Bodenschatz, Eberhard

[["dc.bibliographiccitation.firstpage","375"],["dc.bibliographiccitation.journal","Journal of Fluid Mechanics"],["dc.bibliographiccitation.lastpage","385"],["dc.bibliographiccitation.volume","629"],["dc.contributor.author","Ouellette, Nicholas T."],["dc.contributor.author","Xu, H."],["dc.contributor.author","Bodenschatz, Eberhard"],["dc.date.accessioned","2018-11-07T08:28:39Z"],["dc.date.available","2018-11-07T08:28:39Z"],["dc.date.issued","2009"],["dc.description.abstract","By tracking small particles in the bulk of an intensely turbulent laboratory flow, we study the effect of long-chain polymers on the Eulerian structure functions. We find that the structure functions are modified over a wide range or length scales even for very small polymer concentrations. Their behaviour can be captured by defining a length scale that depends on the solvent viscosity, the polymer relaxation time and the Weissenberg number. This result is not captured by Current models. Additionally, the effects we observe depend strongly on the concentration. While the dissipation-range statistics change smoothly as a function of polymer concentration, we find that the inertial-range values of the structure functions are modified only when the concentration exceeds a threshold of approximately 5 parts per million (p.p.m.) by weight for the 18 X 10(6) atomic mass unit (a.m.u.) molecular weight polyacrylamide used in the experiment."],["dc.identifier.doi","10.1017/S0022112009006697"],["dc.identifier.isi","000267770200017"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/16472"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Cambridge Univ Press"],["dc.relation.issn","1469-7645"],["dc.relation.issn","0022-1120"],["dc.title","Bulk turbulence in dilute polymer solutions"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","2095"],["dc.bibliographiccitation.issue","14-17"],["dc.bibliographiccitation.journal","Physica D Nonlinear Phenomena"],["dc.bibliographiccitation.lastpage","2100"],["dc.bibliographiccitation.volume","237"],["dc.contributor.author","Xu, H."],["dc.contributor.author","Bodenschatz, Eberhard"],["dc.date.accessioned","2018-11-07T11:12:09Z"],["dc.date.available","2018-11-07T11:12:09Z"],["dc.date.issued","2008"],["dc.description.abstract","We report experimental results on the motion of tracer and non-tracer particles in intense turbulent water flows between counter-rotating disks measured by three-dimensional Lagrangian particle tracking. The sizes of the non-tracer particles were in the range of eta < d(p) << L, where eta is the Kolmogorov length scale and L is the integral scale. We propose a modified Stokes number that takes into account the effects from finite particle size and inertia. We compare results from tracers and from two types of particles (heavy+small, approx. neutrally bouyant+large) for which the conventional Stokes numbers differ by a factor of approximate to 8% and the modified Stokes numbers by approximate to 60%. The conventional Stokes numbers of the particles investigated were in the range of 0.7 and 1.5, while the modified Stokes numbers were smaller between 0.1 to 0.3. We observed that the tails of the measured acceleration PDFs were slightly narrower compared to tracer particles with the heavier+smaller particles showing a larger effect. The measured Lagrangian acceleration correlations of the large particles were approximately the same as that of the tracer particles. This suggests that trajectories of large particles are not biased towards the low-vorticity, high-straining region as was observed previously in the case of small, very heavy particles. These findings are also supported by the measurements of the local slopes of the fourth order Lagrangian structure functions. (c) 2008 Elsevier B.V. All rights reserved."],["dc.description.sponsorship","Max Planck Society [PHY-9988755]; NSF [PHY-0216406]"],["dc.identifier.doi","10.1016/j.physd.2008.04.022"],["dc.identifier.isi","000258508000039"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/53599"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Elsevier Science Bv"],["dc.relation.issn","1872-8022"],["dc.relation.issn","0167-2789"],["dc.title","Motion of inertial particles with size larger than Kolmogorov scale in turbulent flows"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","64005"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","EPL (Europhysics Letters)"],["dc.bibliographiccitation.volume","90"],["dc.contributor.author","Gibert, Mathieu"],["dc.contributor.author","Xu, H."],["dc.contributor.author","Bodenschatz, Eberhard"],["dc.date.accessioned","2018-11-07T08:42:33Z"],["dc.date.available","2018-11-07T08:42:33Z"],["dc.date.issued","2010"],["dc.description.abstract","We report experimental results on the relative motion of pairs of solid spheric particles with initial separations in the inertial range of fully developed turbulence in water. The particle densities were in the range of 1 approximate to rho(p)/rho f approximate to 8, i.e., from neutrally buoyant to highly inertial; and their sizes were of the Kolmogorov scale. For all particles, we observed a Batchelor-like regime, in which particles separated ballistically. Similar to the Batchelor regime for tracers, this regime was observed in the early stages of the relative separation for times t similar to 0.1t(0) with t(0) determined by the turbulence energy dissipation rate and the initial separation between particle pairs. In this time interval heavier particles separated faster than fluid tracers. The second-order Eulerian velocity structure functions was found to increase with density. In other words, both observations show that the relative velocity between inertial particles was larger than that between tracers. Based on the widely used, simplified equation of motion for inertial point-particles, we derived a model that shows an increase in relative velocity between inertial particles. In its scale dependence, however, it disagrees quantitatively with the experimental results. This we attribute to the preferential sampling of the flow field by inertial particles, which is not captured by the model."],["dc.description.sponsorship","Max Planck Society; Marie Curie Fellowship [FP7-PEOPLE-IEF-2008, 237521]"],["dc.identifier.doi","10.1209/0295-5075/90/64005"],["dc.identifier.isi","000282852900013"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/19727"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Epl Association, European Physical Society"],["dc.relation.issn","1286-4854"],["dc.relation.issn","0295-5075"],["dc.title","Inertial effects on two-particle relative dispersion in turbulent flows"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","035101"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Physics of Fluids"],["dc.bibliographiccitation.volume","25"],["dc.contributor.author","Pumir, Alain"],["dc.contributor.author","Bodenschatz, Eberhard"],["dc.contributor.author","Xu, H."],["dc.date.accessioned","2018-11-07T09:27:15Z"],["dc.date.available","2018-11-07T09:27:15Z"],["dc.date.issued","2013"],["dc.description.abstract","We describe the structure and dynamics of turbulence by the scale-dependent perceived velocity gradient tensor as supported by following four tracers, i.e., fluid particles, that initially form a regular tetrahedron. We report results from experiments in a von Kaacutermaacuten swirling water flow and from numerical simulations of the incompressible Navier-Stokes equation. We analyze the statistics and the dynamics of the perceived rate of strain tensor and vorticity for initially regular tetrahedron of size r0 from the dissipative to the integral scale. Just as for the true velocity gradient, at any instant, the perceived vorticity is also preferentially aligned with the intermediate eigenvector of the perceived rate of strain. However, in the perceived rate of strain eigenframe fixed at a given time t = 0, the perceived vorticity evolves in time such as to align with the strongest eigendirection at t = 0. This also applies to the true velocity gradient. The experimental data at the higher Reynolds number suggests the existence of a self-similar regime in the inertial range. In particular, the dynamics of alignment of the perceived vorticity and strain can be rescaled by t0, the turbulence time scale of the flow when the scale r0 is in the inertial range. For smaller Reynolds numbers we found the dynamics to be scale dependent."],["dc.identifier.doi","10.1063/1.4795547"],["dc.identifier.isi","000316951900026"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/30492"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Inst Physics"],["dc.relation.issn","1070-6631"],["dc.title","Tetrahedron deformation and alignment of perceived vorticity and strain in a turbulent flow"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","3219"],["dc.bibliographiccitation.issue","8"],["dc.bibliographiccitation.journal","Atmospheric Measurement Techniques"],["dc.bibliographiccitation.lastpage","3228"],["dc.bibliographiccitation.volume","8"],["dc.contributor.author","Siebert, H."],["dc.contributor.author","Shaw, R. A."],["dc.contributor.author","Ditas, J."],["dc.contributor.author","Schmeissner, T."],["dc.contributor.author","Malinowski, S. P."],["dc.contributor.author","Bodenschatz, E."],["dc.contributor.author","Xu, H."],["dc.date.accessioned","2022-06-08T07:57:37Z"],["dc.date.available","2022-06-08T07:57:37Z"],["dc.date.issued","2015"],["dc.description.abstract","Abstract. Mountain research stations are advantageous not only for long-term sampling of cloud properties but also for measurements that are prohibitively difficult to perform on airborne platforms due to the large true air speed or adverse factors such as weight and complexity of the equipment necessary. Some cloud–turbulence measurements, especially Lagrangian in nature, fall into this category. We report results from simultaneous, high-resolution and collocated measurements of cloud microphysical and turbulence properties during several warm cloud events at the Umweltforschungsstation Schneefernerhaus (UFS) on Zugspitze in the German Alps. The data gathered were found to be representative of observations made with similar instrumentation in free clouds. The observed turbulence shared all features known for high-Reynolds-number flows: it exhibited approximately Gaussian fluctuations for all three velocity components, a clearly defined inertial subrange following Kolmogorov scaling (power spectrum, and second- and third-order Eulerian structure functions), and highly intermittent velocity gradients, as well as approximately lognormal kinetic energy dissipation rates. The clouds were observed to have liquid water contents on the order of 1 g m−3 and size distributions typical of continental clouds, sometimes exhibiting long positive tails indicative of large drop production through turbulent mixing or coalescence growth. Dimensionless parameters relevant to cloud–turbulence interactions, the Stokes number and settling parameter are in the range typically observed in atmospheric clouds. Observed fluctuations in droplet number concentration and diameter suggest a preference for inhomogeneous mixing. Finally, enhanced variance in liquid water content fluctuations is observed at high frequencies, and the scale break occurs at a value consistent with the independently estimated phase relaxation time from microphysical measurements."],["dc.identifier.doi","10.5194/amt-8-3219-2015"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/110152"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-575"],["dc.relation.eissn","1867-8548"],["dc.title","High-resolution measurement of cloud microphysics and turbulence at a mountaintop station"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","079901"],["dc.bibliographiccitation.issue","7"],["dc.bibliographiccitation.journal","Physics of Fluids"],["dc.bibliographiccitation.volume","24"],["dc.contributor.author","Falkovich, Gregory"],["dc.contributor.author","Xu, H."],["dc.contributor.author","Pumir, Alain"],["dc.contributor.author","Bodenschatz, Eberhard"],["dc.contributor.author","Biferale, Luca"],["dc.contributor.author","Boffetta, Guido"],["dc.contributor.author","Lanotte, Alessandra S."],["dc.contributor.author","Toschi, Federico"],["dc.date.accessioned","2018-11-07T09:08:22Z"],["dc.date.available","2018-11-07T09:08:22Z"],["dc.date.issued","2012"],["dc.identifier.doi","10.1063/1.4738734"],["dc.identifier.isi","000308406000055"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/26017"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Inst Physics"],["dc.relation.issn","1070-6631"],["dc.title","On Lagrangian single-particle statistics (vol 24, 055102, 2012)"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","041006"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Physical Review X"],["dc.bibliographiccitation.volume","4"],["dc.contributor.author","Pumir, Alain"],["dc.contributor.author","Xu, H."],["dc.contributor.author","Boffetta, Guido"],["dc.contributor.author","Falkovich, Gregory"],["dc.contributor.author","Bodenschatz, Eberhard"],["dc.date.accessioned","2018-11-07T09:33:40Z"],["dc.date.available","2018-11-07T09:33:40Z"],["dc.date.issued","2014"],["dc.description.abstract","In statistically homogeneous turbulent flows, pressure forces provide the main mechanism to redistribute kinetic energy among fluid elements, without net contribution to the overall energy budget. This holds true in both two-dimensional (2D) and three-dimensional (3D) flows, which show fundamentally different physics. As we demonstrate here, pressure forces act on fluid elements very differently in these two cases. We find in numerical simulations that in 3D pressure forces strongly accelerate the fastest fluid elements, and that in 2D this effect is absent. In 3D turbulence, our findings put forward a mechanism for a possibly singular buildup of energy, and thus may shed new light on the smoothness problem of the solution of the Navier-Stokes equation in 3D."],["dc.identifier.doi","10.1103/PhysRevX.4.041006"],["dc.identifier.fs","606696"],["dc.identifier.isi","000343773800001"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/11554"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/32019"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Physical Soc"],["dc.relation","info:eu-repo/grantAgreement/EC/FP7/312778/EU//EUHIT"],["dc.relation.issn","2160-3308"],["dc.relation.orgunit","Fakultät für Physik"],["dc.rights","CC BY 3.0"],["dc.title","Redistribution of Kinetic Energy in Turbulent Flows"],["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","065103"],["dc.bibliographiccitation.issue","6"],["dc.bibliographiccitation.journal","Physics of Fluids"],["dc.bibliographiccitation.volume","20"],["dc.contributor.author","Biferale, L."],["dc.contributor.author","Bodenschatz, E."],["dc.contributor.author","Cencini, M."],["dc.contributor.author","Lanotte, A. S."],["dc.contributor.author","Ouellette, N. T."],["dc.contributor.author","Toschi, F."],["dc.contributor.author","Xu, H."],["dc.date.accessioned","2022-06-08T07:58:51Z"],["dc.date.available","2022-06-08T07:58:51Z"],["dc.date.issued","2008"],["dc.identifier.doi","10.1063/1.2930672"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/110551"],["dc.language.iso","en"],["dc.notes.intern","DOI-Import GROB-575"],["dc.relation.eissn","1089-7666"],["dc.relation.issn","1070-6631"],["dc.title","Lagrangian structure functions in turbulence: A quantitative comparison between experiment and direct numerical simulation"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","709"],["dc.bibliographiccitation.issue","9"],["dc.bibliographiccitation.journal","Nature Physics"],["dc.bibliographiccitation.lastpage","712"],["dc.bibliographiccitation.volume","7"],["dc.contributor.author","Xu, H."],["dc.contributor.author","Pumir, Alain"],["dc.contributor.author","Bodenschatz, Eberhard"],["dc.date.accessioned","2018-11-07T08:52:45Z"],["dc.date.available","2018-11-07T08:52:45Z"],["dc.date.issued","2011"],["dc.description.abstract","The disorganized fluctuations of turbulence are crucial in the transport of particles or chemicals(1,2) and could play a decisive role in the formation of rain in clouds(3), the accretion process in protoplanetary disks(4), and how animals find their mates or prey(5,6). These and other examples(7) suggest a yet-to-be-determined unifying structure of turbulent flows(8,9). Here, we unveil an important ingredient of turbulence by taking the perspective of an observer who perceives its world with respect to three distant neighbours all swept by the flow. The time evolution of the observer's world can be decomposed into rotation and stretching. We show that, in this Lagrangian frame, the axis of rotation aligns with the initially strongest stretching direction, and that the dynamics can be understood by the conservation of angular momentum. This 'pirouette effect' thus appears as an important structural component of turbulence, and elucidates the mechanism for small-scale generation in turbulence."],["dc.identifier.doi","10.1038/NPHYS2010"],["dc.identifier.isi","000294485400018"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/22245"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Nature Publishing Group"],["dc.relation.issn","1745-2473"],["dc.title","The pirouette effect in turbulent flows"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","055102"],["dc.bibliographiccitation.issue","5"],["dc.bibliographiccitation.journal","Physics of Fluids"],["dc.bibliographiccitation.volume","24"],["dc.contributor.author","Falkovich, Gregory"],["dc.contributor.author","Xu, H."],["dc.contributor.author","Pumir, Alain"],["dc.contributor.author","Bodenschatz, Eberhard"],["dc.contributor.author","Biferale, Luca"],["dc.contributor.author","Boffetta, Guido"],["dc.contributor.author","Lanotte, Alessandra S."],["dc.contributor.author","Toschi, Federico"],["dc.date.accessioned","2018-11-07T09:10:36Z"],["dc.date.available","2018-11-07T09:10:36Z"],["dc.date.issued","2012"],["dc.description.abstract","In turbulence, ideas of energy cascade and energy flux, substantiated by the exact Kolmogorov relation, lead to the determination of scaling laws for the velocity spatial correlation function. Here we ask whether similar ideas can be applied to temporal correlations. We critically review the relevant theoretical and experimental results concerning the velocity statistics of a single fluid particle in the inertial range of statistically homogeneous, stationary and isotropic turbulence. We stress that the widely used relations for the second structure function, D-2(t) equivalent to <[nu(t) - nu(0)](2)> proportional to epsilon t, relies on dimensional arguments only: no relation of D-2(t) to the energy cascade is known, neither in two- nor in three-dimensional turbulence. State of the art experimental and numerical results demonstrate that at high Reynolds numbers, the derivative dD(2)(t)/dt has a finite non-zero slope starting from t approximate to 2 tau(eta). The analysis of the acceleration spectrum Phi(A)(omega) indicates a possible small correction with respect to the dimensional expectation Phi(A)(omega) similar to omega(0) but present data are unable to discriminate between anomalous scaling and finite Reynolds effects in the second order moment of velocity Lagrangian statistics. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4711397]"],["dc.description.sponsorship","US National Science Foundation [NSF PHY05-51164]"],["dc.identifier.doi","10.1063/1.4711397"],["dc.identifier.isi","000304826100028"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/26528"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Amer Inst Physics"],["dc.relation.issn","1089-7666"],["dc.relation.issn","1070-6631"],["dc.title","On Lagrangian single-particle statistics"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]