@inproceedings{BabcsanLeitlmeierMeieretal., author = {Babcsan, N. and Leitlmeier, D. and Meier, M. and Banhart, J. and Garcia-Moreno, F.}, title = {Measurements on cell walls and Plateau borders of particle stabilized foams}, series = {A collection of papers presented at the 5th European Conference on Foams, Emulsions, and Applications, EUFOAM 2004}, booktitle = {A collection of papers presented at the 5th European Conference on Foams, Emulsions, and Applications, EUFOAM 2004}, editor = {Vignes-Adler, Mich{\`e}le}, publisher = {Elsevier}, address = {Amsterdam [u.a.]}, language = {en} } @misc{ButtJehringEgbers, author = {Butt, Usman and Jehring, Lothar and Egbers, Christoph}, title = {Mechanism of drag reduction for circular cylinders with patterned surface}, series = {International journal of heat and fluid flow}, volume = {Vol. 45}, journal = {International journal of heat and fluid flow}, issn = {1879-2278}, pages = {128 -- 134}, language = {en} } @misc{UhligPreussGrafetal., author = {Uhlig, Benedict and Preuß, Ann-Christin and Graf, Johann and Neben, Matthias}, title = {Messtechnische und simulative Untersuchung des {\"O}lhaushalts an der Kolbengruppe}, series = {MTZ - Motortechnische Zeitschrift}, volume = {78}, journal = {MTZ - Motortechnische Zeitschrift}, number = {2}, issn = {2192-8843}, doi = {10.1007/s35146-016-0175-4}, pages = {76 -- 81}, abstract = {Die Projektreihe Kolbenring-{\"O}ltransport dient der Untersuchung der tribologischen Zust{\"a}nde in der Kolbengruppe. Dabei wurde im ersten Projektabschnitt ein 0,5-l-Einzylinder-Forschungsmotor aufgebaut, der mit zahlreichen Sensoren ausger{\"u}stet ist, um diese Zust{\"a}nde messtechnisch zu erfassen. Im zweiten, hier ausschnittsweise vorgestellten Projektabschnitt wurden zus{\"a}tzliche Simulationsmodelle implementiert, die durch Abgleich mit den aufgezeichneten Messdaten an Genauigkeit gewinnen und zum Verst{\"a}ndnis des {\"O}lhaushalts in der Kolbengruppe erheblich beitragen.}, language = {de} } @misc{MeierMeyerMutabazietal., author = {Meier, Martin and Meyer, Antoine and Mutabazi, Innocent and Egbers, Christoph}, title = {Microgravity experiments on thermo-electric flows}, series = {26th European Low Gravity Research Association Biennial Symposium and General Assembly, Granada (Spanien), September 24-27, 2019}, journal = {26th European Low Gravity Research Association Biennial Symposium and General Assembly, Granada (Spanien), September 24-27, 2019}, pages = {293 -- 294}, language = {en} } @article{FuttererGellertHuschtoetal., author = {Futterer, Birgit and Gellert, Marcus and Huschto, Michael and Larcher, Thomas von and Egbers, Christoph}, title = {Microgravity Science on International Space Station (ISS): The Geoflow Experiment}, language = {en} } @inproceedings{Futterer, author = {Futterer, Birgit}, title = {Minimierung von Diskretisierungsfehlern bei gitterunabh{\"a}ngiger Elektrodenpositionierung}, series = {62. Jahrestagung der Deutschen Geophysikalischen Gesellschaft im Jahr der Geowissenschaften}, booktitle = {62. Jahrestagung der Deutschen Geophysikalischen Gesellschaft im Jahr der Geowissenschaften}, publisher = {Deutsche Geophysikalische Gesellschaft}, address = {Hannover}, language = {de} } @misc{KupkaZaussingerMontgomery, author = {Kupka, Friedrich and Zaussinger, Florian and Montgomery, M. H.}, title = {Mixing and overshooting in surface convection zones of DA white dwarfs: First results from ANTARES}, series = {Monthly Notices of the Royal Astronomical Society}, volume = {474}, journal = {Monthly Notices of the Royal Astronomical Society}, number = {4}, issn = {1365-2966}, pages = {4660 -- 4671}, language = {en} } @phdthesis{Haun, author = {Haun, Peter}, title = {Modelling of thermo-electro hydrodynamic (TEHD) convection}, edition = {1st edition}, publisher = {Cuvillier Verlag}, address = {G{\"o}ttingen}, isbn = {978-3-689-52666-5}, doi = {10.61061/ISBN_9783689526665}, pages = {XXIV, 369}, abstract = {In Thermo-Electro Hydrodynamics (TEHD), an electric field is applied to a fluid within a heated domain to induce thermal convection. The fluid and the electric field must meet specific conditions to establish a dielectrophoretic force that acts as a buoyancy force on the fluid. This buoyancy force is utilised in experiments to replicate gravitational buoyancy, explore resulting flow structures, or develop heat transfer systems without moving parts. In this study, the electric force field acting on a dielectric fluid in a capacitor is derived from the Maxwell equations and coupled with the Navier-Stokes equation for fluid motion. Furthermore, an Open Source Field Operation and Manipulation (OpenFOAM) solver is extended to incorporate TEHD momentum and energy-contributing terms. In a dimensional analysis, dimensionless parameters are derived and tested. Therefore, parameter studies in 2D approximations of planar and cylindrical geometries are done. Additionally, the 2D investigations are utilised to study the behaviour of heat transfer and boundary layer properties, and some scaling laws are derived. Finally, 3D spherical shell microgravity experiments are analysed and linked to the results of 3D numerical analysis. The results verify the derived methods, which are expanded and applied to the upcoming space experiment, AtmoFlow.}, language = {en} } @misc{GaillardSzaboTravnikovetal., author = {Gaillard, Yann and Szabo, Peter and Travnikov, Vadim and Egbers, Christoph}, title = {Modelling Thermo-Electrohydrodynamic Convection in Rotating Spherical Shell Using OpenFOAM ®}, series = {OpenFOAM® Journal}, volume = {5 (2025)}, journal = {OpenFOAM® Journal}, doi = {10.51560/ofj.v5.136}, pages = {1 -- 16}, language = {en} } @incollection{ZanounEgbersJehring, author = {Zanoun, El-Sayed and Egbers, Christoph and Jehring, Lothar}, title = {Modified Optical and Thermal Anemometers for Laminar and Turbulent Boundary Layers Investigation}, language = {en} } @inproceedings{FroitzheimMerboldEgbers, author = {Froitzheim, Andreas and Merbold, Sebastian and Egbers, Christoph}, title = {Momentum transport and flow structures in a wide gap fully turbulent Taylor-Couette flow}, series = {Book of abstracts, 11th European Fluid Mechanics Conference (EFMC), 12-16 September, Seville, Spain}, booktitle = {Book of abstracts, 11th European Fluid Mechanics Conference (EFMC), 12-16 September, Seville, Spain}, pages = {1}, language = {en} } @misc{ZanounDurst, author = {Zanoun, El-Sayed and Durst, F.}, title = {Momentum transport and turbulent kinetic energy production in plane-channel flow}, language = {en} } @inproceedings{LarcherHarlanderSeeligetal., author = {Larcher, Thomas von and Harlander, Uwe and Seelig, Torsten and Randriamampianina, Anthony and Viazzo, Stephane and Vincze, Miklos}, title = {Multiple scales in the thermally driven rotating annulus: time-series data analysis of experiments and numerics}, series = {ICTW 19, Book of Abstracts, 19th International Couette-Taylor Workshop, June 24 - 26, 2015 Cottbus, Germany}, booktitle = {ICTW 19, Book of Abstracts, 19th International Couette-Taylor Workshop, June 24 - 26, 2015 Cottbus, Germany}, address = {Cottbus}, pages = {40 -- 41}, language = {en} } @misc{SchaffrathStathopoulosSchmitzetal., author = {Schaffrath, Robert and Stathopoulos, Panagiotis and Schmitz, Andreas and Nicke, Eberhard}, title = {Multistage turbomachinery optimization for high-temperature heat pumps with the reverse rankine cycle}, series = {Journal of turbomachinery}, volume = {147}, journal = {Journal of turbomachinery}, number = {111003}, publisher = {ASME}, address = {New York, NY}, issn = {1528-8900}, doi = {10.1115/1.4068480}, pages = {111003-1 -- 111003-12}, abstract = {The electrification of process heat generation will be a key to achieving carbon neutrality in the coming decades. One of the most promising approaches is to replace conventional heat supply systems with high-temperature heat pumps (HTHPs). A promising heat pump concept is based on the reverse Rankine cycle that uses water as its working fluid. By using turbomachinery for the compression process in this cycle, the performance of the HTHP can be increased compared to the volumetric displacement systems, like screw or piston compressors. Although the design of the compressor geometry can be done sequentially in relation to the HTHP cycle design, better results can be obtained by an approach that integrates turbomachinery and the thermodynamic cycle design. Against this background, an automated optimization method for a reverse Rankine HTHP with two radial turbo-compressors in series is presented. In contrast to the current state of the art, the presented novel optimization approach uses 3D computational fluid dynamics data to calculate the compressor's performance. Furthermore, the integration of low-fidelity compressor specific reduced-order models are used to accelerate the gradient-free optimization process by a CO-Kriging surrogate model. The advantages of the novel approach are justified by comparing the numerical effort and the final values of the optimization objectives.}, language = {en} } @misc{LarcherHarlanderAlexandrovetal., author = {Larcher, Thomas von and Harlander, Uwe and Alexandrov, Kiril and Wang, Yongtai}, title = {Multivariate statistical data analysis methods for detecting baroclinic wave interactions in the thermally driven rotating annulus}, language = {en} } @inproceedings{LarcherHarlanderEgbers, author = {Larcher, Thomas von and Harlander, Uwe and Egbers, Christoph}, title = {Multivariate statistical data analysis methods for detecting baroclinic wave interactions in the thermally driven rotating annulus}, language = {en} } @incollection{TravnikovHollerbachEgbers, author = {Travnikov, Vadim and Hollerbach, Rainer and Egbers, Christoph}, title = {Natural Convection in rotating Spherical gap under the central Force Field}, language = {en} } @article{FuttererBrucksHollerbachetal., author = {Futterer, Birgit and Brucks, A. and Hollerbach, Rainer and Egbers, Christoph}, title = {Natural convection in sperical shells: dripping vortex flow for high Prandtl number fluids}, language = {en} } @inproceedings{JehringZanounEgbers, author = {Jehring, Lothar and Zanoun, El-Sayed and Egbers, Christoph}, title = {Near-wall flow measurements by means of miniaturized LDV flow sensor combined with hot-film anemometry}, language = {en} } @incollection{AugensteinEgbersEckert, author = {Augenstein, Edgar and Egbers, Christoph and Eckert, S.}, title = {Neues Sensorkonzept zur Bestimmung der aerodynamischen Wand-Schubspannung}, language = {de} } @inproceedings{ZanounEgbersJehring, author = {Zanoun, El-Sayed and Egbers, Christoph and Jehring, Lothar}, title = {New Approach for Wall Shear Stress Measurements}, language = {en} } @misc{HarlanderSukhanovskiiAbideetal., author = {Harlander, Uwe and Sukhanovskii, Andrei and Abide, St{\´e}phane and Borcia, Ion-Dan and Popova, Elene and Rodda, Costanza and Vasiliev, Andrei and Vincze, Miklos}, title = {New Laboratory Experiments to Study the Large-Scale Circulation and Climate Dynamics}, series = {Atmosphere}, volume = {14}, journal = {Atmosphere}, number = {5}, doi = {10.3390/atmos14050836}, pages = {19}, abstract = {The large-scale flows of the oceans and the atmosphere are driven by a non-uniform surface heating over latitude, and rotation. For many years scientists try to understand these flows by doing laboratory experiments. In the present paper we discuss two rather new laboratory experiments designed to study certain aspects of the atmospheric circulation. One of the experiments, the differentially heated rotating annulus at the Brandenburg University of Technology (BTU) Cottbus, has a cooled inner cylinder and a heated outer wall. However, the structure of the atmospheric meridional circulation motivates a variation of this "classical" design. In the second experiment described, operational at the Institute of Continuous Media Mechanics (ICMM) in Perm, heating and cooling is performed at different vertical levels that resembles more the atmospheric situation. Recent results of both experiments are presented and discussed. Differences and consistencies are highlighted. Though many issues are still open we conclude that both setups have their merits. The variation with heating and cooling at different levels might be more suited to study processes in the transition zone between pure rotating convection and the zone of westerly winds. On the other hand, the simpler boundary conditions of the BTU experiment make this experiment easier to control.}, language = {en} } @inproceedings{ZaussingerEgbersKrebsetal., author = {Zaussinger, Florian and Egbers, Christoph and Krebs, Andreas and Travnikov, Vadim}, title = {New results of the spherical convection experiment Geoflow IIc}, series = {European Geosciences Union General Assembly 2017 Vienna, Austria, 23-28 April 2017}, booktitle = {European Geosciences Union General Assembly 2017 Vienna, Austria, 23-28 April 2017}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, language = {en} } @article{HollerbachJunkEgbers, author = {Hollerbach, Rainer and Junk, M. and Egbers, Christoph}, title = {Non-axisymmetric instabilities in basic state spherical Couette flow}, language = {en} } @inproceedings{FuttererZaussingerKrebsetal., author = {Futterer, Birgit and Zaussinger, Florian and Krebs, Andreas and Egbers, Christoph}, title = {Non-linear effects and associated instabilities in spherical Rayleigh-Benard experiments with variation of the viscosity contrast}, language = {en} } @inproceedings{FuttererLarcherEgbers, author = {Futterer, Birgit and Larcher, Thomas von and Egbers, Christoph}, title = {Non-rotational and rotational regimes of spherical gap flows and their influence on thermal convection in a set-up with central force field}, language = {en} } @inproceedings{FuttererZaussingerKochetal., author = {Futterer, Birgit and Zaussinger, Florian and Koch, Sandy and Krebs, Andreas and Egbers, Christoph}, title = {Nonlinear effects and associated instabilities in iso-viscous and temperature-dependent viscous thermal convection in spherical shells, the geophysical flow simulation experiment integrated in Fluid Science Laboratory}, language = {en} } @article{Meier, author = {Meier, M.}, title = {Nonmetallic solid foams - a non-exhaustive overview}, language = {en} } @misc{HarlanderBorciaKrebs, author = {Harlander, Uwe and Borcia, Ion-Dan and Krebs, Andreas}, title = {Nonnormality increases variance of gravity waves trapped in a tilted box}, series = {Geophysical \& Astrophysical Fluid Dynamics}, volume = {113}, journal = {Geophysical \& Astrophysical Fluid Dynamics}, number = {5/6}, issn = {1029-041}, doi = {10.1080/03091929.2018.1549660}, pages = {602 -- 622}, language = {en} } @inproceedings{RoddaBorciaHienetal., author = {Rodda, Costanza and Borcia, Ion-Dan and Hien, Steffen and Achatz, Ulrich and Le Gal, Patrice and Harlander, Uwe}, title = {Numerical and experimental study of inertia-gravity waves in the differentially heated rotating annulus}, series = {European Geosciences Union, General Assembly 2018, Vienna, Austria, 8-13 April 2018}, booktitle = {European Geosciences Union, General Assembly 2018, Vienna, Austria, 8-13 April 2018}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, language = {en} } @article{ScurtuStueckeEgbers, author = {Scurtu, Nicoleta and St{\"u}cke, Peter and Egbers, Christoph}, title = {Numerical and experimental study of the flow in an eccentric Couette - Taylor system with small gap}, language = {en} } @article{ScurtuBaensch, author = {Scurtu, Nicoleta and B{\"a}nsch, E.}, title = {Numerical and Stability Aspects of Non-Newtonain Fluid Flow}, language = {en} } @inproceedings{ScurtuEgbers, author = {Scurtu, Nicoleta and Egbers, Christoph}, title = {Numerical determination of the particle separation efficiency of industrial filters}, language = {en} } @inproceedings{JunkHollerbachEgbers, author = {Junk, M. and Hollerbach, Rainer and Egbers, Christoph}, title = {Numerical investigation of the flow in wide spherical gaps}, language = {en} } @misc{AbuKhassCristofaroKopparthyetal., author = {Abu Khass, Omar and Cristofaro, Marco and Kopparthy, Saketh Bharadwaj and Kl{\"o}ppel, Steffen and Nicke, Eberhard and Stathopoulos, Panagiotis}, title = {Numerical investigation of two-phase water ejectors for high-temperature heat pumps : insights into flow behavior and shock wave dynamics}, series = {Proceedings of ASME Turbo Expo 2025 : Turbomachinery Technical Conference and Exposition, June 16-20, 2025, Memphis, Tennessee : Volume 4 : Controls, Diagnostics \& Instrumentation; Cycle Innovations; Education; Electric Power}, journal = {Proceedings of ASME Turbo Expo 2025 : Turbomachinery Technical Conference and Exposition, June 16-20, 2025, Memphis, Tennessee : Volume 4 : Controls, Diagnostics \& Instrumentation; Cycle Innovations; Education; Electric Power}, publisher = {American Society of Mechanical Engineers}, address = {New York, NY}, isbn = {978-0-7918-8880-3}, doi = {10.1115/GT2025-151706}, pages = {11}, abstract = {Two-phase water ejectors can serve as a secondary steam compression mechanism in high-temperature heat pump (HTHP) systems. By integrating an ejector, high-pressure water can be combined with hot steam from the compressor, achieving simultaneous cooling and pressure increase. This integration offers the potential to reduce both the power and the number of stages required to obtain the specified compression. However, the complex flow behavior within two-phase water ejectors, especially under high-pressure, high-temperature conditions, remains insufficiently explored in the literature. This study addresses this gap by conducting a detailed numerical investigation of two-phase flow and shock wave behavior using the compressible two-phase mixture approach in computational fluid dynamics (CFD) commercial solver Ansys Fluent. The ejector geometry and critical operating points were derived from a prior study using one-dimensional (1D) analysis, which provided the design and operational conditions used in the current simulations. The ejector was modeled in two-dimensional (2D) axisymmetric configurations. The Lee model, in conjunction with the water saturation curve, was applied to capture non-equilibrium mass transfer processes, including evaporation and condensation. During the simulations, the presence of a liquid-vapor mixture may cause the speed of sound to drop, making the flow locally supersonic. Initial simulations revealed a series of shock waves in the mixing section, which elevated the mixture flow pressure to the designated set back-pressure value, thereby achieving an ejector pressure ratio of approximately 1.3. These findings provide crucial insights into how thermodynamic conditions influence two-phase flow behavior, particularly in the generation and intensity of shock waves. This work advances the modeling procedures for two-phase ejectors and enhances the understanding of the physical phenomena occurring within two-phase water ejectors designed for HTHP applications.}, language = {en} } @misc{HerzogEgbers, author = {Herzog, Nicoleta and Egbers, Christoph}, title = {Numerical prediction of pressure drop and particle separation efficiency of some vane-type dust filters}, series = {Powder Technology}, volume = {245}, journal = {Powder Technology}, issn = {0032-5910}, doi = {10.1016/j.powtec.2013.04.050}, pages = {265 -- 272}, language = {en} } @misc{ZaussingerKupkaMontgomeryetal., author = {Zaussinger, Florian and Kupka, Friedrich and Montgomery, M. and Egbers, Christoph}, title = {Numerical simulation of DA white dwarf surface convection}, series = {Journal of physics / Conference Series}, volume = {1031}, journal = {Journal of physics / Conference Series}, number = {1}, issn = {1742-6596}, doi = {10.1088/1742-6596/1031/1/012013}, pages = {7}, language = {en} } @inproceedings{BraschSitteEgbers, author = {Brasch, W. and Sitte, B. and Egbers, Christoph}, title = {Numerical simulation of thermal convection in spherical shellsPreparation of Space experiments}, language = {en} } @inproceedings{FuttererGellertTravnikov, author = {Futterer, Birgit and Gellert, Marcus and Travnikov, Vadim}, title = {Numerical Studies for GeoFlow: Dynamics of Thermal Convection in Rotating Spherical Shells}, language = {en} } @article{StueckeScurtuEgbers, author = {St{\"u}cke, Peter and Scurtu, Nicoleta and Egbers, Christoph}, title = {Numerische Untersuchung der Sr{\"o}mung in Gleitlagern}, language = {de} } @phdthesis{Junk, author = {Junk, Markus}, title = {Numerische Untersuchung der Stabilit{\"a}t der Str{\"o}mung im weiten Kugelspalt}, publisher = {Cuvillier Verlag}, address = {G{\"o}ttngen}, isbn = {3-86537-345-3}, language = {de} } @article{BraschSitteEgbers, author = {Brasch, W. and Sitte, B. and Egbers, Christoph}, title = {Numerische Untersuchung der thermischen Konvektion in einer weiten Kugelschale}, language = {de} } @inproceedings{Egbers, author = {Egbers, Christoph}, title = {Observation of Nanoparticle Aggregation in a tube flow under microgravity conditions}, series = {34th COSPAR Scientific Assembly, The Second World Space Congress, held 10-19 October, 2002 in Houston, TX, USA., meeting abstract}, booktitle = {34th COSPAR Scientific Assembly, The Second World Space Congress, held 10-19 October, 2002 in Houston, TX, USA., meeting abstract}, language = {en} } @inproceedings{ZanounKoenigAlMutairietal., author = {Zanoun, El-Sayed and K{\"o}nig, Franziska and Al-Mutairi, Fahad M. and Egbers, Christoph and {\"O}ng{\"u}ner, Emir}, title = {On the Application of Hot Wires and Pitot Tubes in Pipe and Channel Flows}, series = {HEFAT 2014, 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, 6 - 9 July 2014 Orlando, Florida}, booktitle = {HEFAT 2014, 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, 6 - 9 July 2014 Orlando, Florida}, doi = {10.13140/2.1.3766.7521}, pages = {7}, language = {en} } @misc{KoenigZanounJehringetal., author = {K{\"o}nig, Franziska and Zanoun, El-Sayed and Jehring, Lothar and Egbers, Christoph}, title = {On the behavior of the inner peak in turbulent pipe flow}, language = {en} } @misc{MelettiAbideHarlanderetal., author = {Meletti, Gabriel and Abide, St{\´e}phane and Harlander, Uwe and Raspo, Isabelle and St{\´e}phane Viazzo, St{\´e}phane}, title = {On the influence of the heat transfer at the free surface of a thermally driven rotating annulus}, series = {Physics of fluids}, volume = {37}, journal = {Physics of fluids}, publisher = {AIP Publishing}, address = {College Park, MD}, issn = {1089-7666}, doi = {10.1063/5.0248712}, pages = {1 -- 16}, abstract = {Experiments on rotating annuli that are differentially heated in the radial direction have largely contributed to a better understanding of baroclinic instabilities. This configuration creates waves at a laboratory scale that are related to atmospheric circulations. Pioneer studies in baroclinic tanks have shown that experiments with low aspect ratios are more suitable to reproduce small-scale inertia gravity waves, but these tanks have a larger free surface, which leads to higher interactions with their surrounding environment. Considering the heat transferred through the free surface, the present work investigates its impacts on the baroclinic instability using direct numerical simulations (DNS).}, language = {en} } @inproceedings{BonczekEgbers, author = {Bonczek, P. and Egbers, Christoph}, title = {On the influence of thermal convection in classical Taylor-Couette flows}, language = {en} } @inproceedings{MalteseMelettideOliveiraRaspoSeeligetal., author = {Maltese Meletti de Oliveira, Gabriel and Raspo, Isabelle and Seelig, Torsten and Viazzo, Stephane and Randriamampianina, Anthony and Abide, St{\´e}phane and Krebs, Andreas and Harlander, Uwe}, title = {On the instability of radially sheared and axially stratified vortex flow}, series = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, booktitle = {European Geosciences Union, General Assembly 2018, Vienna, Austria}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, language = {en} } @inproceedings{LarcherFuttererEgbers, author = {Larcher, Thomas von and Futterer, Birgit and Egbers, Christoph}, title = {On the status of experimental preparation of spherical gap flow experiments with central force field on International Space Station (ISS)}, language = {en} } @inproceedings{ZanounOenguenerEgbersetal., author = {Zanoun, El-Sayed and {\"O}ng{\"u}ner, Emir and Egbers, Christoph and Bellani, Gabriele and Talamelli, Alessandro}, title = {One-Dimensional Flow Spectra and Cumulative Energy from Two Pipe Facilities}, series = {iTi 2018 Conference on Turbulence VIII, September 5-7, 2018, Bertinoro, Italy, Book of abstract}, booktitle = {iTi 2018 Conference on Turbulence VIII, September 5-7, 2018, Bertinoro, Italy, Book of abstract}, pages = {S. 100}, language = {en} } @inproceedings{SeeligJongmannsMeyeretal., author = {Seelig, Torsten and Jongmanns, Marcel and Meyer, Antoine and Meier, Martin and Egbers, Christoph}, title = {Onset of dielectrophoretic force-driven convection in annular geometry under Earth's gravity}, series = {20th International Couette-Taylor Workshop, 11-13 July 2018, Marseille, France, Book of abstracts}, booktitle = {20th International Couette-Taylor Workshop, 11-13 July 2018, Marseille, France, Book of abstracts}, pages = {2}, language = {en} } @article{BrucksSitteEgbers, author = {Brucks, A. and Sitte, B. and Egbers, Christoph}, title = {Onset of thermal convection and influence of rotation in wide spherical gaps}, language = {en} } @inproceedings{MerboldBrauckmannEgbers, author = {Merbold, Sebastian and Brauckmann, Hannes and Egbers, Christoph}, title = {Optimal angular momentum flux of wide gap Taylor-Couette flow}, series = {Book of abstracts, 9th European Fluid Mechanics Conference (EFMC), 9-13 September, Rome, Italy}, booktitle = {Book of abstracts, 9th European Fluid Mechanics Conference (EFMC), 9-13 September, Rome, Italy}, language = {en} } @incollection{HarlanderLarcherWrightetal., author = {Harlander, Uwe and Larcher, Thomas von and Wright, G. B. and Hoff, Michael and Alexandrov, Kiril and Egbers, Christoph}, title = {Orthogonal decomposition methods to analyze PIV, LDV and thermography data of a thermally driven rotating annulus laboratory experiment}, series = {Modeling Atmospheric and Oceanic Flows: Insights from Laboratory Experiments and Numerical Simulations}, booktitle = {Modeling Atmospheric and Oceanic Flows: Insights from Laboratory Experiments and Numerical Simulations}, editor = {Larcher, Thomas von and Williams, Paul D.}, publisher = {Wiley}, address = {Hoboken}, isbn = {978-1-118-85593-5}, doi = {10.1002/9781118856024}, pages = {315 -- 336}, language = {en} } @misc{DahleyFuttererEgbersetal., author = {Dahley, Norman and Futterer, Birgit and Egbers, Christoph and Crumeyrolle, Olivier and Mutabazi, Innocent}, title = {Parabolic flight experiment "Convection in a Cylinder" : Convection patterns in varying buoyancy forces}, series = {Journal of Physics: Conference Series}, volume = {318}, journal = {Journal of Physics: Conference Series}, issn = {1742-6588}, doi = {10.1088/1742-6596/318/8/082003}, pages = {082003}, language = {en} } @phdthesis{Shen, author = {Shen, Jianqi}, title = {Particle Size Analysis by Transmission Fluctuation Spectrometry: Fundamentals and Case Studies}, publisher = {Cuvillier Verlag}, address = {G{\"o}ttingen}, isbn = {3-89873-946-5}, language = {en} } @incollection{DetersGliemannEgbers, author = {Deters, T. and Gliemann, S. and Egbers, Christoph}, title = {Particle-Image-Velocimetry unter Einsatz von thermochromen Fl{\"u}ssigkristallen}, language = {en} } @inproceedings{RistauMeierEgbersetal., author = {Ristau, R. and Meier, M. and Egbers, Christoph and Schmidt, J.-R. and Poppe, T.}, title = {Partikelbeladene Str{\"o}mungen : Simulation und Messtechnik}, language = {de} } @article{FuttererHollerbachEgbers, author = {Futterer, Birgit and Hollerbach, Rainer and Egbers, Christoph}, title = {Periodical convective flow in spherical shells}, language = {en} } @misc{KuehneSliavinSzaboetal., author = {K{\"u}hne, Simon and Sliavin, Yaraslau and Szabo, Peter and Carter, Richard and Krebs, Andreas and Egbers, Christoph}, title = {Phase-demodulation of interferograms of thermo-electrohydrodynamic convection in a differentially heated cylindrical annulus}, series = {Experimentelle Str{\"o}mungsmechanik : 31. Fachtagung, 3.-5. September 2024, Berlin / Herausgeber: C. Rauh, B. Ruck, A. Leder}, journal = {Experimentelle Str{\"o}mungsmechanik : 31. Fachtagung, 3.-5. September 2024, Berlin / Herausgeber: C. Rauh, B. Ruck, A. Leder}, publisher = {German Association for Laser Anemometry 26.8 GALA e.V.}, address = {Karlsruhe}, isbn = {978-3-9816764-4-0}, pages = {7.1. -- 7.8}, language = {en} } @inproceedings{MerboldHarlanderEgbers, author = {Merbold, Sebastian and Harlander, Uwe and Egbers, Christoph}, title = {Physics of rotating fluids, a DFG core facility centre}, series = {88th Annual Meeting of the International Association of Applied Mathematics and Mechanics GAMM, March 6-10, 2017, Weimar, Germany, Book of abstracts}, booktitle = {88th Annual Meeting of the International Association of Applied Mathematics and Mechanics GAMM, March 6-10, 2017, Weimar, Germany, Book of abstracts}, pages = {S. 355}, language = {en} } @misc{RichterZanounPeixinhoetal., author = {Richter, Stefan and Zanoun, El-Sayed and Peixinho, Jorge and Egbers, Christoph}, title = {Pipe Flow Development and Transition in CoSmaPipe Facility}, series = {Proceedings in applied mathematics and mechanics : PAMM}, volume = {23}, journal = {Proceedings in applied mathematics and mechanics : PAMM}, number = {1}, issn = {1617-7061}, doi = {10.1002/pamm.202300001}, language = {en} } @misc{SzaboMeierMeyeretal., author = {Szabo, Peter and Meier, Martin and Meyer, Antoine and Barry, Elhadj and Motuz, Vasyl and Mutabazi, Innocent and Egbers, Christoph}, title = {PIV and shadowgraph measurements of thermo-electrohydrodynamic convection in a horizontal aligned differentially heated annulus at different gravity conditions}, series = {Experimental Thermal and Fluid Science}, volume = {129}, journal = {Experimental Thermal and Fluid Science}, issn = {1879-2286}, doi = {10.1016/j.expthermflusci.2021.110470}, language = {en} } @inproceedings{SeeligBurchardtKrebsetal., author = {Seelig, Torsten and Burchardt, Martin and Krebs, Andreas and Harlander, Uwe and Egbers, Christoph}, title = {PIV measurements in an axially stratified Taylor-Couette experiment}, series = {Book of abstracts, School ISTROF 2016, Instabilities and Turbulence in Strato-Rotational Flows, July 11-13th, 2016, Le Havre}, booktitle = {Book of abstracts, School ISTROF 2016, Instabilities and Turbulence in Strato-Rotational Flows, July 11-13th, 2016, Le Havre}, language = {en} } @inproceedings{SmieszekAbchaMutabazietal., author = {Smieszek, Marlene and Abcha, N. and Mutabazi, Innocent and Egbers, Christoph}, title = {PIV measurements in viscoelastic polyacrylamide solution in Taylor-Couette system}, language = {en} } @incollection{FroitzheimMerboldEgbers, author = {Froitzheim, Andreas and Merbold, Sebastian and Egbers, Christoph}, title = {PIV Messungen in einer Taylor-Couette Str{\"o}mung mit weitem Spalt}, series = {Lasermethoden in der Str{\"o}mungsmesstechnik, 23. Fachtagung, 8. - 10. September 2015, Dresden}, booktitle = {Lasermethoden in der Str{\"o}mungsmesstechnik, 23. Fachtagung, 8. - 10. September 2015, Dresden}, publisher = {GALA}, address = {Karlsruhe}, isbn = {978-3-9816764-1-9}, pages = {S. 27}, language = {de} } @misc{HarlanderLarcherWangetal., author = {Harlander, Uwe and Larcher, Thomas von and Wang, Yongtai and Egbers, Christoph}, title = {PIV- and LDV-measurements of baroclinic wave interactions in a thermally driven rotating annulus}, doi = {10.1007/s00348-009-0792-5}, language = {en} } @misc{HarlanderBorciaVinczeetal., author = {Harlander, Uwe and Borcia, Ion-Dan and Vincze, Miklos and Rodda, Costanza}, title = {Probability Distribution of Extreme Events in a Baroclinic Wave Laboratory Experiment}, series = {Fluids}, volume = {7}, journal = {Fluids}, number = {8}, issn = {2311-5521}, doi = {10.3390/fluids7080274}, abstract = {Atmospheric westerly jet streams are driven by temperature differences between low and high latitudes and the rotation of the Earth. Meandering jet streams and propagating Rossby waves are responsible for the variable weather in the mid-latitudes. Moreover, extreme weather events such as heat waves and cold spells are part of the jet stream dynamics. For many years, a simple analog in the form of a simplified laboratory experiment, the differentially heated rotating annulus, has provided insight into the dynamics of the meandering jet stream. In the present study, probability density distributions of extreme events from a long-term laboratory experiment are studied and compared to the atmospheric probability density distributions. Empirical distributions of extreme value monthly block data are derived for the experimental and atmospheric cases. Generalized extreme value distributions are adjusted to the empirical distributions, and the distribution parameters are compared. Good agreement was found, but the distributions of the experimental data showed a shift toward larger extreme values, and some explanations for this shift are suggested. The results indicate that the laboratory model might be a useful tool for investigating changes in extreme event distributions due to climate change. In the laboratory context, the change can be modeled by an increase in total temperature accompanied by a reduction in the radial heat contrast.}, language = {en} } @misc{BourasFellahBarilleetal., author = {Bouras, Dikra and Fellah, Mamoun and Barille, Regis and Obrosov, Aleksei and El-Hiti, Gamal A.}, title = {Production of novel Zr-Mg nanoceramics based on kaolinite clay with strong antibacterial activity}, series = {Ceramics International}, volume = {50}, journal = {Ceramics International}, number = {16}, publisher = {Elsevier}, issn = {1873-3956}, doi = {https://doi.org/10.1016/j.ceramint.2024.05.091}, pages = {27949 -- 27960}, abstract = {Gram-negative bacteria Pseudomonas putida, Gram-positive Bacillus subtilis, and Staphylococcus aureus were utilized as test samples to evaluate the antibacterial characteristics of DD3-clay/MgO and DD3+38 wt\% ZrO2-clay/MgO nanoparticles. The ceramic powders prepared by a thermal autoclave method are characterized before and after Mg addition by SEM, EDX, XRD, IR, UV-visible, and TEM in order to investigate microstructure, phase, and surface morphology. The results showed that after adding Mg, it led to the deformation of the crystal lattices of (mullite, zirconium silicate, and zirconium oxide) together with a decrease in particle size (75-103 nm) and a complete change in its shape from nanotube to nanospherical, as observed by SEM and TEM analyses. It also confirmed by UV-visible spectroscopy that the addition of Mg increases the absorbance accompanying a decrease in the energy gap of 1.91, 1.74, 1.73, and 1.43 eV corresponding to DD3, DD3Z, DD3/30 wt\% Mg and DD3Z/30 wt\% Mg respectively. The antibacterial mechanism is related to the size of the particles, the solvent used for powder dissolution, the nanoparticle's size when they come into touch with bacteria, and the generation of reactive oxygen species (ROS: ˙O2-, ˙OH, and H2O2). It was observed that the anti-bacterial activity is enhanced with 10 wt\% and 30 wt\% of Mg added to a modified ceramic powder. Also, more O2- is formed on the surface of the prepared powder, which penetrates the bacterial cell and destroys it. The nanocomposite particles showed remarkable antibacterial activity when they were dissolved in DMSO compared to methanol and chloroform as organic solvents. The aim is to enrich knowledge on the antibacterial activities of metal nanoparticles (ZrSiO4 and MgO) on three bacterial strains with different Grams due to their extensive involvement in the phenomena of contamination and infection encountered in the medical field. The synthesized nanoparticles have good antimicrobial activity against all strains tested. A maximum inhibition zone of 35 ± 0.2 mm was obtained with S. aureus, a zone of 23 ± 0.46 mm with P. putida and a zone of 27 ± 0.46 nm with B. subtilis for DD3/30 wt\% Mg and an inhibition zone of 38 ± 0.93 mm, 26 ± 0.24 nm and 17 ± 0.33 nm was obtained with same strains for DD3Z/30 wt\% Mg, respectively.}, language = {en} } @misc{ScurtuFuttererEgbers, author = {Scurtu, Nicoleta and Futterer, Birgit and Egbers, Christoph}, title = {Pulsating and traveling wave modes of natural convection in spherical shells}, language = {en} } @misc{PanahandehMayGrosseKockertetal., author = {Panahandeh, Sara and May, Daniel and Grosse-Kockert, Corina and Schacht, Ralph and Abo Ras, Mohamad and Wunderle, Bernhard}, title = {Pulsed infrared thermal imaging as inline quality assessment tool}, series = {Microelectronics Reliability}, volume = {2023}, journal = {Microelectronics Reliability}, number = {Volume 142}, issn = {0026-2714}, doi = {10.1016/j.microrel.2023.114910}, pages = {1 -- 11}, abstract = {Pulsed infrared thermography (PIRT) is a very fast and non-destructive technique for testing various types of specimens. This makes PIRT interesting for 100 \%-inspections in industrial production lines. Especially for the die attach interface inspection of sintered and soldered electronic components and layer-to-layer interfaces in fiber-reinforced plastic (FRP), the industry is looking for alternatives to cost intensive X-ray methods and the time-consuming scanning acoustic microscopy (C-SAM). A big challenge to use the PIRT technology for inspections in industrial production lines is the low emissivity of the surface of the device under test (DUT). This work will present a PIRT system including a vacuum foil lamination setup to avoid the necessary spray coating of DUTs with low emissivity surfaces in failure analyses. This system can be used as inline quality assessment tool with an integrated technique to perform reliable component inspections on a wide range of different specimens.}, language = {en} } @misc{KrieseLockanSchaffrathetal., author = {Kriese, Maximilian and Lockan, Michael and Schaffrath, Robert and Stathopoulos, Panagiotis}, title = {Quasi-static simulation of a start-up procedure for a multistage centrifugal compression system}, series = {Proceedings of ASME Turbo Expo 2025 : Turbomachinery Technical Conference and Exposition, June 16-20, 2025, Memphis, Tennessee : Volume 4 : Controls, Diagnostics \& Instrumentation; Cycle Innovations; Education; Electric Power}, journal = {Proceedings of ASME Turbo Expo 2025 : Turbomachinery Technical Conference and Exposition, June 16-20, 2025, Memphis, Tennessee : Volume 4 : Controls, Diagnostics \& Instrumentation; Cycle Innovations; Education; Electric Power}, publisher = {American Society of Mechanical Engineers}, address = {New York, NY}, isbn = {978-0-7918-8880-3}, doi = {10.1115/GT2025-151935}, pages = {12}, abstract = {In order to achieve the European Union's climate protection targets by 2050, energy use in the private and industrial sectors must be switched from using fossil fuels to renewable energy. For industry, this might require that the production processes itself needed to be changed or new technologies to manufacture in a sustainable way needed to be introduced. One example of the latter mentioned are high-temperature heat pumps (HTHP), which will be capable to generate sustainable process heat up to 300°C e.g. for the pulp and paper or food industry. There are currently only a few HTHPs commercially available that can reach temperatures above 150°C. In order to overcome the technological challenges to reach 300°C, two HTHP prototypes are currently developed at the Institute of Low-Carbon Industrial Processes of the German Aerospace Centre (DLR). One of them is the pilot plant ZiRa which is based on the reversed Rankine process and uses steam as its working medium. Herein three centrifugal compressors are applied to achieve a saturated steam temperature of 200°C at the sink. The safe speed-up of these three compressors, titled as the start-up procedure, from the standstill of each compressors up to their respective nominal speed, is modelled in the flow chart software EBSILON Professional. In addition to the compressors, all necessary components, i.e. the intercoolers, the fittings and valves, the pipes, the separators and the bypasses are modelled so that all parameters influencing the thermodynamic inlet state of the respective compressor are considered. The start-up of the multi-stage compression system of the pilot plan ZiRa is shown as a quasi-static time series. As a first step, the speed increments are defined. Afterwards, absolute pressures between 1.25 and 2 bar upstream of the first compressor and their effect on the operation of the subsequent compressor stages, are analyzed. Therefore, the mass flow rates and rotational speeds are specified manually at first so that an executable, editable model is created. Based on these results, the operation of the compressors are optimized in order to ensure a surge margin of 15 \% and to avoid choke in each operating point.}, language = {en} } @incollection{FuttererEgbers, author = {Futterer, Birgit and Egbers, Christoph}, title = {Quasi-stationary and chaotic convection in low rotating spherical shells}, series = {Advances in turbulence XII, proceedings of the 12th EUROMECH European Turbulence Conference, September, 2009, Marburg, Germany}, booktitle = {Advances in turbulence XII, proceedings of the 12th EUROMECH European Turbulence Conference, September, 2009, Marburg, Germany}, editor = {Eckhardt, Bruno}, publisher = {Springer}, address = {Berlin [u.a.]}, isbn = {978-3-642-03084-0}, pages = {97 -- 101}, language = {en} } @inproceedings{SitteImmohrHinrichsetal., author = {Sitte, B. and Immohr, J. and Hinrichs, O. and Meier, R. and Egbers, Christoph and Rath, H. J.}, title = {Rayleigh-Benard convection in dielectrophoretic force fields}, language = {en} } @misc{GrimmStreleKupkaLoewBasellietal., author = {Grimm-Strele, Hannes and Kupka, Friedrich and L{\"o}w-Baselli, Bernhard and Mundprecht, Eva and Zaussinger, Florian and Schiansky, Peter}, title = {Realistic simulations of stellar surface convection with ANTARES: I. Boundary conditions and model relaxation}, series = {New Astronomy}, volume = {34}, journal = {New Astronomy}, issn = {1384-1076}, doi = {10.1016/j.newast.2013.11.005}, pages = {278 -- 293}, language = {en} } @inproceedings{HarlanderWrightEgbers, author = {Harlander, Uwe and Wright, G. B. and Egbers, Christoph}, title = {Reconstruction of the 3D flow field in a differentially heated rotating annulus by synchronized particle image velocimetry and infrared thermography measurements}, series = {16th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, Portugal, 09-12 July, Proceedings, Calouste Gulbenkian Foundation, Lisbon, Portugal}, booktitle = {16th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, Portugal, 09-12 July, Proceedings, Calouste Gulbenkian Foundation, Lisbon, Portugal}, language = {en} } @inproceedings{HarlanderWrightEgbers, author = {Harlander, Uwe and Wright, G. B. and Egbers, Christoph}, title = {Reconstruction of the 3D flow field in a differentially heated rotating annulus laboratory experiment}, series = {European Geosciences Union (EGU), 9th General Assembly, Vienna, Austria, 22-27 April}, booktitle = {European Geosciences Union (EGU), 9th General Assembly, Vienna, Austria, 22-27 April}, language = {en} } @incollection{JehringZanoun, author = {Jehring, Lothar and Zanoun, El-Sayed}, title = {Reducing environmental impact by mean of active flow control}, language = {en} } @incollection{MerboldHasanuzzamanBuchwaldetal., author = {Merbold, Sebastian and Hasanuzzaman, Gazi and Buchwald, Tom and Schunk, Christoph and Schmeling, Daniel and Volkmann, Andr{\´e} and Brinkema, Robert and Hampel, Uwe and Schr{\"o}der, Andreas and Egbers, Christoph}, title = {Reference experiment for aerosol particle transport for dynamic situations}, series = {Experimentelle Str{\"o}mungsmechanik : 29. Fachtagung, 6.-8. September 2022, Ilmenau}, booktitle = {Experimentelle Str{\"o}mungsmechanik : 29. Fachtagung, 6.-8. September 2022, Ilmenau}, editor = {Cierpka, Christian}, publisher = {Deutsche Gesellschaft f{\"u}r Laser-Anemometrie - German Association for Laser Anemometry GALA e.V.}, address = {Karlsruhe}, isbn = {978-3-9816764-8-8}, pages = {8}, language = {en} } @misc{MerboldHasanuzzamanBuchwaldetal., author = {Merbold, Sebastian and Hasanuzzaman, Gazi and Buchwald, Tom and Schunk, Christoph and Schmeling, Daniel and Volkmann, Andr{\´e} and Brinkema, Robert and Hampel, Uwe and Schr{\"o}der, Andreas and Egbers, Christoph}, title = {Reference experiment on aerosol particle transport for dynamic situations}, series = {tm - Technisches Messen}, volume = {90}, journal = {tm - Technisches Messen}, number = {5}, issn = {2196-7113}, doi = {10.1515/teme-2022-0118}, pages = {13}, language = {en} } @misc{ZanounDurstNagib, author = {Zanoun, El-Sayed and Durst, F. and Nagib, H. M.}, title = {Refined Cf relation for turbulent channels and consequences for high Re experiments}, language = {en} } @misc{SchoenBorciaHarlanderetal., author = {Sch{\"o}n, F.-T. and Borcia, I. D. and Harlander, U. and Borcia, R. and Richter, S. and Bestehorn, M.}, title = {Resonant surface waves in an oscillating periodic tank with a submerged hill}, series = {Journal of Fluid Mechanics}, volume = {999 (2024)}, journal = {Journal of Fluid Mechanics}, doi = {10.1017/jfm.2024.885}, pages = {1 -- 18}, language = {en} } @misc{HarlanderSchoenBorciaetal., author = {Harlander, U. and Sch{\"o}n, F.-T. and Borcia, I. D. and Richter, S. and Borcia, R. and Bestehorn, M.}, title = {Resonant water-waves in ducts with different geometries: forced KdV solutions}, series = {European Journal of Mechanics - B/Fluids}, volume = {106}, journal = {European Journal of Mechanics - B/Fluids}, number = {July-August 2024}, issn = {0997-7546}, doi = {10.1016/j.euromechflu.2024.03.008}, pages = {107 -- 115}, language = {en} } @article{ZanounDurstNagib, author = {Zanoun, El-Sayed and Durst, F. and Nagib, H. M.}, title = {Response to "Comment on 'Evaluating the law of the wall in two-dimensional fully developed turbulent channel flows' "}, language = {en} } @misc{ZanounDewidarEgbers, author = {Zanoun, El-Sayed and Dewidar, Yasser and Egbers, Christoph}, title = {Reynolds number dependence of azimuthal and streamwise pipe flow structures}, series = {Journal of Fluid Mechanics}, volume = {Vol. 973}, journal = {Journal of Fluid Mechanics}, issn = {0022-1120}, doi = {10.1017/jfm.2023.700}, pages = {1 -- 36}, language = {en} } @misc{HarlanderWenzelEgbers, author = {Harlander, Uwe and Wenzel, Julia and Egbers, Christoph}, title = {Rotating annulus laboratory experiments with application to baroclinic channel flows with narrows}, language = {en} } @misc{ZaussingerHaunSzaboetal., author = {Zaussinger, Florian and Haun, Peter and Szabo, Peter and Travnikov, Vadim and Al-Kawwas, Mustafa and Egbers, Christoph}, title = {Rotating spherical gap convection in the GeoFlow International Space Station (ISS) experiment}, series = {Physical Review Fluids}, volume = {5}, journal = {Physical Review Fluids}, number = {6}, issn = {2469-990X}, doi = {10.1103/PhysRevFluids.5.063502}, pages = {23}, language = {en} } @incollection{ZanounDurstNagib, author = {Zanoun, El-Sayed and Durst, F. and Nagib, H. M.}, title = {Scaling Laws for Turbulent Channel and Pipe Flows over a Wide Range of Reynolds Number}, language = {de} } @inproceedings{AugensteinLeopoldRichard, author = {Augenstein, Edgar and Leopold, F. and Richard, H.}, title = {Schlieren Techniques in Comparison The Background Oriented Method versus Visualization with Holographic Filters}, language = {en} } @misc{KupkaLoschZaussingeretal., author = {Kupka, Friedrich and Losch, Martin and Zaussinger, Florian and Zweigle, Thomas}, title = {Semi-convection in the ocean and in stars: A multi-scale analysis}, series = {Meteorologische zeitschrift}, volume = {24}, journal = {Meteorologische zeitschrift}, number = {3}, issn = {0941-2948}, doi = {10.1127/metz/2015/0643}, pages = {343 -- 358}, abstract = {Fluid stratified by gravitation can be subject to a number of instabilities which eventually lead to a flow that causes enhanced mixing and transport of heat. The special case where a destabilizing temperature gradient counteracts the action of a stabilizing gradient in molecular weight is of interest to astrophysics (inside stars and giant planets) and geophysics (lakes, oceans) as well as to some engineering applications. The detailed dynamics of such a system depend on the molecular diffusivities of heat, momentum, and solute as well as system parameters including the ratio of the two gradients to each other. Further important properties are the formation and merging of well-defined layers in the fluid which cannot be derived from linear stability analysis. Moreover, the physical processes operate on a vast range of length and time scales. This has made the case of semi-convection, where a mean temperature gradient destabilizes the stratification while at the same time the mean molecular gradient tends to stabilize it, a challenge to physical modelling and to numerical hydrodynamical simulation. During the MetStr{\"o}m project the simulation codes ANTARES and MITgcm have been extended such that they can be used for the simulations of such flows. We present a comparison of effective diffusivities derived from direct numerical simulations. For both stars and the oceanic regimes, the Nusselt numbers (scaled diffusivities) follow similar relationships. Semi-convection quickly becomes inefficient, because the formation of layers limits vertical mixing. In contrast to the complementary saltfingering, these layers tend to damp instabilities so that effective diffusivities of salinity (concentration) are up to two orders of magnitudes smaller than in the former case.}, language = {en} } @misc{ZaussingerKupkaEgbersetal., author = {Zaussinger, Florian and Kupka, Friedrich and Egbers, Christoph and Neben, Matthias and H{\"u}cker, S. and Bahr, C. and Schmitt, M.}, title = {Semi-convective layer formation}, series = {Journal of Physics: Conference Series}, volume = {837}, journal = {Journal of Physics: Conference Series}, number = {1}, doi = {10.1088/1742-6596/837/1/012012}, pages = {7}, language = {en} } @misc{Zaussinger, author = {Zaussinger, Florian}, title = {Semiconvection}, language = {de} } @misc{Zaussinger, author = {Zaussinger, Florian}, title = {Semiconvection}, language = {en} } @misc{FuttererKrebsPlesaetal., author = {Futterer, Birgit and Krebs, Andreas and Plesa, Ana-Catalina and Zaussinger, Florian and Hollerbach, Rainer and Breuer, Doris and Egbers, Christoph}, title = {Sheet-like and plume-like thermal flow in a spherical convection experiment performed under microgravity}, series = {Journal of Fluid Mechanics}, volume = {vol. 735}, journal = {Journal of Fluid Mechanics}, issn = {1750-6859}, doi = {10.1017/jfm.2013.507}, pages = {647 -- 683}, language = {en} } @inproceedings{EgbersZaussinger, author = {Egbers, Christoph and Zaussinger, Florian}, title = {Simulation of geophysical fluid flows in spherical shells: The Geoflow experiments on ISS}, series = {Book of abstracts, School ISTROF 2016, Instabilities and Turbulence in Strato-Rotational Flows, July 11-13th, 2016, Le Havre}, booktitle = {Book of abstracts, School ISTROF 2016, Instabilities and Turbulence in Strato-Rotational Flows, July 11-13th, 2016, Le Havre}, language = {en} } @inproceedings{EgbersHollerbachChossat, author = {Egbers, Christoph and Hollerbach, Rainer and Chossat, P.}, title = {Simulation of geophysical fluid flows under microgravity}, language = {en} } @inproceedings{Egbers, author = {Egbers, Christoph}, title = {Simulation of Geophysical Fluid Flows under Microgravity (GeoFlow): Flow diagnostics and experiment concept for Fluid Science experiments}, series = {Proceedings of 11th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, 8-11th July 2002}, booktitle = {Proceedings of 11th International Symposium on Applications of Laser Techniques to Fluid Mechanics, Lisbon, 8-11th July 2002}, pages = {5}, language = {en} } @misc{SimonYaraslauSzaboetal., author = {Simon, K{\"u}hne and Yaraslau, Sliavin and Szabo, Peter and Carter, R. and Krebs, Andreas and Egbers, Christoph}, title = {Simultaneous particle image velocimetry and background oriented schlieren measurements of convective flows}, series = {Experimentelle Str{\"o}mungsmechanik, Hrsg.: B. Ruck et al.}, journal = {Experimentelle Str{\"o}mungsmechanik, Hrsg.: B. Ruck et al.}, publisher = {German Association for Laser Anemometry 26.8 GALA e.V.}, address = {Karlsruhe}, isbn = {978-3-9816764-4-0}, language = {en} } @misc{SzaboMeyerMeieretal., author = {Szabo, Peter and Meyer, Antoine and Meier, Martin and Motuz, Vasyl and Sliavin, Yaraslau and Egbers, Christoph}, title = {Simultaneous PIV and shadowgraph measurements of thermo-electrohydrodynamic convection in a differentially heated annulus}, series = {Technisches Messen}, volume = {89}, journal = {Technisches Messen}, number = {3}, issn = {2196-7113}, doi = {10.1515/teme-2021-0120}, pages = {148 -- 157}, language = {en} } @misc{HarlanderWenzelWangetal., author = {Harlander, Uwe and Wenzel, Julia and Wang, Yongtai and Alexandrov, Kiril and Egbers, Christoph}, title = {Simultaneous PIV- and thermography-measurements of partially blocked flow in a heated rotating annulus}, language = {en} }