@inproceedings{BorciaBorciaBestehornetal., author = {Borcia, Ion-Dan and Borcia, Rodica and Bestehorn, Michael and Borcia, C. and Dumitrascu, N. and Egbers, Christoph}, title = {Drops on cylindrical surfaces}, series = {7th Conference of the International Marangoni Association, Vienna (Austria), June 23-26, 2014}, booktitle = {7th Conference of the International Marangoni Association, Vienna (Austria), June 23-26, 2014}, publisher = {Techn. Univ.}, address = {Vienna}, pages = {S. 33}, language = {en} } @article{BorciaBorciaBestehorn, author = {Borcia, Rodica and Borcia, Ion-Dan and Bestehorn, Michael}, title = {Liquid layers on a patterned surface}, series = {Soft Matter}, volume = {4}, journal = {Soft Matter}, number = {12}, pages = {2368 -- 2372}, language = {en} } @misc{BorciaBorciaBestehornetal., author = {Borcia, Ion-Dan and Borcia, Rodica and Bestehorn, Michael and Richter, Stefan and Xu, Wenchao and Harlander, Uwe}, title = {Horizontal Faraday instability and parametric excitation in a circular channel}, series = {GAMM 2019, 90th Annual Meeting of the International Assoociation of Applied Mathematics and Mechanics, February 18-22, 2019, Vienna, Austria}, journal = {GAMM 2019, 90th Annual Meeting of the International Assoociation of Applied Mathematics and Mechanics, February 18-22, 2019, Vienna, Austria}, publisher = {TU Verlag}, address = {Wien}, isbn = {978-3-903024-84-7}, pages = {338}, language = {en} } @misc{BorciaBorciaBestehornetal., author = {Borcia, Rodica and Borcia, Ion-Dan and Bestehorn, Michael and Sharma, Deewakar and Amiroudine, Sakir}, title = {Phase field modeling in liquid binary mixtures: isothermal and non-isothermal problems}, series = {Physical Review Fluids}, volume = {7}, journal = {Physical Review Fluids}, number = {6}, issn = {2469-990X}, doi = {10.1103/PhysRevFluids.7.064005}, pages = {1 -- 19}, abstract = {The objective in the present paper is to study binary fluids with phase field modeling coupled with Navier-Stokes equations. An extended free energy is proposed to account for the continuous path from immiscible to miscible states. We consider fluid pairs that are immiscible for temperatures below the critical one (consolute temperature) and miscible above it. Our extended phase field equation permits us to move from the immiscible state (governed by the Cahn-Hilliard equation) to the miscible state (defined by the species diffusion equation). The scaling of interface tension and interface width with the distance to the critical point is highlighted. The whole system is mechanically excited showing Faraday instability of a flat interface. A linear stability analysis is performed for the stable case (interface waves) as well as for the unstable Faraday one. For the latter, a Floquet analysis shows the well-known Arnold's tongues as a function of the consolute temperature and depth layer. Moreover, two-dimensional finite difference simulations have been performed allowing us to model nonlinear flow patterns both in miscible and immiscible phases. Linear theory and nonlinear simulations show interesting results such as the diminishing of the wavelength of Faraday waves or a shift of the critical vibration amplitude when the consolute temperature is approached.}, language = {en} } @misc{BorciaPopescuBorcia, author = {Borcia, Rodica and Popescu, Sebastian and Borcia, Ion-Dan}, title = {IMA10: interfacial fluid dynamics and processes}, series = {European Physical Journal Special Topics}, volume = {232}, journal = {European Physical Journal Special Topics}, number = {4}, issn = {1951-6401}, doi = {10.1140/epjs/s11734-023-00798-5}, pages = {365 -- 366}, abstract = {MA10-special issue presents recent advances on interfacial fluid dynamics with applications in microfluidics, biology, engineering and geophysics.}, language = {en} } @inproceedings{BorciaBorciaBestehornetal., author = {Borcia, Ion-Dan and Borcia, Rodica and Bestehorn, Michael and Xu, Wenchao and Harlander, Uwe}, title = {Surface waves generated by libration in a circular channel}, series = {The 12th European Fluid Mechanics Conference, 9 September 2018 - 13 September 2018, Vienna, Austria}, booktitle = {The 12th European Fluid Mechanics Conference, 9 September 2018 - 13 September 2018, Vienna, Austria}, pages = {1}, language = {en} } @misc{BorciaBorciaXuetal., author = {Borcia, Ion-Dan and Borcia, Rodica and Xu, Wenchao and Bestehorn, Michael and Richter, Sebastian and Harlander, Uwe}, title = {Undular bores in a large circular channel}, series = {European Journal of Mechanics - B/Fluids}, volume = {79}, journal = {European Journal of Mechanics - B/Fluids}, issn = {0997-7546}, doi = {10.1016/j.euromechflu.2019.09.003}, pages = {67 -- 73}, abstract = {An experimental device previously developed for studying rotating baroclinic flows has been used to investigate undular bores formation, propagation and collision. Up to our knowledge this is the first experimental study of undular bores in a circular channel. For a setup without barriers, this geometry accomplishes in a natural way the periodic lateral boundary conditions, very often used in numerical simulations. An excellent agreement between the experiment and simulation has been achieved. The spatio-temporal structure of bores is well reproduced for the first few reflections or collisions.}, language = {en} } @misc{BorciaRichterBorciaetal., author = {Borcia, Ion-Dan and Richter, Sebastian and Borcia, Rodica and Sch{\"o}n, Franz-Theo and Harlander, Uwe and Bestehorn, Michael}, title = {Wave propagation in a circular channel: sloshing and resonance}, series = {The European Physical Journal Special Topics}, volume = {Vol. 232}, journal = {The European Physical Journal Special Topics}, number = {4}, issn = {1951-6401}, doi = {10.1140/epjs/s11734-023-00790-z}, pages = {461 -- 468}, abstract = {Surface wave resonance of a liquid (water) layer confined in a circular channel is studied both experimentally and numerically. For the experiment, eight unevenly distributed ultrasonic distance sensors measure the local height of the wave surface. The resonance curves show maxima only for odd multiples of the fundamental resonance frequency . We explained this behavior using a simple intuitive "ping-pong" like model. Collision of wave fronts can be observed for higher frequencies. Also, the wave reflection on the walls can be treated as wave collision with itself. The non-linearity seems to be weak in our study so the delay in the wave propagation before and after the collision is small. Time-space plots show localized propagating waves with high amplitudes for frequencies near resonance. Between the peaks low amplitude and harmonic patterns are observed. However, for higher frequencies, the frequency band for localized waves becomes wider. In the Fourier space-time plane, this can be observed as a point for the harmonic patterns or a superposition of two lines: one line parallel to wave-vector k axis corresponding to the excitation frequency and a second line with inclination given by wave propagation velocity . For planned future work, this result will help us to reconstruct the whole water surface elevation using time-series from only a few measurement points}, language = {en} } @misc{BorciaBorciaRichteretal., author = {Borcia, Ion-Dan and Borcia, Rodica and Richter, Sebastian and Xu, Wenchao and Bestehorn, Michael and Harlander, Uwe}, title = {Horizontal Faraday instability in a circular channel}, series = {Proceedings in Applied Mathematics and Mechanics (PAMM)}, volume = {19}, journal = {Proceedings in Applied Mathematics and Mechanics (PAMM)}, number = {1}, issn = {1617-7061}, doi = {10.1002/pamm.201900242}, pages = {2}, abstract = {We study surface waves in a circular channel placed on a rotating table. The tank can rotate with constant velocity and/or can oscillate. For a glycerin-water-solution with high viscosity, oscillation amplitudes about 20 cm and frequencies of 0.5 Hz, we observe surface patterns generated by a parametric instability. The circular geometry of the channel assures in a natural way the periodic lateral boundary conditions often used in the numerical simulations. Up to our knowledge this is the first experiment which evidences the horizontal Faraday instability in a container without walls blocking the flow in the oscillation direction. Experimental and numerical results are compared and discussed.}, language = {en} } @misc{BorciaBorciaBestehorn, author = {Borcia, Rodica and Borcia, Ion-Dan and Bestehorn, Michael}, title = {Can vibrations control drop motion?}, series = {Langmuir}, volume = {30}, journal = {Langmuir}, number = {47}, issn = {1520-5827}, doi = {10.1021/la503415r}, pages = {14113 -- 14117}, abstract = {We discuss a mechanism for controlled motion of drops with applications for microfluidics and microgravity. The mechanism is the following: a solid plate supporting a liquid droplet is simultaneously subject to lateral and vertical harmonic oscillations. In this way the symmetry of the back-and-forth droplet movement along the substrate under inertial effects is broken and thus will induce a net driven motion of the drop. We study the dependency of the traveled distance on the oscillation parameters (forcing amplitude, frequency, and phase shift between the two perpendicular oscillations) via phase field simulations. The internal flow structure inside the droplet is also investigated. We make predictions on resonance frequencies for drops on a substrate with a varying wettability.}, language = {en} } @article{BorciaBorciaBestehorn, author = {Borcia, Rodica and Borcia, Ion-Dan and Bestehorn, Michael}, title = {Drops on an arbitrarily wetting substrate: A phase field description}, language = {en} } @misc{BorciaBorciaBestehornetal., author = {Borcia, Rodica and Borcia, Ion-Dan and Bestehorn, Michael and Varlamova, Olga and Hoefner, Kevin and Reif, J{\"u}rgen}, title = {Drop Behavior Influenced by the Correlation Length on Noisy Surfaces}, series = {Langmuir}, volume = {35}, journal = {Langmuir}, doi = {10.1021/acs.langmuir.8b03878}, pages = {928 -- 934}, language = {en} } @misc{VarlamovaReifStolzetal., author = {Varlamova, Olga and Reif, J{\"u}rgen and Stolz, Michael and Borcia, Rodica and Borcia, Ion-Dan and Bestehorn, Michael}, title = {Wetting properties of LIPSS structured silicon surfaces}, series = {The European Physical Journal B}, volume = {92}, journal = {The European Physical Journal B}, number = {5}, issn = {1434-6036}, doi = {10.1140/epjb/e2019-90672-2}, pages = {8}, abstract = {The controlled dynamics of liquid drops via generation of specific wetting states on a solid surface is of great interests both in the fundamental and applied sciences. Considering that the wettability is strongly dependent on the surface topography and surface roughness, we investigate - through experiments and theory - the effect of laser-induced periodic surface structures (LIPSS) generated on silicon (100) targets as a control parameter of wetting properties. To obtain structured silicon surfaces with different morphological features, we patterned the surface by irradiation with femtosecond pulses from an amplified Ti:Sapphire laser system (790 nm/100 fs/1 kHz) at a fluence in the range of 0.4-1.2 J/cm2 on a spot with a diameter about of 100 μm. Variation of the applied irradiation dose results in surface modifications with the roughness about of a few tens of nanometers are ranging from regular LIPSS patterns with the lateral period of about 500-700 nm to complex agglomerations of 3-D microstructures with several-μm feature size. The theoretical study on the correlation of wetting properties with the surface topography has been performed within a phase field model. We found an excellent agreement of numerical results with experiments.}, language = {en} } @misc{BorciaBorciaHelbigetal., author = {Borcia, Rodica and Borcia, Ion-Dan and Helbig, Markus and Meier, Martin and Egbers, Christoph and Bestehorn, Michael}, title = {Dancing drops over vibrating substrates}, series = {The European Physical Journal Special Topics}, volume = {226}, journal = {The European Physical Journal Special Topics}, number = {6}, issn = {1951-6355}, doi = {10.1140/epjst/e2016-60202-6}, pages = {1297 -- 1306}, language = {en} } @misc{BorciaBorciaBestehorn, author = {Borcia, Rodica and Borcia, Ion-Dan and Bestehorn, Michael}, title = {Nonlinear dynamics of thin liqiud films consisting of two miscible components}, series = {Physical Review E}, volume = {86}, journal = {Physical Review E}, number = {5}, issn = {2470-0053}, doi = {10.1103/PhysRevE.86.056319}, pages = {056319}, abstract = {Recently, we systematically derived a system of two coupled conservation equations governing a thin liquid layer with a deformable surface composed of two completely miscible components [Phys. Fluids 22, 104102 (2010)]. One equation describes the location of the free surface and the second one the evolution of the mean concentration. This lubrication model was investigated previously in linearized form. The study is now extended to the fully nonlinear case of thin liquid films of a binary mixture (in one and two horizontal spatial dimensions) with and without heat transport. For an initially flat and motionless film heated from below, we analyze the component separation induced by the Soret effect. Nonlinear simulations show that the Soret effect can cause a multitude of interesting behaviors, such as oscillatory patterns and solitonlike structures (localized traveling drops or holes). A stronger component separation induced by stronger Soret effects favors faster-moving localized structures. For isothermal systems, we study the fusion and the mixing of two thin liquid films of different but perfectly miscible liquids. Marangoni-driven forces can cause delayed coalescence, ripple formation, and fingering patterns at the borderline between the two liquid layers. A systematic analysis for ripple pattern formation and finger instabilities at different diffusion constants shows that these phenomena appear more pronounced for lower diffusion in the system.}, language = {en} } @article{BorciaBorciaBestehorn, author = {Borcia, Ion-Dan and Borcia, Rodica and Bestehorn, Michael}, title = {Long wave instabilities in binary mixture thin liquid films}, language = {en} } @article{BorciaBorciaBestehorn, author = {Borcia, Ion-Dan and Borcia, Rodica and Bestehorn, Michael}, title = {Soret effect in thin liquid films:Localized running drops, holes and stripes}, language = {en} } @inproceedings{BorciaBorciaBestehornetal., author = {Borcia, Ion-Dan and Borcia, Rodica and Bestehorn, Michael and Egbers, Christoph}, title = {Drops on cylindrical wires}, series = {International Topical Team Workshop on Two-Phase Systems for Ground and Space Applications, ITTW 2013}, booktitle = {International Topical Team Workshop on Two-Phase Systems for Ground and Space Applications, ITTW 2013}, language = {en} } @misc{BestehornBorcia, author = {Bestehorn, Michael and Borcia, Ion-Dan}, title = {Thin film lubrication dynamics of a binarymixture}, language = {en} } @inproceedings{BorciaSeeligHarlanderetal., author = {Borcia, Ion-Dan and Seelig, Torsten and Harlander, Uwe and Egbers, Christoph}, title = {Inertial waves in rotating cylindrical geometry: mean flow interactions and attractors}, language = {en} } @inproceedings{BorciaHarlanderSeeligetal., author = {Borcia, Ion-Dan and Harlander, Uwe and Seelig, Torsten and Egbers, Christoph}, title = {Comparing the spectrum of wave attractor frequency bands and the eigenspectrum of fluid in a rotating annulus with inclined inner cylinder}, 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} } @inproceedings{SeeligHarlanderBorciaetal., author = {Seelig, Torsten and Harlander, Uwe and Borcia, Ion-Dan and Scurtu, Nicoleta and Egbers, Christoph and Klein, Marten and Ghasemi, Abouzar and Will, Andreas and Schaller, Eberhard}, title = {Inertial waves in rotating cylindrical annulus: theory, experiment and simulations}, 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} } @inproceedings{BorciaHarlanderSeeligetal., author = {Borcia, Ion-Dan and Harlander, Uwe and Seelig, Torsten and Egbers, Christoph}, title = {Comparing attractor frequency bands with eigen frequencies for a confined rotating fluid}, 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} } @misc{BorciaHarlander, author = {Borcia, Ion-Dan and Harlander, Uwe}, title = {Inertial waves in a rotating annulus with inclined inner cylinder: comparing the spectrum of wave attractor frequency bands and the eigenspectrum in the limit of zero inclination}, series = {Theoretical and Computational Fluid Dynamics}, volume = {27}, journal = {Theoretical and Computational Fluid Dynamics}, number = {3-4}, issn = {1432-2250}, doi = {10.1007/s00162-012-0278-6}, pages = {397 -- 413}, language = {en} } @inproceedings{RoddaBorciaHarlander, author = {Rodda, Costanza and Borcia, Ion-Dan and Harlander, Uwe}, title = {Experimental results on intertia gravity wave emission from baroclinic jets}, 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} } @misc{VinczeBorciaHarlander, author = {Vincze, Mikl{\´o}s and Borcia, Ion-Dan and Harlander, Uwe}, title = {Temperature fluctuations in a changing climate: an ensemble-based experimental approach}, series = {Scientific Reports}, volume = {7}, journal = {Scientific Reports}, issn = {2045-2322}, doi = {10.1038/s41598-017-00319-0}, pages = {254}, language = {en} } @misc{RoddaBorciaLeGaletal., author = {Rodda, Costanza and Borcia, Ion-Dan and Le Gal, Patrice and Vincze, Miklos and Harlander, Uwe}, title = {Baroclinic, Kelvin and inertia-gravity waves in the barostrat instability experiment}, series = {Geophysical \& Astrophysical Fluid Dynamics}, volume = {112}, journal = {Geophysical \& Astrophysical Fluid Dynamics}, number = {3}, issn = {1029-0419}, doi = {10.1080/03091929.2018.1461858}, pages = {175 -- 206}, 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} } @misc{RoddaHienAchatzetal., author = {Rodda, Costanza and Hien, Steffen and Achatz, Ulrich and Borcia, Ion-Dan and Le Gal, Patrice and Vincze, Miklos and Harlander, Uwe}, title = {Differentially heated rotating annulus experiments to study gravity wave emission from jets and fronts}, series = {17th European Turbulence Conference, ETC 2019, September 3 - 6, 2019, Torino, Italy}, journal = {17th European Turbulence Conference, ETC 2019, September 3 - 6, 2019, Torino, Italy}, address = {Turin}, pages = {1}, language = {en} } @misc{VinczeBozokiHereinetal., author = {Vincze, Miklos and Boz{\´o}ki, Tam{\´a}s and Herein, M{\´a}ty{\´a}s and Borcia, Ion-Dan and Rodda, Costanza and P{\´a}lfy, J{\´o}zsef and Nyerges, Anita and Harlander, Uwe}, title = {Climate impact of the Drake Passage opening: lessons from a minimalistic laboratory experiment}, series = {EGU General Assembly 2020, Online | 4-8 May 2020}, journal = {EGU General Assembly 2020, Online | 4-8 May 2020}, doi = {10.5194/egusphere-egu2020-5004}, language = {en} } @misc{LeGalHarlanderBorciaetal., author = {Le Gal, Patrice and Harlander, Uwe and Borcia, Ion-Dan and Le Diz{\`e}s, St{\´e}phane and Chen, J. and Favier, Benjamin}, title = {Instability of vertically stratified horizontal plane Poiseuille flow}, series = {Journal of Fluid Mechanics}, volume = {907}, journal = {Journal of Fluid Mechanics}, number = {R1}, issn = {1469-7645}, doi = {10.1017/jfm.2020.917}, pages = {1 -- 14}, language = {en} } @misc{VinczeBozokiHereinetal., author = {Vincze, Miklos and Boz{\´o}ki, Tam{\´a}s and Herein, M{\´a}ty{\´a}s and Borcia, Ion-Dan and Harlander, Uwe and Horics{\´a}nyi, Attila and Nyerges, Anita and Rodda, Costanza and P{\´a}l, Andr{\´a}s and P{\´a}lfy, J{\´o}zsef}, title = {The Drake Passage opening from an experimental fluid dynamics point of view}, series = {SScientific Reports}, volume = {11}, journal = {SScientific Reports}, issn = {2045-2322}, doi = {10.1038/s41598-021-99123-0}, pages = {11}, 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} } @inproceedings{SeeligHarlanderBorciaetal., author = {Seelig, Torsten and Harlander, Uwe and Borcia, Ion-Dan and Egbers, Christoph}, title = {Zonal mean flow excitation due to inertial waves propagating in the meridional plane}, 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} } @inproceedings{RoddaBorciaHarlander, author = {Rodda, Costanza and Borcia, Ion-Dan and Harlander, Uwe}, title = {Baroclinic wave laboratory experiment with radial heating and vertical stratification to study IGW emission from baroclinic fronts}, 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} } @inproceedings{RoddaBorciaHarlander, author = {Rodda, Costanza and Borcia, Ion-Dan and Harlander, Uwe}, title = {Experimental study of internal wave emission from baroclinic jets}, series = {11th European Fluid Mechanics Conference, Sept. 12-16, 2016, Sevilla, Spain}, booktitle = {11th European Fluid Mechanics Conference, Sept. 12-16, 2016, Sevilla, Spain}, language = {en} } @inproceedings{KleinGhasemiSeeligetal., author = {Klein, Marten and Ghasemi, Abouzar and Seelig, Torsten and Borcia, Ion-Dan and Harlander, Uwe and Will, Andreas}, title = {Mean flow generation and inertial wave attractors in a librating annulus: DNS and theory}, series = {European Geosciences Union, General Assembly 2015, Vienna, Austria, 13 April - 17 May 2015}, booktitle = {European Geosciences Union, General Assembly 2015, Vienna, Austria, 13 April - 17 May 2015}, publisher = {European Geophysical Society}, address = {Katlenburg-Lindau}, language = {en} } @inproceedings{KleinBorciaEgbersetal., author = {Klein, Marten and Borcia, Ion-Dan and Egbers, Christoph and Ghasemi, Abouzar and Harlander, Uwe and Kurgansky, Michael V. and Schaller, Eberhard and Seelig, Torsten and Will, Andreas}, title = {Inertial Waves and Wave Excitation Mechanisms in Annular Cavities: Simulations, Experiments and Theory}, series = {European Turbulence Conference ETC14, Lyon, 2013}, booktitle = {European Turbulence Conference ETC14, Lyon, 2013}, pages = {2}, language = {en} } @misc{BorciaBestehorn, author = {Borcia, Ion-Dan and Bestehorn, Michael}, title = {Simulation of pattern morphology in binary liquid mixtures}, language = {en} } @inproceedings{KleinGhasemiSeeligetal., author = {Klein, Marten and Ghasemi, Abouzar and Seelig, Torsten and Borcia, Ion-Dan and Harlander, Uwe and Will, Andreas}, title = {DNS of inertial wave attractors in a librating annular cavity with a height-dependent gap}, 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 = {122 -- 123}, language = {en} } @inproceedings{KleinGhasemiSeeligetal., author = {Klein, Marten and Ghasemi, Abouzar and Seelig, Torsten and Borcia, Ion-Dan and Harlander, Uwe and Will, Andreas}, title = {DNS of inertial wave attractors in a librating annulus with height-dependent gap width}, series = {15th European turbulence conference (ETC), Delft, The Netherlands (2015)}, booktitle = {15th European turbulence conference (ETC), Delft, The Netherlands (2015)}, abstract = {Direct numerical simulations (DNS) of inertial wave attractors have been carried out in a librating Taylor-Couette system with broken mirror symmetry in the radial-axial cross-section. The inertial wave excitation mechanism and its localisation at the edges was clarified by applying boundary layer theory. Additional resonance peaks in the simulated response spectra were found to agree with low-order wave attractors obtained by geometric ray tracing. Numerics and theory are in qualitative agreement with recent lab experiments.}, language = {en} } @inproceedings{BorciaHarlander, author = {Borcia, Ion-Dan and Harlander, Uwe}, title = {Inertial waves inside a liquid confined between two rotating coaxial cylinders: the case of small Ekman number}, 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{SeeligBorciaKleinetal., author = {Seelig, Torsten and Borcia, Ion-Dan and Klein, Marten and Ghasemi, Abouzar and Will, Andreas and Egbers, Christoph and Schaller, Eberhard and Harlander, Uwe}, title = {Inertial waves and wave attractors in a rotating annulus with inner or outer cylinder libration}, series = {European Geosciences Union (EGU), 10th General Assembly, Vienna, Austria, 07 - 12 April 2013}, booktitle = {European Geosciences Union (EGU), 10th General Assembly, Vienna, Austria, 07 - 12 April 2013}, 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} } @inproceedings{Borcia, author = {Borcia, Ion-Dan}, title = {Attractors, eigenvalues and mean flow interactions in a fluid confined between two co-rotating cylinders}, language = {en} } @misc{KleinSeeligKurganskyetal., author = {Klein, Marten and Seelig, Torsten and Kurgansky, Michael V. and Ghasemi, Abouzar and Borcia, Ion-Dan and Will, Andreas and Schaller, Eberhard and Egbers, Christoph and Harlander, Uwe}, title = {Inertial wave excitation and focusing in a liquid bounded by a frustum and a cylinder}, series = {Journal of Fluid Mechanics}, journal = {Journal of Fluid Mechanics}, number = {vol. 751}, issn = {1750-6859}, doi = {10.1017/jfm.2014.304}, pages = {255 -- 297}, abstract = {The mechanism of localized inertial wave excitation and its efficiency is investigated for an annular cavity rotating with Ω0 . Meridional symmetry is broken by replacing the inner cylinder with a truncated cone (frustum). Waves are excited by individual longitudinal libration of the walls. The geometry is non-separable and exhibits wave focusing and wave attractors. We investigated laboratory and numerical results for the Ekman number E ≈ 10-6. inclination α = 5.71◦ and libration amplitudes ε 0.2 within the inertial wave band 0 < ω < 2Ω0 . Under the assumption that the inertial waves do not essentially affect the boundary-layer structure, we use classical boundary-layer analysis to study oscillating Ekman layers over a librating wall that is at an angle α = 0 to the axis of rotation. The Ekman layer erupts at frequency ω = f∗, where f∗ ≡ 2Ω0 sin α is the effective Coriolis parameter in a plane tangential to the wall. For the selected inclination this eruption occurs for the forcing frequency ω/Ω0 = 0.2. For the librating lids eruption occurs at ω/Ω0 = 2. The study reveals that the frequency dependence of the total kinetic energy Kω of the excited wave field is strongly connected to the square of the Ekman pumping velocity wE (ω) that, in the linear limit, becomes singular when the boundary layer erupts. This explains the frequency dependence of non-resonantly excited waves. By the localization of the forcing, the two configurations investigated, (i) frustum libration and (ii) lids together with outer cylinder in libration, can be clearly distinguished by their response spectra. Good agreement was found for the spatial structure of low-order wave attractors and periodic orbits (both characterized by a small number of reflections) in the frequency windows predicted by geometric ray tracing. For 'resonant' frequencies a significantly increased total bulk energy was found, while the energy in the boundary layer remained nearly constant. Inertial wave energy enters the bulk flow via corner beams, which are parallel to the characteristics of the underlying Poincar{\´e} problem. Numerical simulations revealed a mismatch between the wall-parallel mass fluxes near the corners. This leads to boundary-layer eruption and the generation of inertial waves in the corners.}, language = {en} } @misc{HarlanderLeGalBorciaetal., author = {Harlander, Uwe and Le Gal, Patrice and Borcia, Ion-Dan and Le Diz{\`e}s, St{\´e}phane and Chen, Jun and Favier, Benjamin}, title = {The linear instability of the stratified plane Poiseuille flow}, series = {17th European Turbulence Conference, ETC 2019, September 3 - 6, 2019, Torino, Italy}, journal = {17th European Turbulence Conference, ETC 2019, September 3 - 6, 2019, Torino, Italy}, address = {Turin}, pages = {1}, language = {en} }