Ulrich, Stephan

[["dc.bibliographiccitation.artnumber","166001"],["dc.bibliographiccitation.issue","16"],["dc.bibliographiccitation.journal","Physical Review Letters"],["dc.bibliographiccitation.volume","109"],["dc.contributor.author","Ulrich, Stephan"],["dc.contributor.author","Zippelius, Annette"],["dc.date.accessioned","2018-11-07T09:04:32Z"],["dc.date.available","2018-11-07T09:04:32Z"],["dc.date.issued","2012"],["dc.description.abstract","A freely falling stream of weakly cohesive granular particles is modeled and analyzed with the help of event driven simulations and continuum hydrodynamics. The former show a breakup of the stream into droplets, whose size is measured as a function of cohesive energy. Extensional flow is an exact solution of the one-dimensional Navier-Stokes equation, corresponding to a strain rate, decaying like t(-1) from its initial value, (gamma)over dot(0). Expanding around this basic state, we show that the flow is stable for short times, (gamma)over dot(0)t << 1, whereas for long times, (gamma)over dot(0)t >> 1, perturbations of all wavelengths grow. The growth rate of a given wavelength depends on the instant of time when the fluctuation occurs, so that the observable patterns can vary considerably."],["dc.identifier.doi","10.1103/PhysRevLett.109.166001"],["dc.identifier.isi","000310004300007"],["dc.identifier.pmid","23215093"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/25128"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Physical Soc"],["dc.relation.issn","0031-9007"],["dc.title","Stability of Freely Falling Granular Streams"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","115011"],["dc.bibliographiccitation.journal","New Journal of Physics"],["dc.bibliographiccitation.volume","14"],["dc.contributor.author","Benetatos, Panayotis"],["dc.contributor.author","Ulrich, Stephan"],["dc.contributor.author","Zippelius, Annette"],["dc.date.accessioned","2018-11-07T09:03:17Z"],["dc.date.available","2018-11-07T09:03:17Z"],["dc.date.issued","2012"],["dc.description.abstract","Cross-linked polymer networks with orientational order constitute a wide class of soft materials and are relevant to biological systems (e. g., F-actin bundles). We analytically study the nonlinear force-extension relation of an array of parallel-aligned, strongly stretched semiflexible polymers with random cross-links. In the strong stretching limit, the effect of the cross-links is purely entropic, independent of the bending rigidity of the chains. Cross-links enhance the differential stretching stiffness of the bundle. For hard cross-links, the cross-link contribution to the force-extension relation scales inversely proportional to the force. Its dependence on the cross-link density, close to the gelation transition, is the same as that of the shear modulus. The qualitative behaviour is captured by a toy model of two chains with a single cross-link in the middle."],["dc.description.sponsorship","DFG [SFB 937]; EPSRC via the University of Cambridge TCM Programme Grant"],["dc.identifier.doi","10.1088/1367-2630/14/11/115011"],["dc.identifier.fs","591080"],["dc.identifier.isi","000311581600002"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/10186"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/24877"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Iop Publishing Ltd"],["dc.relation.issn","1367-2630"],["dc.relation.orgunit","Fakultät für Physik"],["dc.rights","CC BY 3.0"],["dc.title","Force-extension relation of cross-linked anisotropic polymer networks"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1"],["dc.bibliographiccitation.issue","14"],["dc.bibliographiccitation.journal","Physical Review Letters"],["dc.bibliographiccitation.lastpage","4"],["dc.bibliographiccitation.volume","102"],["dc.contributor.author","Ulrich, Stephan"],["dc.contributor.author","Aspelmeier, Timo"],["dc.contributor.author","Roeller, Klaus"],["dc.contributor.author","Fingerle, Axel"],["dc.contributor.author","Herminghaus, Stephan"],["dc.contributor.author","Zippelius, Annette"],["dc.date.accessioned","2021-06-01T10:47:05Z"],["dc.date.available","2021-06-01T10:47:05Z"],["dc.date.issued","2009"],["dc.description.abstract","Wet granular materials are characterized by a defined bond energy in their particle interaction such that breaking a bond implies an irreversible loss of a fixed amount of energy. Associated with the bond energy is a nonequilibrium transition, setting in as the granular temperature falls below the bond energy. The subsequent aggregation of particles into clusters is shown to be a self-similar growth process with a cluster size distribution that obeys scaling. In the early phase of aggregation the clusters are fractals with Df=2, for later times we observe gelation. We use simple scaling arguments to derive the temperature decay in the early and late stages of cooling and verify our results with event-driven simulations."],["dc.identifier.doi","10.1103/PhysRevLett.102.148002"],["dc.identifier.gro","3146215"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/85479"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-425"],["dc.notes.status","final"],["dc.relation.eissn","1079-7114"],["dc.relation.issn","0031-9007"],["dc.title","Cooling and Aggregation in Wet Granulates"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","021802"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Physical Review. E"],["dc.bibliographiccitation.volume","81"],["dc.contributor.author","Ulrich, Stephan"],["dc.contributor.author","Zippelius, Annette"],["dc.contributor.author","Benetatos, Panayotis"],["dc.date.accessioned","2018-11-07T08:46:34Z"],["dc.date.available","2018-11-07T08:46:34Z"],["dc.date.issued","2010"],["dc.description.abstract","We explore the effect of random permanent cross-links on a system of directed polymers confined between two planes with their end points free to slide on them. We treat the cross-links as quenched disorder and we use a semimicroscopic replica field theory to study the structure and elasticity of this system. Upon increasing the cross-link density, we get a continuous gelation transition signaled by the emergence of a finite in-plane localization length. The distribution of localization length turns out to depend on the height along the preferred direction of the directed polymers. The gelation transition also gives rise to a finite in-plane shear modulus which we calculate and turns out to be universal, i.e., independent of the energy and length scales of the polymers and the cross-links. Using a symmetry argument, we show that cross-links of negligible extent along the preferred axis of the directed polymers do not cause any renormalization to the tilt modulus of the uncross-linked system."],["dc.description.sponsorship","DFG [SFB 602]; University of Cambridge TCM Programme"],["dc.identifier.doi","10.1103/PhysRevE.81.021802"],["dc.identifier.isi","000275053700074"],["dc.identifier.pmid","20365585"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/20724"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Physical Soc"],["dc.relation.issn","1539-3755"],["dc.title","Random networks of cross-linked directed polymers"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","031306"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Physical Review. E"],["dc.bibliographiccitation.volume","80"],["dc.contributor.author","Ulrich, Stephan"],["dc.contributor.author","Aspelmeier, Timo"],["dc.contributor.author","Zippelius, Annette"],["dc.contributor.author","Roeller, Klaus"],["dc.contributor.author","Fingerle, Axel"],["dc.contributor.author","Herminghaus, Stephan"],["dc.date.accessioned","2018-11-07T11:25:24Z"],["dc.date.available","2018-11-07T11:25:24Z"],["dc.date.issued","2009"],["dc.description.abstract","We investigate a gas of wet granular particles covered by a thin liquid film. The dynamic evolution is governed by two-particle interactions, which are mainly due to interfacial forces in contrast to dry granular gases. When two wet grains collide, a capillary bridge is formed and stays intact up to a certain distance of withdrawal when the bridge ruptures, dissipating a fixed amount of energy. A freely cooling system is shown to undergo a nonequilibrium dynamic phase transition from a state with mainly single particles and fast cooling to a state with growing aggregates such that bridge rupture becomes a rare event and cooling is slow. In the early stage of cluster growth, aggregation is a self-similar process with a fractal dimension of the aggregates approximately equal to D(f) approximate to 2. At later times, a percolating cluster is observed which ultimately absorbs all the particles. The final cluster is compact on large length scales, but fractal with D(f) approximate to 2 on small length scales."],["dc.description.sponsorship","Deutsche Forschungsgemeinschaft (DFG) [SFB 602/B6]"],["dc.identifier.doi","10.1103/PhysRevE.80.031306"],["dc.identifier.isi","000270383400069"],["dc.identifier.pmid","19905109"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/56613"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Physical Soc"],["dc.relation.issn","1539-3755"],["dc.title","Dilute wet granular particles: Nonequilibrium dynamics and structure formation"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]