Kathrin Schulte

Kathrin Schulte
University of Stuttgart · Institute of Aerospace Thermodynamics

Dr.-Ing.

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35
Publications
3,421
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315
Citations

Publications

Publications (35)
Chapter
In-air microfluidics became a new method for technical production processes with ultra-high throughput formerly performed in micro channels. Direct Numerical Simulations (DNS) provide a valuable contribution for the fundamental understanding of multiphase flow and later application design. This chapter presents a feasibility study with first DNS re...
Article
Full-text available
Single droplet impacts onto thin wall-films are a common phenomenon in many applications. For sufficiently high impact velocities, the droplet impact process consists of three phases, i.e., initial contact stage, droplet deformation with radial momentum transfer inducing an upward rising lamella, and crown propagation. Here, we present the results...
Article
This paper presents a particle-based visualization approach for finite-time analysis of the connectivity of fluid portions in multiphase flow, i.e., the evolution of the droplets in volume of fluid simulations. We address the Lagrangian inconsistency between the interpolated flow field and the interpolated volume of fluid field by a correction appr...
Article
Full-text available
Spray impacts can be found in several technical applications and consist of many single droplets, which impact under different trajectories on wetted walls. This study investigates the asymmetric crown morphology resulting from an oblique impact (α= 60°) of a single droplet on a horizontal and quiescent wall film of the same liquid. A droplet gener...
Article
Equally sized droplets made of the same liquid are known to either bounce, coalesce, or separate under collision. Comparable outcomes are observed for immiscible liquids with bouncing, encapsulation instead of coalescence, and separation with two or more daughter droplets. While the transitions between these regimes have been described, the liquid...
Article
This paper presents an advanced Volume of Fluid (VOF) method that enables performant three dimensional Direct Numerical Simulations (DNS) of the interaction of two immiscible fluids in a gaseous environment with large topology changes, e.g., binary droplet collisions. One of the challenges associated with the introduction of a third immiscible pha...
Conference Paper
Full-text available
Droplet impacts on a liquid film can be found in several technical and environmental applications. Besides the extensive research on normal, i.e. 90°, droplet impact on a wetted wall much less is known about the oblique impact, which in experiments is often realized with a flowing liquid film on an inclined wall. This study, however, presents an ex...
Article
This paper presents an efficient algorithm for the sequential positioning, also called nested dissection, of two planes in an arbitrary polyhedron. Two planar interfaces are positioned such that the first plane truncates a given volume from this arbitrary polyhedron and the next plane truncates a second given volume from the residual polyhedron. Th...
Preprint
Full-text available
Head-on collisions of two immiscible liquid droplets lead to a collision complex, which may either remain stable in the form of a single compound drop, or fragment into two main daughter droplets. This paper investigates the liquid distribution developing in the two daughter droplets and which can be of three types. Either two encapsulated droplets...
Preprint
Full-text available
An advanced Volume of Fluid (VOF) method is presented that enables performant three-dimensional Direct Numerical Simulations (DNS) of the interaction of two immiscible fluids in a gaseous environment with large topology changes, e.g., binary droplet collisions. One of the challenges associated with the introduction of a third immiscible phase into...
Preprint
Full-text available
In-air microfluidics became a new method for technical production processes with ultra-high throughput formerly performed in micro channels. Direct Numerical Simulations (DNS) provide a valuable contribution for the fundamental understanding of multiphase flow and later application design. This chapter presents a feasibility study with first DNS re...
Conference Paper
Full-text available
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 monodisp...
Chapter
Full-text available
The complexity of binary droplet collisions strongly increases in case of immiscible liquids with the occurrence of triple lines or for high energetic collisions, where strong rim instabilities lead to the spattering of satellite droplets. To cope with such cases, the Volume of Fluid method is extended by an efficient interface reconstruction, also...
Chapter
Full-text available
A fundamental understanding of droplet dynamics is important for the prediction and optimization of technical systems involving drops and sprays. The Collaborative Research Center (CRC) SFB-TRR 75 was established in January 2010 to focus on the dynamics of basic drop processes, and in particular on processes involving extreme ambient conditions, fo...
Preprint
We present a new topological connection method for the local bilinear computation of Jacobi sets that improves the visual representation while preserving the topological structure and geometric configuration. To this end, the topological structure of the local bilinear method is utilized, which is given by the nerve complex of the traditional piece...
Conference Paper
Full-text available
The tendency of convening and coalescing of initially distant droplets, called droplet grouping, can influence the final droplet size distribution, evaporation rates or final settling points. To better understand the factors which govern droplet grouping mechanisms, reliable direct numerical simulations are beneficial. Previous numerical studies ha...
Preprint
Full-text available
This paper introduces an efficient algorithm for the sequential positioning (or nested dissection) of two planar interfaces in an arbitrary polyhedron, such that, after each truncation, the respectively remaining polyhedron admits a prescribed volume. This task, among others, is frequently encountered in the numerical simulation of three-phase flow...
Preprint
Full-text available
The complexity of binary droplet collisions increases for the collision of immiscible liquids with the occurrence of triple lines and thin encapsulating films. The Volume of Fluid (VOF) method is extended with an efficient interface reconstruction applicable to three-component cells of arbitrary configuration. Together with an enhanced Continuous S...
Conference Paper
The Collaborative Research Center (CRC) SFB-TRR 75 was established in January 2010 to focus on the dynamicsof basic drop processes, and in particular on processes involving extreme boundary conditions, for example, near thermodynamic critical conditions, very low temperatures, under strong electric fields or in situations involving extremely large...
Article
Ice formation in metastable, super-cooled droplets, which are frequently found in the atmosphere, influences the appearance and characteristics of atmospheric clouds significantly, for example regarding precipitation. Its numerical investigation can provide deep insight into the underlying physical mechanisms and supports the deduction of models th...
Article
In single-phase flow visualization, research focuses on the analysis of vector field properties. In two-phase flow, in contrast, analysis of the phase components is typically of major interest. So far, visualization research of two-phase flow concentrated on proper interface reconstruction and the analysis thereof. In this paper, we present a novel...
Article
The beginning of the ice-growth from a nucleus in the freezing process of a single supercooled droplet is modelled through a two-phase Stefan problem which is characterized by an unknown boundary separating the two distinct phases. A semi-analytical solution for the ice–water interface is presented using a perturbation method followed by an iterati...
Article
A brief overview of the main features of the code Free Surface 3D (FS3D) is presented here. FS3D is a Direct Numerical Simulation (DNS) code based on a Volume of Fluid (VOF) method to solve the incompressible Navier–Stokes equations. The energy equation is included and multiphase flows can be considered, in the sense that evaporation and ice growth...
Article
Two relevant computational models, one relying on a Level-Set approach, the other one on a Volume-of-Fluid tracking procedure with piecewise linear interface reconstruction, are comparatively assessed in terms of their capability to simulate crystallization of supercooled water. The models are preliminary validated by computing a one-dimensional fr...
Conference Paper
Piecewise linear interface calculation (PLIC) is one of the most widely employed reconstruction schemes for the simulation of multiphase flow. In this visualization paper we focus on the reconstruction from the simulation point of view, i.e., we present a framework for the analysis of this reconstruction scheme together with its implications on the...
Article
Full-text available
Homogeneous ice nucleation in supercooled water is studied with the classical nucleation theory (CNT). The nucleated ice particles are assumed to possess physical properties of metastable cubic ice. The comparison with literature data on homogeneous ice nucleation rates shows a good agreement between CNT predictions and experimental nucleation rate...
Article
The effect of axial heat conduction on the heat transfer is of importance if the flow Peclet number is small or if the axial extension of the heating zone is small. This paper therefore presents an analytical solution to the extended Graetz problem in a concentric annulus with piecewise constant temperature at the outer wall. The solution is based...
Conference Paper
Full-text available
An approach for simulating flows with more than two phases with the Volume of Fluid (VOF) based code Free Surface 3D (FS3D) is presented. The extension to the treatment of three different immiscible phases is done by implementing a second VOF variable and adapting the interface reconstruction. Introduction The in-house code Free Surface 3D (FS3D) i...
Conference Paper
A new method was implemented to simulate rigid body motion in the Volume of Fluid (VOF) based code Free Surface 3D (FS3D). The specific feature is that the method completely works within an Eulerian framework without the need for a Lagrangian representation of the rigid zone. It is shown that the technique is able to predict terminal velocities of r...

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