%0 Conference Paper %1 ibach2022numerical %A Ibach, Matthias %A Vaikuntanathan, Visakh %A Arad, Alumah %A Katoshevski, David %A Greenberg, J. B. %A Schulte, K. %A Weigand, B. %D 2022 %K PN1 misc EXC2075 PN1-2B %T Numerical Investigation of Multiple Droplet Streams and the Effect on Grouping Behavior %X The exact knowledge of droplet clustering or grouping is important in many technical applications , such as fuel injection, ink-jet printing or in medical nebulizers. Despite their relevance, the fundamentals of grouping processes are yet to be fully understood. Recent studies comprise the experimental and numerical investigation of single monodisperse streams in well-defined droplet arrangements. Moving towards more complex configurations, such as multiple streams in close proximity, is a challenging task experimentally. This study aims at bridging this gap numerically with the aid of the in-house multiphase code Free Surface 3D to assess the effect of multiple droplet streams on grouping behavior. Three streams of droplets in a coplanar arrangement are simulated for which the center stream is compared to a single reference stream without the influence of neighboring droplets. To determine the impact of the outer streams on the center stream regarding grouping time, relative droplet velocity, drag forces as well as pressure and shear stress distribution, the following input parameters are changed systematically: the initial lateral distance to the center stream and the initial Reynolds number. Results show that the presence of neighboring streams with a lateral distance of less than 5 droplet diameters has a significant influence on the grouping behavior of the central stream. The process can be divided into a first part (I) where the outer streams confine the interaction with the surroundings, slowing down grouping tendencies and reducing drag forces in the middle stream; and a second part (II) where the coalescence of the outer streams imposes a substantial disturbance on the middle stream leading to an abrupt increase in the forces acting upon the droplets. Additionally, the lateral drift of the outside streams is compared qualitatively to literature studies and shows good agreement. For lateral distances of more than 10 droplet diameters, the interaction of the streams is negligible and the behavior of a single, isolated stream is retained.

@inproceedings{ibach2022numerical, abstract = {The exact knowledge of droplet clustering or grouping is important in many technical applications , such as fuel injection, ink-jet printing or in medical nebulizers. Despite their relevance, the fundamentals of grouping processes are yet to be fully understood. Recent studies comprise the experimental and numerical investigation of single monodisperse streams in well-defined droplet arrangements. Moving towards more complex configurations, such as multiple streams in close proximity, is a challenging task experimentally. This study aims at bridging this gap numerically with the aid of the in-house multiphase code Free Surface 3D to assess the effect of multiple droplet streams on grouping behavior. Three streams of droplets in a coplanar arrangement are simulated for which the center stream is compared to a single reference stream without the influence of neighboring droplets. To determine the impact of the outer streams on the center stream regarding grouping time, relative droplet velocity, drag forces as well as pressure and shear stress distribution, the following input parameters are changed systematically: the initial lateral distance to the center stream and the initial Reynolds number. Results show that the presence of neighboring streams with a lateral distance of less than 5 droplet diameters has a significant influence on the grouping behavior of the central stream. The process can be divided into a first part (I) where the outer streams confine the interaction with the surroundings, slowing down grouping tendencies and reducing drag forces in the middle stream; and a second part (II) where the coalescence of the outer streams imposes a substantial disturbance on the middle stream leading to an abrupt increase in the forces acting upon the droplets. Additionally, the lateral drift of the outside streams is compared qualitatively to literature studies and shows good agreement. For lateral distances of more than 10 droplet diameters, the interaction of the streams is negligible and the behavior of a single, isolated stream is retained.}, added-at = {2024-03-26T11:56:40.000+0100}, author = {Ibach, Matthias and Vaikuntanathan, Visakh and Arad, Alumah and Katoshevski, David and Greenberg, J. B. and Schulte, K. and Weigand, B.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/209790ede6b4aafffa5bf6d3b6c1591f0/exc2075}, eventtitle = {ILASS-Europe 2022, 31th Conference on Liquid Atomization and Spray Systems, 6-8 September 2022}, interhash = {08e3b351a2b34ac10a959b610633e473}, intrahash = {09790ede6b4aafffa5bf6d3b6c1591f0}, keywords = {PN1 misc EXC2075 PN1-2B}, timestamp = {2024-03-26T11:56:40.000+0100}, title = {Numerical Investigation of Multiple Droplet Streams and the Effect on Grouping Behavior}, venue = {Tel-Aviv (Virtual)}, year = 2022 }