Modeling Drop-Drop Collision Regimes for Variable Pressures and Viscosities

2012 ◽  
Author(s):  
Eric Loth ◽  
K Ghokulla Haran Krishnan
Keyword(s):  
Drop Collision

Binary collisions of drops of immiscible liquids

2011 ◽  
Vol 690 ◽  
pp. 512-535 ◽  
Author(s):  
Ilia V. Roisman ◽  
Carole Planchette ◽  
Elise Lorenceau ◽  
Günter Brenn
Keyword(s):  
Momentum Balance ◽  
Geometrical Parameters ◽  
Immiscible Liquids ◽  
Free Surfaces ◽  
Geometric Conditions ◽  
Binary Collisions ◽  
Theoretical Predictions ◽  
Drop Collision ◽  
The Impact ◽  
Evolution With Time

AbstractThis experimental and theoretical study is devoted to the investigation of head-on collisions of two drops of immiscible liquids. In the experiments, pairs of drops are made to collide at well-defined kinetic and geometric conditions. The sizes and relative velocity of the colliding drops close to the point of impact are measured by means of image processing. The deformed states after the impact, their evolution with time, and their stability are studied by visualization. The theory considers the dynamics of the rim formed at the edge of a radially spreading lamella due to capillary forces at the free surfaces of the lamella and at the liquid/liquid interface. The equations of the rim formation and motion are obtained from the volume, mass and momentum balance equations which account for the inertial, viscous and capillary effects. The theory predicts the evolution of the main geometrical parameters of the liquid mass formed by the drop collision: thickness of the lamella, diameter, and size of the rim cross-section. The theoretical predictions agree well with the experimental data, although no adjustable parameters are used in the model.

A LATTICE BOLTZMANN APPROACH FOR IMMISCIBLE FLUIDS WITH VERY DIFFERENT VISCOSITIES

2005 ◽  
Vol 16 (09) ◽  
pp. 1409-1435
Author(s):  
LUCIANO MISICI ◽  
SILVIA PALPACELLI
Keyword(s):  
Lattice Boltzmann ◽  
Immiscible Fluids ◽  
Three Dimensions ◽  
Lattice Boltzmann Model ◽  
Reconstruction Method ◽  
Interface Motion ◽  
Qualitative Comparison ◽  
Multi Scale ◽  
Drop Collision ◽  
Boltzmann Model

In this article, a lattice Boltzmann model for two immiscible fluids with same density but a large viscosity difference is developed. The effect of surface tension is included. An indicator function is used to model the interface motion and is updated by a lattice Boltzmann scheme. The macroscopic equation for this function is derived using multi-scale analysis. Numerical results are compared with theoretical and experimental ones for the problem of drop deformation under steady linear flows. A qualitative comparison with results given by a level contour reconstruction method for drop collision in three dimensions is also shown. Other numerical applications, such as flow past obstacles and a falling drop, are presented.

Numerical study on melt drop collision and hydraulic fragmentation during FCI of a nuclear reactor severe accident

2020 ◽  
Vol 370 ◽  
pp. 110862
Author(s):  
Gen Li ◽  
Panpan Wen ◽  
Yupeng Li ◽  
Jinshi Wang ◽  
Weixiong Chen ◽  
...  
Keyword(s):  
Nuclear Reactor ◽  
Numerical Study ◽  
Severe Accident ◽  
Drop Collision

scholarly journals Simulation of the interaction between grain particles and the preserving agent in the roller mill mixing chamber

2020 ◽  
Author(s):  
П.А. Савиных ◽  
В.А. Казаков ◽  
А.М. Мошонкин
Keyword(s):  
Standard Deviation ◽  
Research Center ◽  
Roller Mill ◽  
Storage Technology ◽  
Mixing Chamber ◽  
Drop Collision ◽  
Bacteria And Fungi

Технология консервирования плющеного влажного зерна включает его плющение, консервирование и закладку на герметичное хранение до скармливания. Технологическая операция по химическому консервированию предполагает обработку влажного плющеного зерна консервантом, жидким или порошкообразным, который подавляет микрофлору влажной зерновки, угнетает развитие и размножение имеющихся в ней гнилостных бактерий и споры микрогрибов, тем самым исключая гниение и самосогревание плющеного корма. Целью исследований была разработка схемы плющилки зерна с устройством внесения консерванта и теоретические исследования взаимодействия зерна и консерванта в камере смешивания данной плющилки. В ФГБНУ «ФАНЦ Северо-Востока» разработана плющилка фуражного зерна с устройством для внесения консерванта, новизна конструкции и рабочего процесса которой подтверждена патентами RU № 2399420 и RU № 2628297. Проведено математическое моделирование взаимодействия движущихся под прямым углом навстречу друг другу потоков плющеного зерна и распыляемого на него консерванта в камере смешивания плющилки зерна, позволившее определить вероятность столкновения капель консерванта и частиц зерна, а также количество консерванта, попавшего и поглощённого каждой зерновкой получаемого корма, в зависимости от типа распыляющих консервант форсунок и конструктивных параметров камеры смешивания. Теоретически установлено, что равномерность внесения консерванта (распределение консерванта по зерну), определяемая по среднеквадратическому отклонению, для форсунок с круглым и щелевым распылителем составляет 5,3410–20 и 3,7910–20 соответственно. Исходя из этого, наиболее эффективным для данной конструкции камеры смешивания плющилки является применение форсунки с щелевым отверстием распылителя как обеспечивающего наиболее равномерное распределение консерванта. Storage technology of wet rolled grain consists of rolling, conservation and maintaining of hermetic conditions up to feeding. Grain treatment with liquid or powdered preserving agents inhibits the growth of microorganisms such as bacteria and fungi, preventing rolled forage deterioration and heating. The research was aimed to design a roller mill allowing the application of a preserving agent and conduct the simulation of grain-preservative interaction in the mixing chamber. The team from the Northeastern Federal Agrarian Research Center developed the roller mill enabling the grain treatment by preserving agents (Russian Patents No. 2399420 and 2628297). The simulation was performed on grain and preservative flows moving towards each other at right angle in the mixing chamber. As a result, the probability of preservative drop collision with grain particles was determined as well as the amount of the preservative absorbed by each grain as affected by injector type and mixing chamber parameters. According to the standard deviation, the efficiency of preservative distribution in the grain mass amounted to 5.3410–20 and 3.7910–20 for injectors with circular or slot jets, respectively. The slot injector provided the best distribution of the preservative.

scholarly journals Drop Stream – Immiscible Jet Collisions: Regimes and Fragmentation Mechanisms

2017 ◽  
Author(s):  
Carole Planchette ◽  
Hannes Hinterbichler ◽  
Günter Brenn
Keyword(s):  
Liquid Jet ◽  
Glycerol Solution ◽  
Immiscible Liquids ◽  
Jet Stability ◽  
Fragmentation Mechanisms ◽  
Drop Collision ◽  
New Applications ◽  
Regime Map ◽  
First Time ◽  
Mixed Fragmentation

We investigate the collision of a continuous liquid jet with a regular stream of immiscible droplets. The immiscible liquids, namely silicon oil for the continuous jet and an aqueous glycerol solution for the drop stream, are selected to enable the total wetting of the drops by the jet liquid. Four different regimes are experimentally identified: drops in jet, encapsulation without satellites, encapsulation with satellites from the jet liquid and mixed fragmentation. The drops in jet regime, potentially of great interest for new applications, corresponds to a regular stream of drops embedded in a continuous jet and is described and reported for the first time. Using well known aspects of drop collision and jet stability, we propose to model the transition between the drops in jet regime and the others. Two dimensionless parameters are derived from this analysis which are thus used to produce a simple regime map where the drops in jet regime can be well distinguished from the other outcomes.DOI: http://dx.doi.org/10.4995/ILASS2017.2017.4707 

scholarly journals Aerosol–Cloud Interactions in a Mesoscale Model. Part I: Sensitivity to Activation and Collision–Coalescence

2008 ◽  
Vol 65 (2) ◽  
pp. 289-308 ◽  
Author(s):  
Irena T. Ivanova ◽  
Henry G. Leighton
Keyword(s):  
Mesoscale Model ◽  
High Sensitivity ◽  
Particle Spectrum ◽  
Frontal System ◽  
Aerosol Cloud ◽  
Droplet Concentration ◽  
Particle Activation ◽  
Drop Collision ◽  
Aerosol Sources ◽  
Aerosol Cloud Interactions

Abstract High-resolution numerical simulations of the aerosol–cloud feedbacks are performed with a mesoscale model. The multimodal aerosol species, added to the model, and the cloud species were represented by two spectral moments. The aerosol sources include particle activation, solute transfer between drops due to collision and coalescence of drops, and particle regeneration. A summertime case was simulated consisting of a cold frontal cloud system and a postfrontal stratus. Experiments with both simple and mechanistic activation parameterization of aerosol and with one and two aerosol modes were performed. Verification was made of the stratus properties against measurements taken during the Radiation Aerosol and Cloud Experiment (RACE). The results demonstrate a significant sensitivity of the stratus and of the frontal system to the aerosol and a moderate impact on the particle spectrum of drop collision–coalescence. The stratus simulation with mechanistic activation and unimodal aerosol showed the best agreement of droplet concentration with the observations, and the simulations with mechanistic activation and a bimodal aerosol and with simple activation underestimated the droplet concentration. A similar high sensitivity was found for the frontal precipitation intensity. Drop collision–coalescence in the frontal system was found to have an impact on the particle mean radius whose magnitude amounted to 10% and 15% for one and multiple cloud cycles, respectively. This impact was also found to be highly variable in space. The modified particle spectrum, following activation in clouds, was found to increase droplet concentration.

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