplets are thrown into the air, the size of which grows with time. On the surface of the liquid, the jets leave colored traces that form line and mesh structures. Part of the jets pene-trates through the cavity bottom and forms an intermediate layer. In it, the jets are separated by interfaces of the target fluid. The processes of molecular diffusion equalize the density differ-ence and form an intermediate layer, which is outlined by sharp boundaries, under the cavity.

drop, impact, experiment, fine structure, cavity, substance transfer

DOI: http://doi.org/10.33257/PhChGD.24.5.1068


Volume 24, issue 5, 2023 year


Перенос вещества на начальном этапе формирования каверны в импактном режиме слияния свободно падающей капли

Методами научной фото- и видеографии проведена регистрация геометрии картины течения и рас-пределения вещества свободно падающей капли жидкости в покоящейся принимающей жидкости на начальном этапе формирования каверны. Опыты выполнены в диапазоне параметров импактного режима слияния, когда кинетическая энергия капли превышает ее доступную потенциальную по-верхностную энергию (ДППЭ). Для регистрации цветного изображения картина течения одновре-менно освещалась несколькими источниками – матричными светодиодными и волоконнооптиче-скими источниками постоянного света. Планирование и интерпретация результатов опытов проводились с учетом свойств полных решений системы фундаментальных уравнений, механики жидкостей, учитывающих перенос и конверсию энергии. Опыты выполнены с единичной каплей раствора перманганата калия, падающей в воду. В импактном режиме капля начинает терять сплошность при первичном контакте, когда образуется пелена и тонкие струйки, скорость которых превосходит контактную скорость капли. С вершин струек в воздух выбрасываются капельки, раз-меры которых растут со временем. На поверхности жидкости струйки оставляют окрашенные сле-ды, формирующие линейчатые и сетчатые структуры. Часть струек пронизывает дно и стенки ка-верны и образует промежуточный слой. В нем струйки разделены прослойками принимающей жидкости. Процессы молекулярной диффузии выравнивают разность плотностей и формируют под каверной промежуточный слой, очерченный четкими границами.

капля, импакт, эксперимент, тонкая структура, перенос вещества

DOI: http://doi.org/10.33257/PhChGD.24.5.1068


Volume 24, issue 5, 2023 year



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