Dirk Gründing

Dr.-Ing. Dirk Gründing

+49 6151 16-21470
+49 6151 16-72022

Alarich-Weiss-Straße 10
64287 Darmstadt

Office: L2|06 412

More information

When looking out of a window on a rainy day, one can observe droplets sliding down the glass. Similar phenomena involved with the sliding of a droplet can be encountered in nature and a wide variety of industrial applications. Among these are e.g. steel casting, injection modeling, surface coating, printing technologies or flow through microfluidic devices. Just as with the droplet, the liquid-gas interface in these applications forms a specific angle with the surface on which the liquid is moving – the so called contact angle. This angle influences the shape of the interface and consequently the complete hydrodynamics of the problem. In addition, contaminants usually present in the liquid may act as surface active agents (surfactants), and can have an additional significant effect on the hydrodynamics of the flow. To include the contact line dynamics in modern product development processes, the simulation of such phenomena is desirable.

The interaction of the two phases is simulated utilizing the Open Field Operation And Manipulation library (OpenFOAM). The flow of the two fluids and their interaction with a surface is simulated by an interface tracking method [1]. Thereby, the interface between the two phases is represented by a part of the computational unstructured mesh. This means that the complete mesh has to be moved to follow the movement of the physical interface. Such an approach results in an arbitrary lagrangian eulerian (ALE) method capable to simulate the air and liquid phase. The interface mesh is the outstanding feature of this approach as it can be used to simulate the evolution of surfactants present on the liquid gas interface by means of a finite area method. The goal of this project is to extend the existing OpenFOAM functionality to simulate contact phenomena. This includes, in addition to the usual complexities in simulating multiphase flows, dealing with contact line specific problems such as an extreme mesh resolution near the contact line. Furthermore, a discrepancy between a no slip boundary condition at the liquid-surface boundary and a moving contact line as well as possibly resulting pressure singularities while have to be dealt with. In addition, the approach has to provide a variety contact angle models [2].

For the implementation of the features mentioned above, modern software engineering tools such as GIT, Confluence, and Jira are employed to version, document, and organize the developing process.

Fig. 1: Comparison of velocity profiles of a spreading droplet with (right) and without (left) surfactant Image: M.Sc. Dirkk Gründing
Fig. 1: Comparison of velocity profiles of a spreading droplet with (right) and without (left) surfactant Image: M.Sc. Dirkk Gründing

Acknowledgements

I gratefully acknowledge financial support from the Deutsche Forschungsgemeinschaft received within the scope of SFB 1194.

Project References

[1] Tuković, Z. and Jasak, H. (2012). A moving mesh finite volume interface tracking method for surface tension dominated interfacial fluid flow. Computers & Fluids, 55:70-84

[2] Sui, Y., Ding, H. and Spelt, P. D. (2014). Numerical Simulations of Flows with Moving Contact Lines. Annual Review of Fluid Mechanics. 46:97–119

Publications

[E1] D.M. Gründing, S. Fleckenstein and D. Bothe. A Subgrid-Scale Model for Reactive Concentration Boundary Layers for 3D Mass Transfer Simulations with Deformable Fluid Interfaces, International Journal of Heat and Mass Transfer.

Acknowledgements

I gratefully acknowledge financial support from the Deutsche Forschungsgemeinschaft received within the scope of SPP1740 under the grant of BO1879/13-1.

Teaching:

winter term 2016

  • Assistant for “Mathematics for Electrical Engineers 1” (ca. 800 students)

summer term 2016:

  • Coordinating assistant for “Mathematical Modeling of Fluid Interfaces” (ca. 15 students)
  • Coordinating assistant for “Mathematics for Electrical Engineers 3” (ca. 100 students)
  • Assistant for “Mathematics for Electrical Engineers 2” (ca. 500 students)

summer term 2015:

  • Coordinating assistant for “Mathematical Modeling of Fluid Interfaces” (ca. 15 students)
  • Coordinating assistant for “Linear Algebra 1&2” (ca. 200 students) winter term 2015/2016:

winter term 2015:

  • Coordinating assistant for “Mathematics for Electrical Engineers 3” (ca. 450 students)

Additional responsibilities

Representative of PhD students (ca. 25) in the SFB 1194

Organisation of internal seminar of the MMA group

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