TY - CHAP A1 - Borcia, Ion-Dan A1 - Borcia, Rodica A1 - Bestehorn, Michael A1 - Borcia, C. A1 - Dumitrascu, N. A1 - Egbers, Christoph T1 - Drops on cylindrical surfaces T2 - 7th Conference of the International Marangoni Association, Vienna (Austria), June 23-26, 2014 Y1 - 2014 UR - http://ima7.conf.tuwien.ac.at/AbstractsIMA7.pdf SP - S. 33 PB - Techn. Univ. CY - Vienna ER - TY - JOUR A1 - Borcia, Rodica A1 - Borcia, Ion-Dan A1 - Bestehorn, Michael T1 - Liquid layers on a patterned surface JF - Soft Matter Y1 - 2008 UR - 1744-6848 VL - 4 IS - 12 SP - 2368 EP - 2372 ER - TY - GEN A1 - Borcia, Ion-Dan A1 - Borcia, Rodica A1 - Bestehorn, Michael A1 - Richter, Stefan A1 - Xu, Wenchao A1 - Harlander, Uwe T1 - Horizontal Faraday instability and parametric excitation in a circular channel T2 - GAMM 2019, 90th Annual Meeting of the International Assoociation of Applied Mathematics and Mechanics, February 18-22, 2019, Vienna, Austria Y1 - 2018 UR - https://jahrestagung.gamm-ev.de/images/2019/Photos/GAMM2019_BookofAbstracts.pdf SN - 978-3-903024-84-7 SP - 338 PB - TU Verlag CY - Wien ER - TY - GEN A1 - Borcia, Rodica A1 - Borcia, Ion-Dan A1 - Bestehorn, Michael A1 - Sharma, Deewakar A1 - Amiroudine, Sakir T1 - Phase field modeling in liquid binary mixtures: isothermal and non-isothermal problems T2 - Physical Review Fluids N2 - 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. KW - Binary fluids KW - Drop coalescence KW - Drop interactions KW - Drops & bubbles KW - Microfluidics Y1 - 2022 UR - https://journals.aps.org/prfluids/abstract/10.1103/PhysRevFluids.7.064005 U6 - https://doi.org/10.1103/PhysRevFluids.7.064005 SN - 2469-990X VL - 7 IS - 6 SP - 1 EP - 19 ER - TY - GEN A1 - Borcia, Rodica A1 - Popescu, Sebastian A1 - Borcia, Ion-Dan T1 - IMA10: interfacial fluid dynamics and processes T2 - European Physical Journal Special Topics N2 - MA10–special issue presents recent advances on interfacial fluid dynamics with applications in microfluidics, biology, engineering and geophysics. KW - Fluid Dynamics KW - Instabilities Droplets Y1 - 2023 U6 - https://doi.org/10.1140/epjs/s11734-023-00798-5 SN - 1951-6401 SN - 1951-6355 VL - 232 IS - 4 SP - 365 EP - 366 ER - TY - CHAP A1 - Borcia, Ion-Dan A1 - Borcia, Rodica A1 - Bestehorn, Michael A1 - Xu, Wenchao A1 - Harlander, Uwe T1 - Surface waves generated by libration in a circular channel T2 - The 12th European Fluid Mechanics Conference, 9 September 2018 – 13 September 2018, Vienna, Austria Y1 - 2018 UR - http://info.tuwien.ac.at/efmc12/EFMC12_program_v3.2.pdf 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 - 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 - Borcia, Ion-Dan A1 - Borcia, Rodica A1 - Richter, Sebastian A1 - Xu, Wenchao A1 - Bestehorn, Michael A1 - Harlander, Uwe T1 - Horizontal Faraday instability in a circular channel T2 - Proceedings in Applied Mathematics and Mechanics (PAMM) N2 - 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. KW - Faraday instability KW - Numerical solutions Y1 - 2019 UR - https://onlinelibrary.wiley.com/doi/abs/10.1002/pamm.201900242 U6 - https://doi.org/10.1002/pamm.201900242 SN - 1617-7061 VL - 19 IS - 1 ER - TY - GEN A1 - Borcia, Rodica A1 - Borcia, Ion-Dan A1 - Bestehorn, Michael T1 - Can vibrations control drop motion? T2 - Langmuir N2 - 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. Y1 - 2014 UR - http://pubs.acs.org/doi/abs/10.1021/la503415r U6 - https://doi.org/10.1021/la503415r SN - 1520-5827 SN - 1864-5631 VL - 30 IS - 47 SP - 14113 EP - 14117 ER -