TY - GEN A1 - Borcia, Ion-Dan A1 - Richter, Sebastian A1 - Borcia, Rodica A1 - Schön, Franz-Theo A1 - Harlander, Uwe A1 - Bestehorn, Michael T1 - Wave propagation in a circular channel: sloshing and resonance T2 - The European Physical Journal Special Topics N2 - 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 Y1 - 2023 UR - https://link.springer.com/article/10.1140/epjs/s11734-023-00790-z U6 - https://doi.org/10.1140/epjs/s11734-023-00790-z SN - 1951-6401 SN - 1951-6355 VL - Vol. 232 IS - 4 SP - 461 EP - 468 ER - TY - GEN A1 - Harlander, Uwe A1 - Sukhanovskii, Andrei A1 - Abide, Stéphane A1 - Borcia, Ion-Dan A1 - Popova, Elene A1 - Rodda, Costanza A1 - Vasiliev, Andrei A1 - Vincze, Miklos T1 - New Laboratory Experiments to Study the Large-Scale Circulation and Climate Dynamics T2 - Atmosphere N2 - 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. Y1 - 2023 UR - https://www.mdpi.com/2073-4433/14/5/836 U6 - https://doi.org/10.3390/atmos14050836 VL - 14 IS - 5 ER - TY - GEN A1 - Harlander, Uwe A1 - Borcia, Ion-Dan A1 - Vincze, Miklos A1 - Rodda, Costanza T1 - Probability Distribution of Extreme Events in a Baroclinic Wave Laboratory Experiment T2 - Fluids N2 - 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. Y1 - 2022 U6 - https://doi.org/10.3390/fluids7080274 SN - 2311-5521 VL - 7 IS - 8 ER - TY - GEN A1 - Le Gal, Patrice A1 - Harlander, Uwe A1 - Borcia, Ion-Dan A1 - Le Dizès, Stéphane A1 - Chen, J. A1 - Favier, Benjamin T1 - Instability of vertically stratified horizontal plane Poiseuille flow T2 - Journal of Fluid Mechanics Y1 - 2021 U6 - https://doi.org/10.1017/jfm.2020.917 SN - 1469-7645 SN - 0022-1120 VL - 907 IS - R1 SP - 1 EP - 14 ER - TY - GEN A1 - Vincze, Miklos A1 - Bozóki, Tamás A1 - Herein, Mátyás A1 - Borcia, Ion-Dan A1 - Harlander, Uwe A1 - Horicsányi, Attila A1 - Nyerges, Anita A1 - Rodda, Costanza A1 - Pál, András A1 - Pálfy, József T1 - The Drake Passage opening from an experimental fluid dynamics point of view T2 - SScientific Reports Y1 - 2021 U6 - https://doi.org/10.1038/s41598-021-99123-0 SN - 2045-2322 VL - 11 ER - TY - GEN A1 - Vincze, Miklos A1 - Bozóki, Tamás A1 - Herein, Mátyás A1 - Borcia, Ion-Dan A1 - Rodda, Costanza A1 - Pálfy, József A1 - Nyerges, Anita A1 - Harlander, Uwe T1 - Climate impact of the Drake Passage opening: lessons from a minimalistic laboratory experiment T2 - EGU General Assembly 2020, Online | 4–8 May 2020 Y1 - 2020 U6 - https://doi.org/10.5194/egusphere-egu2020-5004 ER - TY - GEN A1 - Borcia, Ion-Dan A1 - Borcia, Rodica A1 - Xu, Wenchao A1 - Bestehorn, Michael A1 - Richter, Sebastian A1 - Harlander, Uwe T1 - Undular bores in a large circular channel T2 - European Journal of Mechanics - B/Fluids N2 - 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. KW - Undular bores KW - Bore collision KW - Periodical boundary conditions Y1 - 2020 UR - https://www.sciencedirect.com/science/article/pii/S0997754619300706?via%3Dihub U6 - https://doi.org/10.1016/j.euromechflu.2019.09.003 SN - 0997-7546 VL - 79 SP - 67 EP - 73 ER - TY - GEN A1 - Harlander, Uwe A1 - Borcia, Ion-Dan A1 - Krebs, Andreas T1 - Nonnormality increases variance of gravity waves trapped in a tilted box T2 - Geophysical & Astrophysical Fluid Dynamics Y1 - 2019 U6 - https://doi.org/10.1080/03091929.2018.1549660 SN - 1029-041 VL - 113 IS - 5/6 SP - 602 EP - 622 ER - TY - GEN A1 - Rodda, Costanza A1 - Hien, Steffen A1 - Achatz, Ulrich A1 - Borcia, Ion-Dan A1 - Le Gal, Patrice A1 - Vincze, Miklos A1 - Harlander, Uwe T1 - Differentially heated rotating annulus experiments to study gravity wave emission from jets and fronts T2 - 17th European Turbulence Conference, ETC 2019, September 3 - 6, 2019, Torino, Italy Y1 - 2019 UR - http://www.symposium.it/files/eventi/84/etc-2019-561.pdf CY - Turin ER - TY - GEN A1 - Harlander, Uwe A1 - Le Gal, Patrice A1 - Borcia, Ion-Dan A1 - Le Dizès, Stéphane A1 - Chen, Jun A1 - Favier, Benjamin T1 - The linear instability of the stratified plane Poiseuille flow T2 - 17th European Turbulence Conference, ETC 2019, September 3 - 6, 2019, Torino, Italy Y1 - 2019 UR - http://www.symposium.it/files/eventi/84/etc-2019-561.pdf CY - Turin ER -