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DFG: GRK 2160 (DROPIT)

DFG: GRK 2160 (DROPIT)

Droplet Interaction Technologies

Leitung:
Prof. Dr. Thomas Ertl

Assoziierter Mitarbeiter:
Alexander Straub, M.Sc.

Gefördert durch:
Deutsche Forschungsgemeinschaft (DFG)

Laufzeit:
2016 - 2021

Projektwebseite:
project.uni-stuttgart.de/dropit

In diesem internationalen Graduiertenkolleg übernehmen die Doktoranden die Erforschung von Phänomenen der Tropfeninteraktion. Das Ziel ist der Erkenntnisgewinn, welchen Effekt Phänomene im mikroskopischen Bereich auf die Flusseigenschaften im makroskopischen Bereich haben. Dafür ist das DROPIT-Projekt in drei thematische Bereiche aufgeteilt, welche die jeweiligen Interaktionen von Flüssigkeiten mit anderen Medien erforschen. Diese sind Tropfen-Gas-Interaktionen, Tropfen-Wand-Interaktionen und Tropfen-Flüssigkeit-Interaktionen. An diesem interdisziplinären und internationalen Projekt nehmen darüber hinaus mehrere Institute der Universitäten in Stuttgart, Bergamo und Trento teil, die an den Forschungsaufgaben experimentell, numerisch, theoretisch und visuell arbeiten.

Großer Wert wird zudem der Ausbildung der Doktoranden beigemessen. Zusätzlich zu Workshops und Seminaren werden international anerkannte Wissenschaftler eingeladen, um gemeinsam in einer Summer School zu forschen. Eingegliedert ist das Projekt außerdem in den Graduiertenschule der jeweiligen Universität, für die Universität Stuttgart also im GRADUS. Weiterhin haben die Doktoranden die Möglichkeit Teil der Graduiertenschule des Excellenzcluster SimTech zu sein.

Die Rolle des VIS(US) in dieser Zusammenarbeit ist die Visualisierung von Eigenschaften an Topfenoberflächen. Dazu gehört die Visualisierung von Fluss in porösen Medien, sowie die Visualisierung von Oberflächendeformation und tropfenlokalem Fluss. Dies geschieht im Teilprojekt C4: Visualization of drop-liquid interaction.

Für weitere Informationen, besuchen Sie die Projektseite unter
project.uni-stuttgart.de/dropit.

Publikationen

2023
1. Straub, Alexander ; Karch, Grzegorz K. ; Steigerwald, Jonas ; Sadlo, Filip ; Weigand, Bernhard ; Ertl, Thomas: Visual Analysis of Interface Deformation in Multiphase Flow. In: Journal of Visualization, Journal of Visualization. Bd. 26 (2023), Nr. 6, S. 1321–1338
  Zusammenfassung
  In multiphase flows, the evolution of fluid-fluid interfaces is of interest in many applications. In addition to fluid dynamic forces governing the flow in the entire volume, surface tension determines droplet interfaces. Here, the analysis of interface kinematics can help in the investigation of interface deformation and the identification of potential breakups. To this end, we developed a visualization technique using metric and shape tensors to analyze interface stretching and bending. For interface stretching, we employ the eigenpairs of the metric tensor defined for the deformation rate of the fluid surface. For interface bending, we present a technique that locally captures the interface curvature change in terms of a shape tensor, extracting its principal directions and curvatures. We then visualize interface deformation by combining both representations into a novel glyph design. We apply our method to study multiphase flow simulations with particular emphasis on interface effects. These include the interplay between fluid dynamics and surface tension forces leading to breakup processes following droplet collisions, as well as droplet-droplet interactions of different fluids where Marangoni convection along the surface is explicitly taken into account.
  BibTeX
  @article{straub2023visual, abstract = {In multiphase flows, the evolution of fluid-fluid interfaces is of interest in many applications. In addition to fluid dynamic forces governing the flow in the entire volume, surface tension determines droplet interfaces. Here, the analysis of interface kinematics can help in the investigation of interface deformation and the identification of potential breakups. To this end, we developed a visualization technique using metric and shape tensors to analyze interface stretching and bending. For interface stretching, we employ the eigenpairs of the metric tensor defined for the deformation rate of the fluid surface. For interface bending, we present a technique that locally captures the interface curvature change in terms of a shape tensor, extracting its principal directions and curvatures. We then visualize interface deformation by combining both representations into a novel glyph design. We apply our method to study multiphase flow simulations with particular emphasis on interface effects. These include the interplay between fluid dynamics and surface tension forces leading to breakup processes following droplet collisions, as well as droplet-droplet interactions of different fluids where Marangoni convection along the surface is explicitly taken into account.}, author = {Straub, Alexander and Karch, Grzegorz K. and Steigerwald, Jonas and Sadlo, Filip and Weigand, Bernhard and Ertl, Thomas}, doi = {https://doi.org/10.1007/s12650-023-00939-x}, journal = {Journal of Visualization}, number = 6, pages = {1321-1338}, title = {Visual Analysis of Interface Deformation in Multiphase Flow}, volume = 26, year = 2023 }
  DOI
  https://doi.org/10.1007/s12650-023-00939-x
2022
1. Straub, Alexander ; Boblest, Sebastian ; Karch, Grzegorz K. ; Sadlo, Filip ; Ertl, Thomas: Droplet-Local Line Integration for Multiphase Flow. In: 2022 IEEE Visualization and Visual Analytics (VIS), 2022 — ISBN 978-1-6654-8812-9, S. 135–139
  Zusammenfassung
  Line integration of stream-, streak-, and pathlines is widely used and popular for visualizing single-phase flow. In multiphase flow, i.e., where the fluid consists, e.g., of a liquid and a gaseous phase, these techniques could also provide valuable insights into the internal flow of droplets and ligaments and thus into their dynamics. However, since such structures tend to act as entities, high translational and rotational velocities often obfuscate their detail. As a remedy, we present a method for deriving a droplet-local velocity field, using a decomposition of the original velocity field removing translational and rotational velocity parts, and adapt path- and streaklines. Generally, the resulting integral lines are thus shorter and less tangled, which simplifies their analysis. We demonstrate and discuss the utility of our approach on droplets in two-phase flow data and visualize the removed velocity parts employing glyphs for context.
  BibTeX
  @inproceedings{straub2022dropletlocal, abstract = {Line integration of stream-, streak-, and pathlines is widely used and popular for visualizing single-phase flow. In multiphase flow, i.e., where the fluid consists, e.g., of a liquid and a gaseous phase, these techniques could also provide valuable insights into the internal flow of droplets and ligaments and thus into their dynamics. However, since such structures tend to act as entities, high translational and rotational velocities often obfuscate their detail. As a remedy, we present a method for deriving a droplet-local velocity field, using a decomposition of the original velocity field removing translational and rotational velocity parts, and adapt path- and streaklines. Generally, the resulting integral lines are thus shorter and less tangled, which simplifies their analysis. We demonstrate and discuss the utility of our approach on droplets in two-phase flow data and visualize the removed velocity parts employing glyphs for context.}, author = {Straub, Alexander and Boblest, Sebastian and Karch, Grzegorz K. and Sadlo, Filip and Ertl, Thomas}, booktitle = {2022 IEEE Visualization and Visual Analytics (VIS)}, doi = {10.1109/VIS54862.2022.00036}, isbn = {978-1-6654-8812-9}, pages = {135-139}, preprinturl = {https://arxiv.org/abs/2208.11475}, title = {Droplet-Local Line Integration for Multiphase Flow}, url = {https://doi.org/10.1109/VIS54862.2022.00036}, year = 2022 }
  Link
  https://doi.org/10.1109/VIS54862.2022.00036
  DOI
  10.1109/VIS54862.2022.00036
2021
1. Straub, Alexander ; Karch, Grzegorz K. ; Sadlo, Filip ; Ertl, Thomas: Implicit Visualization of 2D Vector Field Topology for Periodic Orbit Detection. In: Topological Methods in Data Analysis and Visualization VI : Springer International Publishing, 2021 — ISBN 978-3-030-83500-2, S. 159–180
  Zusammenfassung
  We present implicit visualization of 2D vector field topology, and show its utility for validating and guiding approaches for periodic orbit extraction. Instead of following the traditional approach by explicit extraction of the topological skeleton, we investigate its implicit visualization by approaches that label the regions that are separated by the skeleton. While such approaches perform well for gradient fields, they fail, in particular, to visualize periodic orbits. This motivates us to complement the label-based approach with a closely related distance-based metric. We show that our approach is able to reveal periodic orbits, also in configurations in which the state-of-the-art techniques for periodic orbit extraction fail, and demonstrate their utility for interactive extraction of all periodic orbits of a 2D vector field.
  BibTeX
  @incollection{straub2021implicit, abstract = {We present implicit visualization of 2D vector field topology, and show its utility for validating and guiding approaches for periodic orbit extraction. Instead of following the traditional approach by explicit extraction of the topological skeleton, we investigate its implicit visualization by approaches that label the regions that are separated by the skeleton. While such approaches perform well for gradient fields, they fail, in particular, to visualize periodic orbits. This motivates us to complement the label-based approach with a closely related distance-based metric. We show that our approach is able to reveal periodic orbits, also in configurations in which the state-of-the-art techniques for periodic orbit extraction fail, and demonstrate their utility for interactive extraction of all periodic orbits of a 2D vector field.}, author = {Straub, Alexander and Karch, Grzegorz K. and Sadlo, Filip and Ertl, Thomas}, booktitle = {Topological Methods in Data Analysis and Visualization VI}, doi = {10.1007/978-3-030-83500-2_9}, editor = {Hotz, Ingrid and Bin Masood, Talha and Sadlo, Filip and Tierny, Julien}, isbn = {978-3-030-83500-2}, pages = {159-180}, publisher = {Springer International Publishing}, series = {Mathematics and Visualization}, title = {Implicit Visualization of 2D Vector Field Topology for Periodic Orbit Detection}, url = {https://doi.org/10.1007/978-3-030-83500-2_9}, year = 2021 }
  Link
  https://doi.org/10.1007/978-3-030-83500-2_9
  DOI
  10.1007/978-3-030-83500-2_9
2020
1. Straub, Alexander ; Ertl, Thomas: Visualization Techniques for Droplet Interfaces and Multiphase Flow. In: Droplet Interactions and Spray Processes. Bd. 121 : Springer International Publishing, 2020 — ISBN 978-3-030-33338-6, S. 203–214
  Zusammenfassung
  The analysis of large multiphase flow simulation data poses an interesting and complex research question, which can be addressed with interactive visualization techniques, as well as semi-automated analysis processes. In this project, the focus lies on the investigation of forces governing droplet evolution. Therefore, our proposed methods visualize and allow the analysis of droplet deformation and breakup, droplet behavior and evolution, and droplet-internal flow. By deriving quantities for interface stretching and bending, we visualize and analyze the influence of surface tension force on breakup dynamics, and forces induced by Marangoni convection. Using machine learning to train a simple model for the prediction of physical droplet properties, we provide a visual analysis framework that can be used to analyze large simulation data. Computing droplet-local velocity fields where every droplet is observed separately in its own frame of reference, we create local, interpretable visualizations of flow within droplets, allowing for the investigation of the influence of flow dynamics on droplet evolution.
  BibTeX
  @incollection{Straub2020dropit, abstract = {The analysis of large multiphase flow simulation data poses an interesting and complex research question, which can be addressed with interactive visualization techniques, as well as semi-automated analysis processes. In this project, the focus lies on the investigation of forces governing droplet evolution. Therefore, our proposed methods visualize and allow the analysis of droplet deformation and breakup, droplet behavior and evolution, and droplet-internal flow. By deriving quantities for interface stretching and bending, we visualize and analyze the influence of surface tension force on breakup dynamics, and forces induced by Marangoni convection. Using machine learning to train a simple model for the prediction of physical droplet properties, we provide a visual analysis framework that can be used to analyze large simulation data. Computing droplet-local velocity fields where every droplet is observed separately in its own frame of reference, we create local, interpretable visualizations of flow within droplets, allowing for the investigation of the influence of flow dynamics on droplet evolution.}, author = {Straub, Alexander and Ertl, Thomas}, booktitle = {Droplet Interactions and Spray Processes}, doi = {10.1007/978-3-030-33338-6_16}, editor = {Lamanna, Grazia and Tonini, Simona and Cossali, Gianpietro Elvio and Weigand, Bernhard}, isbn = {978-3-030-33338-6}, pages = {203-214}, publisher = {Springer International Publishing}, series = {Fluid Mechanics and its Applications}, title = {Visualization Techniques for Droplet Interfaces and Multiphase Flow}, url = {https://dx.doi.org/10.1007/978-3-030-33338-6_16}, volume = 121, year = 2020 }
  Link
  https://dx.doi.org/10.1007/978-3-030-33338-6_16
  DOI
  10.1007/978-3-030-33338-6_16
2019
1. Straub, Alexander ; Heinemann, Moritz ; Ertl, Thomas: Visualization and Visual Analysis for Multiphase Flow. In: Proceedings of the DIPSI Workshop 2019. Droplet Impact Phenomena & Spray Investigations : Università degli studi di Bergamo, 2019 — ISBN 978-88-97253-02-0, S. 25–27
  Zusammenfassung
  When investigating multiphase flow, important aspects to consider are free surfaces, their influence on coherence and breakup of droplets, and the influence of droplet-local flow on droplet shape and topology. To this end, we want to provide visualization techniques and the means for visual analysis of complex multiphase flow data. This data is obtained from direct numerical simulations (DNS), in this case from the solver Free Surface 3D (FS3D), which solves the Navier-Stokes equations for incompressible multiphase flow. The data consists of a velocity field and a volume of fluid (VOF) field, whereas the latter can be used to reconstruct the fluid interface. In the following, we will present three projects, which all aim at using visualization for gaining understanding of phenomena related to flow in droplets and forces acting on the free surfaces.
  BibTeX
  @inproceedings{straub2019visualization, abstract = {When investigating multiphase flow, important aspects to consider are free surfaces, their influence on coherence and breakup of droplets, and the influence of droplet-local flow on droplet shape and topology. To this end, we want to provide visualization techniques and the means for visual analysis of complex multiphase flow data. This data is obtained from direct numerical simulations (DNS), in this case from the solver Free Surface 3D (FS3D), which solves the Navier-Stokes equations for incompressible multiphase flow. The data consists of a velocity field and a volume of fluid (VOF) field, whereas the latter can be used to reconstruct the fluid interface. In the following, we will present three projects, which all aim at using visualization for gaining understanding of phenomena related to flow in droplets and forces acting on the free surfaces.}, address = {Bergamo, Italy}, author = {Straub, Alexander and Heinemann, Moritz and Ertl, Thomas}, booktitle = {Proceedings of the DIPSI Workshop 2019. Droplet Impact Phenomena & Spray Investigations}, doi = {10.6092/DIPSI2019_pp25-27}, editor = {Cossali, Gianpietro and Tonini, Simona}, eventdate = {May, 2018}, eventtitle = {DIPSI Workshop 2018 - Droplet Impact Phenomena & Spray Investigations}, isbn = {978-88-97253-02-0}, language = {English}, organization = {Università degli studi di Bergamo}, pages = {25-27}, publisher = {Università degli studi di Bergamo}, title = {Visualization and Visual Analysis for Multiphase Flow}, url = {https://dx.doi.org/10.6092%2FDIPSI2019_pp25-27}, venue = {Bergamo, Italy}, year = 2019 }
  Link
  https://dx.doi.org/10.6092%2FDIPSI2019_pp25-27
  DOI
  10.6092/DIPSI2019_pp25-27
2018
1. Straub, Alexander ; Karch, Grzegorz Karol ; Boblest, Sebastian ; Kaufmann, Jonas ; Sadlo, Filip ; Weigand, Bernhard ; Ertl, Thomas: Visual Analysis of Interface Deformation in Multiphase Flow. In: Proceedings of the DIPSI Workshop 2018. Droplet Impact Phenomena & Spray Investigations : Università degli studi di Bergamo, 2018 — ISBN 978-88-97413-27-1, S. 45–47
  Zusammenfassung
  This project aims at investigating droplet-related phenomena, especially the influence of forces acting on the surface. To this end, we visualize interface deformation using two quantities: interface stretching and interface bending. This allows the visual analysis of droplet behavior and interface-related forces, such as the surface tension force and forces induced by Marangoni convection. For the latter, we show an application case for debugging and aiding the implementation of the Marangoni term in the solver Free Surface 3D (FS3D). Furthermore, we demonstrate the usefulness of our approach for prediction of droplet breakup.
  BibTeX
  @inproceedings{straub2018visual, abstract = {This project aims at investigating droplet-related phenomena, especially the influence of forces acting on the surface. To this end, we visualize interface deformation using two quantities: interface stretching and interface bending. This allows the visual analysis of droplet behavior and interface-related forces, such as the surface tension force and forces induced by Marangoni convection. For the latter, we show an application case for debugging and aiding the implementation of the Marangoni term in the solver Free Surface 3D (FS3D). Furthermore, we demonstrate the usefulness of our approach for prediction of droplet breakup.}, address = {Bergamo, Italy}, author = {Straub, Alexander and Karch, Grzegorz Karol and Boblest, Sebastian and Kaufmann, Jonas and Sadlo, Filip and Weigand, Bernhard and Ertl, Thomas}, booktitle = {Proceedings of the DIPSI Workshop 2018. Droplet Impact Phenomena & Spray Investigations}, doi = {10.6092/DIPSI2018_pp45-47}, editor = {Cossali, Gianpietro Elvio and Tonini, Simona}, eventdate = {May, 2018}, eventtitle = {DIPSI Workshop 2018 - Droplet Impact Phenomena & Spray Investigations}, isbn = {978-88-97413-27-1}, language = {English}, organization = {Università degli studi di Bergamo}, pages = {45-47}, publisher = {Università degli studi di Bergamo}, title = {Visual Analysis of Interface Deformation in Multiphase Flow}, url = {http://dx.doi.org/10.6092%2FDIPSI2018_pp45-47}, venue = {Bergamo, Italy}, year = 2018 }
  Link
  http://dx.doi.org/10.6092%2FDIPSI2018_pp45-47
  DOI
  10.6092/DIPSI2018_pp45-47
2017
1. Karch, Grzegorz Karol ; Straub, Alexander ; Sadlo, Filip ; Ertl, Thomas: Implicit Visualization of Vector Field Topology. In: Proceedings of TopoInVis, 2017. — Reviewed abstract
  - Zusammenfassung
  - BibTeX
  Zusammenfassung
  Vector field topology is traditionally visualized by explicit extraction of graphical objects that represent the topological skeleton, including critical points, periodic orbits, and the invariant manifolds converging to those in forward or reverse time. In this work, we present implicit visualization of vector field topology by means of derived scalar fields. We obtain these fields by seeding a forward and a reverse streamline at each of their samples, and determining which critical point, periodic orbit, or solid boundary they converge to. This provides a segmentation of the domain with respect to regions of qualitatively similar streamline behavior, and thus its topological structure.We present an adaptive sampling strategy of the fields, together with an approach to determine their convergence with respect to streamline integration. Using 2D and 3D fields, we exemplify the utility and interpretation of our approach.
  BibTeX
  @inproceedings{karch2017implicit, abstract = {Vector field topology is traditionally visualized by explicit extraction of graphical objects that represent the topological skeleton, including critical points, periodic orbits, and the invariant manifolds converging to those in forward or reverse time. In this work, we present implicit visualization of vector field topology by means of derived scalar fields. We obtain these fields by seeding a forward and a reverse streamline at each of their samples, and determining which critical point, periodic orbit, or solid boundary they converge to. This provides a segmentation of the domain with respect to regions of qualitatively similar streamline behavior, and thus its topological structure.We present an adaptive sampling strategy of the fields, together with an approach to determine their convergence with respect to streamline integration. Using 2D and 3D fields, we exemplify the utility and interpretation of our approach.}, author = {Karch, Grzegorz Karol and Straub, Alexander and Sadlo, Filip and Ertl, Thomas}, booktitle = {Proceedings of TopoInVis}, note = {Reviewed abstract}, title = {Implicit Visualization of Vector Field Topology}, year = 2017 }

DFG: GRK 2160 (DROPIT)

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DFG: GRK 2160 (DROPIT)

Publikationen

2023

Zusammenfassung

BibTeX

DOI

2022

Zusammenfassung

BibTeX

Link

DOI

2021

Zusammenfassung

BibTeX

Link

DOI

2020

Zusammenfassung

BibTeX

Link

DOI

2019

Zusammenfassung

BibTeX

Link

DOI

2018

Zusammenfassung

BibTeX

Link

DOI

2017

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BibTeX

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