Magnetohydrodynamic Taylor-Couette flow at periodic and Hartmann wall conditions. - In: Magnetohydrodynamics, ISSN 0024-998X, Bd. 53 (2017), 1, S. 159-168
A study of turbulent Taylor-Couette flow between two cylinders in the presence of a uniform axial magnetic field is presented. The flow is driven by the rotating inner cylinder, and the outer cylinder is set to be fixed. Applying fully-3D numerical simulations in the approximation of low magnetic Reynolds number, the influence of the magnetic field on the turbulence intensity and structure is investigated with a variation of the Hartmann number. In the first part, periodic boundary conditions in the axial direction are taken into account that means no Hartmann layer formation. However, due to the high aspect ratio, the flow behavior can present a simplified version close to the real flow. In the second part, this study is compared with a study, where the Hartmann end-walls perpendicular to the magnetic field are introduced so that the flow is confined by the bottom and upper boundaries. In particular, the effects of the Hartmann walls and periodic condition on the process of generation and dissipation of turbulence under the magnetic field influence are compared.
Evolution of a round jet in a duct in the presence of a uniform axial magnetic field. - In: Magnetohydrodynamics, ISSN 0024-998X, Bd. 53 (2017), 1, S. 119-127
The spatially evolving flow of a liquid-metal jet in a duct with a streamwise uniform magnetic field is studied by direct numerical simulation. In contrast to the case of imposed transverse field, only the turbulent fluctuations of the flow are affected in this setup. They tend to form structures elongated along the applied magnetic field. In that case, turbulence becomes strongly anisotropic and, therefore, may completely change its properties. One interesting and important effect is the flow stabilization due to the magnetic field, whereby transition to turbulence can be delayed significantly. This occurs in the presence of moderate magnetic fields.
LACIS-T - a humid wind tunnel for investigating the interactions between cloud microphysics and turbulence. - In: Geophysical research abstracts, ISSN 1607-7962, Bd. 19 (2017), EGU2017-6475, insges. 1 S.
http://nbn-resolving.de/urn:nbn:de:gbv:ilm1-2017200561
Numerical studies of turbulent convection in liquid mercury and sodium. - In: DPG-Frühjahrstagung (DPG Spring Meeting) of the Condensed Matter Section (SKM), (2017), DY 16.5
Horizontal velocity fields in square large aspect ratio turbulent convection cells: comparison between experiment and simulation. - In: DPG-Frühjahrstagung (DPG Spring Meeting) of the Condensed Matter Section (SKM), (2017), DY 16.10
Revelation of interfacial energetics in organic multiheterojunctions. - In: Advanced science, ISSN 2198-3844, Bd. 4 (2017), 4, 1600331, S. 1-10
https://doi.org/10.1002/advs.201600331
Interfacial energetics in organic multi-heterojunctions by charge-transfer emission. - In: DPG-Frühjahrstagung (DPG Spring Meeting) of the Condensed Matter Section (SKM), (2017), CPP 70.6
Auch enthalten in: HL 88.6
Droplet dynamics and fine-scale structure in a shearless turbulent mixing layer with phase changes. - In: Journal of fluid mechanics, ISSN 1469-7645, Bd. 814 (2017), S. 452-483
Three-dimensional direct numerical simulations of a shearless mixing layer in a small fraction of the cloud-clear air interface are performed to study the response of an ensemble of cloud water droplets to the turbulent entrainment of clear air into a cloud filament. The main goal of this work is to understand how mixing of cloudy and clear air evolves as turbulence and thermodynamics interact through phase changes, and how the cloud droplets respond. In the main simulation case, mixing proceeds between a higher level of turbulence in the cloudy filament and a lower level of turbulence in the clear air environment - the typical shearless mixing layer set-up. Fluid turbulence is driven solely by buoyancy, which incorporates feedbacks from the temperature, the vapour content and the liquid water content fields. Two different variations on the core set of shearless mixing layer simulations are discussed, a simulation in a larger domain and a simulation with the same turbulence level inside the filament and its environment. Overall, it is found that, as evaporation occurs for the droplets that enter subsaturated clear air regions, buoyancy comes to dominate the subsequent evolution of the mixing layer. The buoyancy feedback leads initially to downdraughts at the cloudy-clear air interface and to updraughts in the bulk regions. The strength of the turbulence after initial transients depends on the domain size, showing that the range of scales is an important parameter in the shearless mixing layer set-up. In contrast, the level of turbulence in the clear air is found to have little effect on the evolution of the mixing process. The distributions of cloud water droplet size, supersaturation at the droplet positions and vertical velocity are more sensitive to domain size than to the details of the turbulence profile, suggesting that the evolution of cloud microphysics is more sensitive to large-scale as opposed to small-scale properties of the flow.
https://doi.org/10.1017/jfm.2017.23
Numerical simulations in low-Prandtl number convection. - In: Advances in computation, modeling and control of transitional and turbulent flows, (2016), S. 242-250
Velocity field in rectangular large-aspect-ratio turbulent convection cells: comparison between experiment and simulation :
Turbulente Geschwindigkeitsfelder in einer rechteckigen Konvektionszelle mit großem Aspektverhältnis: Vergleich zwischen Experiment und Simulation. - In: Experimentelle Strömungsmechanik, (2016), Seite 38-1-38-11