TY - GEN A1 - Bestehorn, Michael A1 - Bestehorn, Michael A1 - Michelitsch, Thomas M. A1 - Collet, Bernard A. A1 - Riascos, Alejandro P. A1 - Nowakowski, Andrzej. F. T1 - Simple model of epidemic dynamics with memory effects T2 - Physical Review E N2 - We introduce a compartment model with memory for the dynamics of epidemic spreading in a constant population of individuals. Each individual is in one of the states S=susceptible, I=infected, or R=recovered (SIR model). In state R an individual is assumed to stay immune within a finite-time interval. In the first part, we introduce a random lifetime or duration of immunity which is drawn from a certain probability density function. Once the time of immunity is elapsed an individual makes an instantaneous transition to the susceptible state. By introducing a random duration of immunity a memory effect is introduced into the process which crucially determines the epidemic dynamics. In the second part, we investigate the influence of the memory effect on the space-time dynamics of the epidemic spreading by implementing this approach into computer simulations and employ a multiple random walker's model. If a susceptible walker meets an infectious one on the same site, then the susceptible one gets infected with a certain probability. The computer experiments allow us to identify relevant parameters for spread or extinction of an epidemic. In both parts, the finite duration of immunity causes persistent oscillations in the number of infected individuals with ongoing epidemic activity preventing the system from relaxation to a steady state solution. Such oscillatory behavior is supported by real-life observations and not captured by the classical standard SIR model. KW - Bifurcations KW - Diseases KW - Dynamics of networks KW - Patterns in complex systems KW - Nonlinear Dynamics KW - Interdisciplinary Physics KW - Biological Physics Y1 - 2022 UR - https://journals.aps.org/pre/abstract/10.1103/PhysRevE.105.024205 U6 - https://doi.org/10.1103/PhysRevE.105.024205 SN - 2470-0045 VL - 105 IS - 2 SP - 024205-1 EP - 024205-10 ER - TY - GEN A1 - Varlamova, Olga A1 - Reif, Jürgen A1 - Stolz, Michael A1 - Borcia, Rodica A1 - Borcia, Ion-Dan A1 - Bestehorn, Michael T1 - Wetting properties of LIPSS structured silicon surfaces T2 - The European Physical Journal B N2 - 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. Y1 - 2019 U6 - https://doi.org/10.1140/epjb/e2019-90672-2 SN - 1434-6036 SN - 1434-6028 VL - 92 IS - 5 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Neuffer, Kai T1 - Surface Patterns of Laterally Extended Thin Liquid Films in Three Dimensions JF - Physical review letters Y1 - 2001 SN - 1079-7114 VL - 87 IS - 4 SP - 046101 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Merkt, Domnic A1 - Enculescu, Mihaela T1 - Entstehung und Dynamik makroskopischer Strukturen in Systemen fern vom Gleichgewicht JF - Forum der Forschung Y1 - 2005 SN - 0947-6989 VL - 9 IS - 18 SP - 31 EP - 40 ER - TY - GEN A1 - Varlamova, Olga A1 - Costache, Florenta Adriana A1 - Reif, Jürgen A1 - Bestehorn, Michael T1 - Self-organized pattern formation upon femtosecond laser ablation by circularly polarized light T2 - Applied Surface Science KW - femtosecond laser ablation KW - nanostructures KW - self-organization Y1 - 2006 SN - 0169-4332 VL - 252 IS - 13 SP - 4702 EP - 4706 ER - TY - CHAP A1 - Bestehorn, Michael A1 - Haken, H. T1 - Pattern Formation and Transients in the Convection Instability Y1 - 1985 ER - TY - CHAP A1 - Bestehorn, Michael A1 - Friedrich, R. A1 - Haken, H. T1 - Modulated Traveling Waves in Nonequilibrium Systems KW - 2D Order Parameter Models Y1 - 1990 ER - TY - JOUR A1 - Bestehorn, Michael T1 - Stationary and Traveling Pulses of the 2D Complex Ginzburg-Landau Equation KW - 2D Order Parameter Models Y1 - 1991 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Fantz, M. A1 - Friedrich, R. A1 - Haken, H. A1 - Pérez-García, C. T1 - Spiral Patterns in Thermal Convection KW - 2D Order Parameter Models Y1 - 1992 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Fantz, M. A1 - Friedrich, R. A1 - Haken, H. T1 - Pattern formation in rotating Bénard convection KW - 2D Order Parameter Models Y1 - 1992 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Pérez-García, C. T1 - Coexistence of Patterns with Different Symmetries in Bénard-Marangoni Convection Y1 - 1987 ER - TY - JOUR A1 - Thess, A. A1 - Bestehorn, Michael T1 - Planform Selection in Bénard-Marangoni-Convection: l-hexagons versus g-hexagons Y1 - 1995 ER - TY - JOUR A1 - Pérez-García, C. A1 - Echebarria, B. A1 - Bestehorn, Michael T1 - Thermal Properties in Surface-Tension-Driven Convection Y1 - 1998 ER - TY - CHAP A1 - Vaerenbergh, S. van A1 - Legros, J. C. A1 - Colinet, P. A1 - Velarde, M. G. A1 - Bestehorn, Michael A1 - Lebon, G. A1 - Thess, A. A1 - Karcher, C. T1 - Processes With Double Diffusive Instabilities Studied in Microgravity T2 - The 2nd European Symposium on Utilisation of the International Space Station, 16 - 18 November 1998, ESTEC, Noordwijk, The Netherlands Y1 - 1999 SN - 92-9092-732-1 SP - 241 EP - 248 PB - ESA Publ. CY - Noordwijk ER - TY - JOUR A1 - Bestehorn, Michael A1 - Fantz, M. A1 - Friedrich, R. A1 - Haken, H. T1 - Hexagonal and Spiral Patterns of Thermal Convection KW - 2D Order Parameter Models Y1 - 1993 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Neufeld, M. A1 - Friedrich, R. A1 - Haken, H. T1 - Pattern formation in rotating Bénard convection KW - 2D Order Parameter Models Y1 - 1994 ER - TY - JOUR A1 - Herrero, H. A1 - Pérez-García, C. A1 - Bestehorn, Michael T1 - Stability of fronts separating domains with different symmetries in hydrodynamical instabilities KW - 2D Order Parameter Models Y1 - 1994 ER - TY - CHAP A1 - Bestehorn, Michael A1 - Friedrich, R. T1 - Natural Patterns in Nonequilibrium Systems, in A Perspective Look at Nonlinear Media - From Physics to Biology and Social Sciences KW - 2D Order Parameter Models Y1 - 1998 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Friedrich, R. T1 - Rotationally invariant order parameter equations for natural patterns in nonequilibrium systems KW - 2D Order Parameter Models Y1 - 1999 ER - TY - JOUR A1 - Thiele, Uwe A1 - Velarde, M. G. A1 - Neuffer, Kai A1 - Bestehorn, Michael A1 - Pomeau, Y. T1 - Sliding drops in the diffusive interface model coupled to hydrodynamics JF - Physical Review E Y1 - 2001 SN - 1550-2376 VL - 64 IS - 4 SP - 061601 ER - TY - JOUR A1 - Thiele, Uwe A1 - Neuffer, Kai A1 - Bestehorn, Michael A1 - Pomeau, Y. A1 - Velarde, M. G. T1 - Sliding drops on an inclined plane JF - Colloids and Surfaces A Y1 - 2002 UR - 0927-7757 VL - 206 IS - 1-3 SP - 87 EP - 104 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Pototsky, Andrey A1 - Thiele, Uwe T1 - 3D Large scale Marangoni convection in liquid films Y1 - 2003 ER - TY - JOUR A1 - Thiele, Uwe A1 - Brusch, L. A1 - Bestehorn, Michael A1 - Bär, Marcus T1 - Modelling thin-film dewetting on structured substrates and templates Y1 - 2003 ER - TY - JOUR A1 - Pototsky, Andrey A1 - Bestehorn, Michael A1 - Thiele, Uwe T1 - Control of the structuring of thin softmatter films by means of different types of external disturbance Y1 - 2004 ER - TY - JOUR A1 - Nitschke, K. A1 - Bestehorn, Michael A1 - Thess, A. T1 - Square Cells in Surface-Tension-Driven Bénard Convection Y1 - 1998 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Colinet, P. T1 - Bénard–Marangoni convection of a binary mixture as an example of an oscillatory bifurcation under strong symmetry-breaking effects JF - Physica D: Nonlinear Phenomena Y1 - 2000 SN - 1872-8022 VL - 145 IS - 1-2 SP - 84 EP - 109 ER - TY - JOUR A1 - Merkt, Domnic A1 - Bestehorn, Michael T1 - Bénard-Marangoni convection in a stronglyevaporating fluid Y1 - 2003 ER - TY - JOUR A1 - Colinet, P. A1 - Joannes, L. A1 - Iorio, C. S. A1 - Haut, B. A1 - Bestehorn, Michael A1 - Lebon, G. A1 - Legros, J. C. T1 - Interfacial turbulence in evaporating liquids: Theory and preliminary results of the ITEL-Master 9 sounding rocket experiment Y1 - 2003 ER - TY - JOUR A1 - Borcia, Rodica A1 - Merkt, Domnic A1 - Bestehorn, Michael T1 - A phase-field description of surface-tension-driven instability Y1 - 2004 ER - TY - JOUR A1 - Borcia, Rodica A1 - Bestehorn, Michael T1 - Phase-field simulations for evaporation with convection in liquid-vapor systems JF - The European physical journal B Y1 - 2005 SN - 1434-6028 VL - 44 IS - 1 SP - 101 EP - 108 ER - TY - JOUR A1 - Borcia, Rodica A1 - Bestehorn, Michael T1 - Phase field models for Marangoni convection in planar layers Y1 - 2006 ER - TY - JOUR A1 - Borcia, Rodica A1 - Merkt, Domnic A1 - Bestehorn, Michael T1 - Convective patterns in liquid-vaporsystems with diffuse interface Y1 - 2006 ER - TY - JOUR A1 - Borcia, Rodica A1 - Bestehorn, Michael T1 - Phase field models and Marangoni flows Y1 - 2007 ER - TY - JOUR A1 - Millán-Rodriguez, J. A1 - Pérez-García, C. A1 - Bestehorn, Michael A1 - Fantz, M. A1 - Friedrich, R. T1 - Pattern Formation in Convection of Rotating Fluids with Broken Vertical Symmetry Y1 - 1992 ER - TY - JOUR A1 - Bestehorn, Michael T1 - Numerical Results of 3D Stationary Convection in a Binary Mixture Y1 - 1993 ER - TY - JOUR A1 - Bestehorn, Michael T1 - Phase and Amplitude Instabilities for Bénard-Marangoni Convection in Fluid Layers with Large Aspect Ratio Y1 - 1993 ER - TY - JOUR A1 - Bestehorn, Michael T1 - Pattern Selection in Bénard-Marangoni Convection Y1 - 1994 ER - TY - JOUR A1 - Millán-Rodriguez, J. A1 - Bestehorn, Michael A1 - Pérez-García, C. A1 - Friedrich, R. A1 - Neufeld, M. T1 - Defects Motion in Rotating Fluids Y1 - 1995 ER - TY - GEN A1 - Bestehorn, Michael T1 - Square Patterns in Bénard-Marangoni Convection Y1 - 1996 ER - TY - JOUR A1 - Bestehorn, Michael T1 - Two Layer Model Showing a Variety of Pattern Types near Nonequilibrium Phase Transitions Y1 - 1996 ER - TY - GEN A1 - Borcia, Rodica A1 - Bestehorn, Michael T1 - Different behaviours of delayed fusion between drops with miscible liquids T2 - Physical review E Y1 - 2010 SN - 1063-651X VL - 82 IS - 3 SP - 036312 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Grigorieva, E. V. A1 - Haken, H. A1 - Kaschenko, S. A. T1 - Order Parameters for Class-B Lasers With a Long Time Delayed Feedback Y1 - 2000 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Grigorieva, E. V. A1 - Kaschenko, S. A. T1 - Spatio-Temporal Structures in a Model With Delay And Diffusion Y1 - 2004 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Grigorieva, E. V. T1 - Formation and Propagation of Localized States in Extended Systems Y1 - 2004 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Pérez-García, C. T1 - Modulated Rolls and Traveling Waves in a Secondary Convective Instability Y1 - 1991 ER - TY - JOUR A1 - Bestehorn, Michael T1 - Numerical Results of 3D-Convection in a Binary Mixture for a Positive Separation Ratio Y1 - 1992 ER - TY - JOUR A1 - Bestehorn, Michael T1 - Convection in thick and thin fluid layers with a free surface - The Influence of Evaporation Y1 - 2007 ER - TY - JOUR A1 - Borcia, Rodica A1 - Bestehorn, Michael T1 - Phase field simulations for drops and bubbles Y1 - 2007 ER - TY - JOUR A1 - Borcia, Rodica A1 - Borcia, Ion-Dan A1 - Bestehorn, Michael T1 - Drops on an arbitrarily wetting substrate: A phase field description Y1 - 2008 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, Rodica A1 - Bestehorn, Michael T1 - Controlled Pattern Formation in Thin Liquid Layers Y1 - 2009 ER - TY - GEN A1 - Borcia, Rodica A1 - Bestehorn, Michael T1 - A Phase Field Description of Spatio-Temporal Behavior in Thin Liquid Layers Y1 - 2010 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Haken, H. T1 - A Calculation of Transient Solutions Describing Roll and Hexagon Formation in the Convection Instability Y1 - 1983 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Haken, H. T1 - Transient Patterns of the Convection Instability: A Model Calculation KW - 2D Order Parameter Models Y1 - 1984 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Friedrich, R. A1 - Haken, H. T1 - The Oscillatory Instability of a Spatially Homogeneous State in Large Aspect Systems of Fluid Dynamics KW - 2D Order Parameter Models Y1 - 1988 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Friedrich, R. A1 - Haken, H. T1 - Two-dimensional Traveling Wave Patterns in Nonequilibrium Systems Y1 - 1989 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Friedrich, R. A1 - Haken, H. T1 - Traveling Waves in Nonequilibrium Systems KW - 2D Order Parameter Models Y1 - 1989 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Friedrich, R. A1 - Haken, H. T1 - Modulated Traveling Waves in Nonequilibrium Systems: The Blinking State Y1 - 1989 ER - TY - GEN A1 - Pototsky, Andrey A1 - Archer, Andrew J. A1 - Bestehorn, Michael A1 - Merkt, Domnic A1 - Savelev, S. A1 - Marchesoni, F. T1 - Collective shuttling of attracting particles in asymmetric narrow channels Y1 - 2010 ER - TY - GEN A1 - Bestehorn, Michael A1 - Tyvand, Peder A. T1 - Merging and colliding bores Y1 - 2009 ER - TY - GEN A1 - Tyvand, Peder A. A1 - Bestehorn, Michael T1 - Diffraction of Poincare waves by a change in ocean depth Y1 - 2009 ER - TY - JOUR A1 - Friedrich, R. A1 - Bestehorn, Michael A1 - Haken, H. T1 - Pattern Formation in Convective Instabilities Y1 - 1990 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Haken, H. T1 - Traveling Waves and Pulses in a Two-Dimensional Large-Aspect-Ratio System JF - Physical Review A Y1 - 1990 SN - 0556-2791 VL - 42 IS - 12 SP - 7195 EP - 7203 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Haken, H. T1 - Associative Memory of a Dynamical System: The Example of the Convection Instability JF - Zeitschrift für Physik B Y1 - 1991 SN - 1431-584 SN - 0722-3277 VL - 82 IS - 2 SP - 305 EP - 308 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Pérez-García, C. T1 - Study of a Model of Thermal Convection in Cylindrical Containers KW - 2D Order Parameter Models Y1 - 1992 ER - TY - JOUR A1 - Millán-Rodriguez, J. A1 - Bestehorn, Michael A1 - Pérez-García, C. A1 - Neufeld, M. A1 - Friedrich, R. T1 - Motion of Defects in Rotating Fluids Y1 - 1994 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Neufeld, M. A1 - Friedrich, R. A1 - Haken, H. T1 - Comment on Spiral pattern formation in Rayleigh-Bénard Convection Y1 - 1994 ER - TY - JOUR A1 - Borcia, Rodica A1 - Bestehorn, Michael T1 - Phase-field model for Marangoni convection in liquid-gas systems with deformable interface Y1 - 2003 ER - TY - JOUR A1 - Pototsky, Andrey A1 - Bestehorn, Michael A1 - Merkt, Domnic A1 - Thiele, Uwe T1 - Alternative pathways of dewetting for a thin two-layer film of soft matter Y1 - 2004 U6 - https://doi.org/10.48550/arXiv.nlin/0401042 ER - TY - JOUR A1 - Merkt, Domnic A1 - Pototsky, Andrey A1 - Bestehorn, Michael A1 - Thiele, Uwe T1 - Long-wave theory of bounded two-layer films with a free liquid-liquid interface: Short and long-time evolution Y1 - 2005 U6 - https://doi.org/10.1063/1.1935487 ER - TY - JOUR A1 - Pototsky, Andrey A1 - Bestehorn, Michael A1 - Merkt, Domnic A1 - Thiele, Uwe T1 - Evolution of interface patterns of three-dimensional two-layer liquid films JF - Europhysics Letters Y1 - 2006 U6 - https://doi.org/10.1209/epl/i2006-10026-8 SN - 0302-072X VL - 74 IS - 4 SP - 665 EP - 671 ER - TY - JOUR A1 - Bestehorn, Michael A1 - Merkt, Domnic T1 - Regular surface patterns on Rayleigh-Taylor unstable evaporating films heated from below Y1 - 2006 ER - TY - JOUR A1 - Borcia, Ion-Dan A1 - Borcia, Rodica A1 - Bestehorn, Michael T1 - Long wave instabilities in binary mixture thin liquid films Y1 - 2006 ER - TY - JOUR A1 - Borcia, Ion-Dan A1 - Borcia, Rodica A1 - Bestehorn, Michael T1 - Soret effect in thin liquid films:Localized running drops, holes and stripes Y1 - 2006 ER - TY - GEN A1 - Bestehorn, Michael A1 - Borcia, Ion-Dan T1 - Thin film lubrication dynamics of a binarymixture Y1 - 2010 ER - TY - JOUR A1 - Enculescu, Mihaela A1 - Bestehorn, Michael T1 - Activity dynamics in non - localinteracting neural fields Y1 - 2003 ER - TY - JOUR A1 - Hutt, A. A1 - Bestehorn, Michael A1 - Wennekers, T. T1 - Pattern Formation in Intracortical Neuronal Fields Y1 - 2003 ER - TY - JOUR A1 - Pena, B. A1 - Pérez-García, C. A1 - Bestehorn, Michael T1 - Modulated standing waves resulting from a Hopf-wave interaction in a chemical model Y1 - 2004 ER - TY - JOUR A1 - Enculescu, Mihaela A1 - Bestehorn, Michael T1 - Liapunov functional for a delayedintegro-differential equation model of a neural field Y1 - 2007 ER - TY - JOUR A1 - Pena, B. A1 - Bestehorn, Michael T1 - Two-dimensional wave patterns near a Hopf-wave interaction in a chemical model Y1 - 2007 ER - TY - JOUR A1 - Enculescu, Mihaela A1 - Bestehorn, Michael T1 - Mechanisms for activity spread in a neural field model Y1 - 2007 ER - TY - GEN A1 - Borcia, Rodica A1 - Bestehorn, Michael T1 - On the coalescence of sessile drops with miscible liquids T2 - European Physical Journal E Y1 - 2011 SN - 1292-8941 VL - 34 IS - 8 SP - 81 ER - TY - GEN A1 - Borcia, Rodica A1 - Menzel, Stefan A1 - Bestehorn, Michael A1 - Karpitschka, Stefan A1 - Riegler, Horst T1 - Delayed coalescence of droplets with miscible liquids: Lubrication and phasefield theories T2 - European Physical Journal E Y1 - 2011 SN - 1292-8941 VL - 34 IS - 3 SP - 11024-9 ER - TY - GEN A1 - Reif, Jürgen A1 - Varlamova, Olga A1 - Varlamov, Sergej A1 - Bestehorn, Michael T1 - The role of asymmetric excitation in self-organized nanostructure formation upon femtosecond laser ablation T2 - Applied Physics / A Y1 - 2011 SN - 1432-0630 VL - 104 IS - 3 SP - 969 EP - 973 ER - TY - GEN A1 - Varlamova, Olga A1 - Reif, Jürgen A1 - Varlamov, Sergej A1 - Bestehorn, Michael T1 - The laser polarization as control parameter in the formation of laser-induced periodic surface structures: Comparison of numerical and experimental results T2 - Applied Surface Science Y1 - 2011 SN - 0169-4332 VL - 257 IS - 12 SP - 5465 EP - 5469 ER - TY - GEN A1 - Borcia, Rodica A1 - Bestehorn, Michael T1 - Numerical simulations on delayed coalescence of droplets in confinedgeometries Y1 - 2010 ER - TY - GEN A1 - Borcia, Ion-Dan A1 - Bestehorn, Michael T1 - Simulation of pattern morphology in binary liquid mixtures Y1 - 2010 ER - TY - CHAP A1 - Borcia, Rodica A1 - Bestehorn, Michael A1 - Egbers, Christoph T1 - Surface effects at the mixing of two perfectly miscible components in a thin liquid film T2 - International Topical Team Workshop on Two-Phase Systems for Ground and Space Applications, ITTW 2013 Y1 - 2013 UR - http://www.zarm.uni-bremen.de/ITTW2013/abstracts/ITTW2013_Book-of-Abstracts.pdf ER - TY - CHAP A1 - Borcia, Ion-Dan A1 - Borcia, Rodica A1 - Bestehorn, Michael A1 - Egbers, Christoph T1 - Drops on cylindrical wires T2 - International Topical Team Workshop on Two-Phase Systems for Ground and Space Applications, ITTW 2013 Y1 - 2013 UR - http://www.zarm.uni-bremen.de/ITTW2013/abstracts/ITTW2013_Book-of-Abstracts.pdf ER - 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 - CHAP A1 - Reif, Jürgen A1 - Varlamova, Olga A1 - Varlamov, Sergej A1 - Bestehorn, Michael ED - Phipps, Claude R. T1 - The role of asymmetric excitation in self-organized nanostructure formation upon femtosecondlaser ablation T2 - International Symposium on High Power Laser Ablation 2012, Santa Fe, New Mexico, USA, 30 April - 3 May 2012 Y1 - 2012 SN - 978-0-7354-1068-8 SP - 428 EP - 441 PB - American Institute of Physics CY - Melville, NY ER - TY - GEN A1 - Varlamova, Olga A1 - Reif, Jürgen A1 - Varlamov, Sergej A1 - Bestehorn, Michael T1 - Modeling of the Laser Polarization as Control Parameter in Self-Organized Surface Pattern T2 - Journal of Nanoscience and Nanotechnology Y1 - 2011 SN - 1533-4880 VL - 11 IS - 10 SP - 9274 EP - 9281 ER - TY - GEN A1 - Varlamova, Olga A1 - Costache, Florenta Adriana A1 - Reif, Jürgen A1 - Bestehorn, Michael T1 - Self-organized pattern formation upon femtosecond laser ablation by circular polarized light T2 - Applied Surface Science Y1 - 2006 SN - 0169-4332 VL - 252 IS - 13 SP - 4702 EP - 4706 ER - TY - CHAP A1 - Reif, Jürgen A1 - Costache, Florenta Adriana A1 - Eckert, Sebastian A1 - Kouteva-Arguirova, Simona A1 - Bestehorn, Michael A1 - Georgescu, Ionut A1 - Semorek, A. F. A1 - Martin, P. A1 - Gobert, O. A1 - Seifert, Winfried T1 - Formation of self-organized regular nanostructures upon femtosecond laser ablation T2 - Fifth International Symposium on Laser Precision Microfabrication, 11 - 14 May, 2004, Nara, Japan Y1 - 2004 SN - 0-8194-5623-3 SP - S. 737 PB - SPIE CY - Bellingham, Wash. ER - TY - CHAP A1 - Varlamova, Olga A1 - Reif, Jürgen A1 - Varlamov, Sergej A1 - Bestehorn, Michael ED - Sakabe, Shuji ED - Lienau, Christoph ED - Grunwald, Rüdiger T1 - Self-organized Surface Patterns Originatin from Laser-Induced Instability T2 - Progress in nonlinear nano-optics Y1 - 2015 SN - 978-3-319-12216-8 SN - 3-319-12216-9 SP - 3 EP - 29 PB - Springer CY - Cham [u.a.] ER - TY - GEN A1 - Cheng, Philip A1 - Bestehorn, Michael A1 - Firoozabadi, Abbas T1 - Effect of permeability anisotropy on density-driven flow for CO2 sequestration in saline aquifers T2 - Water Resources Research N2 - Solubility trapping of carbon dioxide (CO2) in deep saline aquifers is considered one of the most effective methods for carbon sequestration. Dissolution of CO2 into the brine may create gravitational instabilities that lead to the onset of convection, which greatly enhances the storage efficiency and reduces the possibilities of leakage. Convection appears in the form of downward traveling fingers of relatively dense, CO2-dissolved fluid. Many natural aquifer formations display considerable permeability anisotropy, where the horizontal permeability kh may be several times greater than the vertical permeability kz. It has been previously found that increasing kh for a fixed kz reduces the critical time tc at which onset occurs and the critical wavelength λc with which the fingers initially form. We extend earlier work by showing how and why this occurs. Our results reveal new insights about λc. We have studied the behavior for times greater than tc using high-resolution numerical simulations. We show that the enhanced dissolution from convection can become significant much earlier in anisotropic media. Furthermore, the effects of anisotropy may be sustained for a long period of time. Our results suggest that permeability anisotropy can allow a wider range of aquifer formations to be considered for effective sequestration. Y1 - 2012 UR - http://onlinelibrary.wiley.com/doi/10.1029/2012WR011939/abstract U6 - https://doi.org/10.1029/2012WR011939 SN - 1944-7973 VL - 48 IS - 9 SP - W09539 ER - TY - GEN A1 - Bestehorn, Michael A1 - Firoozabadi, Abbas T1 - Effect of fluctuations on the onset of density-driven convection in porous media T2 - Physics of Fluids N2 - We study the dissolution of CO2 in saline aquifers. The long diffusion times can be accelerated by orders of magnitude from mass transfer that origins from convection.Convection occurs at a critical time via a phase transition from the horizontally homogeneous diffusion state. To start the instability, perturbations that break the horizontal translation symmetry are necessary. We start with the basic equations and the boundary conditions, examine the linearized equations around the diffusive time and z-dependent base state and compare different definitions of the critical time found in the literature. Taking a simple model we show the role of fluctuations for delayed instabilities if the control parameter is slowly swept through the bifurcation point. Apart from the critical time we use a “visible” time where convection is manifested in the vertical CO2 transport. We specify the perturbations with respect to their strength and length scale, and compute the critical times for various cases by numerical integration of the basic equations in two spatial dimensions. Fluctuating concentration at the upper boundary, fluctuating porosity as well fluctuating permeability are studied in detail. For the permeability fluctuation, the compressibility of the fluid becomes important and the velocity field cannot be derived from a stream function. Our work also includes non-isothermal conditions with a prescribed vertical geothermal gradient and space dependent thermal conductivity. Temperature fields for different standard configurations are computed numerically and serve as starting condition for density-driven convection. Based on our work, we conclude that the visible time is much larger than the critical time. The visible time is a strong function of strength and length scale of the perturbations. Y1 - 2012 UR - http://scitation.aip.org/content/aip/journal/pof2/24/11/10.1063/1.4767467 U6 - https://doi.org/10.1063/1.4767467 SN - 1089-7666 VL - 24 IS - 11 SP - 114102 ER - TY - GEN A1 - Reif, Jürgen A1 - Varlamova, Olga A1 - Uhlig, Sebastian A1 - Varlamov, Sergej A1 - Bestehorn, Michael T1 - On the physics of self-organized nanostructure formation upon femtosecond laser ablation T2 - Applied Physics A N2 - We present new results on femtosecond LIPSS on silicon, fostering the dynamic model of self-organized structure formation. The first set of experiments demonstrates LIPSS formation by irradiation with a femtosecond white light continuum. The ripples are, as usual, perpendicular to the light polarization with a fluence-dependent wavelength between 500 and 700 nm. At higher dose (fluence × number of shots), the LIPSS turn to much coarser structures. The second set of experiments displays the dose dependence of pattern evolution at about threshold fluence. In contrast to the general case of multi-pulse LIPSS, where a strong dependence of the structures on the laser polarization is observed, single-shot exposition of silicon at about the ablation threshold results in a concentric pattern of very regular sub-wavelength ripples following the oval shape of the irradiated spot, without any reference to the laser polarization. When increasing the number of pulses, the usual, typical ripples develop and then coalesce into broader perpendicular structures, interlaced with remnants of the first, finer ripples. Y1 - 2014 UR - http://link.springer.com/article/10.1007/s00339-014-8339-x U6 - https://doi.org/10.1007/s00339-014-8339-x SN - 0947-8396 SN - 1432-0630 VL - 117 IS - 1 SP - 179 EP - 184 ER - TY - GEN A1 - Bestehorn, Michael T1 - Laterally Extended Thin Liquid Films with inertia Under External Vibrations T2 - Physics of Fluids N2 - We consider thin liquid films on a horizontal, solid, and completely wetting substrate. The substrate is subjected to oscillatory accelerations in the normal direction and/or in the horizontal direction. A linear Floquet analysis shows that the planar film surface loses stability if amplitudes and frequencies of the harmonic oscillations meet certain criteria. Based on the long wave lubrication approximation, we present an integral boundary layer model where the z component is integrated out and the spatial dimension is reduced by one. The linear stability analysis of this model shows good agreement with the exact problem and with the linearized long wave equations. Pattern formation in the nonlinear regime is computed numerically from the long wave model in two and three spatial dimensions. Normal oscillations show the traditional Faraday patterns such as squares and hexagons. Lateral oscillations cause a pattern formation scenario similar to spinodal dewetting, namely coarsening and no rupture. For certain amplitude and frequency ranges, combined lateral and normal oscillations can give rise to one or more traveling drops. Finally, we discuss the control of a drop's motion in the horizontal plane. KW - Lubrication KW - Coarsening KW - Pattern formation KW - Boundary value problems KW - Van der Waals forces Y1 - 2013 UR - http://scitation.aip.org/content/aip/journal/pof2/25/11/10.1063/1.4830255 U6 - https://doi.org/10.1063/1.4830255 SN - 1089-7666 VL - 25 IS - 11 SP - 114106 ER - TY - GEN A1 - Bestehorn, Michael A1 - Han, Qi A1 - Oron, Alexander T1 - Nonlinear Pattern Formation in Thin Liqiud Films Under External Vibrations T2 - Physical Review E N2 - We study a thin liquid film with a free surface on a planar horizontal substrate. The substrate is subjected to oscillatory accelerations in the normal and/or in the horizontal direction(s). The description is based on the longwave approximation including inertia effects, which are important due to the large velocities imparted by external vibrations. The linearized system is examined using the Floquet analysis. Pattern formation in the nonlinear regime is computed numerically from the longwave equations for the thickness and the flow rate of the fluid in two and in three spatial dimensions. For certain amplitude and frequency ranges, combined lateral and normal oscillations can give rise to one or more traveling drops, similar to recent experimental findings by Brunet et al. [Phys. Rev. Lett. 99, 144501 (2007)]. Y1 - 2013 UR - http://journals.aps.org/pre/abstract/10.1103/PhysRevE.88.023025 U6 - https://doi.org/10.1103/PhysRevE.88.023025 SN - 2470-0053 VL - 88 IS - 2 SP - 023025 ER - TY - GEN A1 - Bestehorn, Michael T1 - Regular Hexagons and Stripes on Marangoni and Rayleigh-Taylor unstable volatile thin films T2 - European Journal of Mechanics - B/Fluids N2 - Thin volatile Newtonian liquid films with a free surface on a cooled horizontal substrate are studied theoretically and numerically. We show that if the fluid is initially in equilibrium with its own vapor in the gas phase, regular surface deformation patterns in the form of long-wave hexagons or stripes having a well defined lateral length scale are observed, depending on the instability mechanism. This is different to the case without evaporation where rupture or coarsening to larger and larger spatially disordered patterns is seen in the long time limit. We propose to use such a system to create a regular structuring of the film’s surface. Heat production by latent heat and the influence of a temperature dependent surface tension (Marangoni effect) are included as well. Special emphasis is laid on the so-called anomalous Marangoni effect. In this case a parameter region where stripes should occur already at threshold is found by means of a systematic weakly non-linear analysis. KW - Thin films KW - Rayleigh–Taylor instability KW - Marangoni effect KW - Convection KW - Evaporation KW - Pattern formation Y1 - 2014 UR - http://www.sciencedirect.com/science/article/pii/S0997754613001477 U6 - https://doi.org/10.1016/j.euromechflu.2013.12.005 VL - 47 SP - 48 EP - 56 ER -