@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{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{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{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{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{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} } @misc{SchoenHarlanderBorciaetal., author = {Sch{\"o}n, Franz-Theo and Harlander, Uwe and Borcia, Ion Dan and Borcia, Rodica and Bestehorn, Michael}, title = {Mean fluid transport in an oscillating circular channel with asymmetric forcing}, series = {Water waves : an interdisciplinary journal}, volume = {2025}, journal = {Water waves : an interdisciplinary journal}, publisher = {Birkh{\"a}user, part of Springer Nature}, address = {Basel}, issn = {2523-3688}, doi = {10.1007/s42286-025-00121-w}, pages = {1 -- 21}, abstract = {We investigate surface waves in an oscillating circular channel with local topography. The focus is on spatially or temporally breaking this dynamic system's symmetry. Asymmetrical wave dynamics and a mean flux excitation are detected to varying degrees, depending on the two input parameters, fluid depth and the tank's oscillation frequency. The fluid resonates around multiples of the fundamental eigenfrequency of the channel. The development of solitary wave-trains (undular bores) is observed in these resonance bands. A particle image velocimetry system measures the velocity field in the vertical plane of the free surface flow. Moreover, we are using 17 evenly distributed ultrasonic sensors to measure the surface displacement. This makes it possible to find out how strongly the mean flux depends on the resonance frequencies and to study the influence of the surface waves on the symmetry breaking. A numerical long-wave model helps to isolate the various factors influencing the mean flux.}, language = {en} } @article{BorciaMerktBestehorn, author = {Borcia, Rodica and Merkt, Domnic and Bestehorn, Michael}, title = {A phase-field description of surface-tension-driven instability}, language = {en} }