--- _id: '5943' abstract: - lang: eng text: The hairpin instability of a jet in a crossflow (JICF) for a low jet-to-crossflow velocity ratio is investigated experimentally for a velocity ratio range of R ∈ (0.14, 0.75) and crossflow Reynolds numbers ReD ∈ (260, 640). From spectral analysis we characterize the Strouhal number and amplitude of the hairpin instability as a function of R and ReD. We demonstrate that the dynamics of the hairpins is well described by the Landau model, and, hence, that the instability occurs through Hopf bifurcation, similarly to other hydrodynamical oscillators such as wake behind different bluff bodies. Using the Landau model, we determine the precise threshold values of hairpin shedding. We also study the spatial dependence of this hydrodynamical instability, which shows a global behaviour. article_processing_charge: No article_type: original author: - first_name: Lukasz full_name: Klotz, Lukasz id: 2C9AF1C2-F248-11E8-B48F-1D18A9856A87 last_name: Klotz orcid: 0000-0003-1740-7635 - first_name: Konrad full_name: Gumowski, Konrad last_name: Gumowski - first_name: José Eduardo full_name: Wesfreid, José Eduardo last_name: Wesfreid citation: ama: Klotz L, Gumowski K, Wesfreid JE. Experiments on a jet in a crossflow in the low-velocity-ratio regime. Journal of Fluid Mechanics. 2019;863:386-406. doi:10.1017/jfm.2018.974 apa: Klotz, L., Gumowski, K., & Wesfreid, J. E. (2019). Experiments on a jet in a crossflow in the low-velocity-ratio regime. Journal of Fluid Mechanics. Cambridge University Press. https://doi.org/10.1017/jfm.2018.974 chicago: Klotz, Lukasz, Konrad Gumowski, and José Eduardo Wesfreid. “Experiments on a Jet in a Crossflow in the Low-Velocity-Ratio Regime.” Journal of Fluid Mechanics. Cambridge University Press, 2019. https://doi.org/10.1017/jfm.2018.974. ieee: L. Klotz, K. Gumowski, and J. E. Wesfreid, “Experiments on a jet in a crossflow in the low-velocity-ratio regime,” Journal of Fluid Mechanics, vol. 863. Cambridge University Press, pp. 386–406, 2019. ista: Klotz L, Gumowski K, Wesfreid JE. 2019. Experiments on a jet in a crossflow in the low-velocity-ratio regime. Journal of Fluid Mechanics. 863, 386–406. mla: Klotz, Lukasz, et al. “Experiments on a Jet in a Crossflow in the Low-Velocity-Ratio Regime.” Journal of Fluid Mechanics, vol. 863, Cambridge University Press, 2019, pp. 386–406, doi:10.1017/jfm.2018.974. short: L. Klotz, K. Gumowski, J.E. Wesfreid, Journal of Fluid Mechanics 863 (2019) 386–406. date_created: 2019-02-10T22:59:15Z date_published: 2019-03-25T00:00:00Z date_updated: 2023-08-24T14:43:13Z day: '25' department: - _id: BjHo doi: 10.1017/jfm.2018.974 ec_funded: 1 external_id: arxiv: - '1902.07931' isi: - '000526029100016' intvolume: ' 863' isi: 1 language: - iso: eng main_file_link: - open_access: '1' url: https://arxiv.org/abs/1902.07931 month: '03' oa: 1 oa_version: Preprint page: 386-406 project: - _id: 260C2330-B435-11E9-9278-68D0E5697425 call_identifier: H2020 grant_number: '754411' name: ISTplus - Postdoctoral Fellowships publication: Journal of Fluid Mechanics publication_status: published publisher: Cambridge University Press quality_controlled: '1' scopus_import: '1' status: public title: Experiments on a jet in a crossflow in the low-velocity-ratio regime type: journal_article user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8 volume: 863 year: '2019' ... --- _id: '5878' abstract: - lang: eng text: We consider the motion of a droplet bouncing on a vibrating bath of the same fluid in the presence of a central potential. We formulate a rotation symmetry-reduced description of this system, which allows for the straightforward application of dynamical systems theory tools. As an illustration of the utility of the symmetry reduction, we apply it to a model of the pilot-wave system with a central harmonic force. We begin our analysis by identifying local bifurcations and the onset of chaos. We then describe the emergence of chaotic regions and their merging bifurcations, which lead to the formation of a global attractor. In this final regime, the droplet’s angular momentum spontaneously changes its sign as observed in the experiments of Perrard et al. article_number: '013122' article_processing_charge: No article_type: original author: - first_name: Nazmi B full_name: Budanur, Nazmi B id: 3EA1010E-F248-11E8-B48F-1D18A9856A87 last_name: Budanur orcid: 0000-0003-0423-5010 - first_name: Marc full_name: Fleury, Marc last_name: Fleury citation: ama: 'Budanur NB, Fleury M. State space geometry of the chaotic pilot-wave hydrodynamics. Chaos: An Interdisciplinary Journal of Nonlinear Science. 2019;29(1). doi:10.1063/1.5058279' apa: 'Budanur, N. B., & Fleury, M. (2019). State space geometry of the chaotic pilot-wave hydrodynamics. Chaos: An Interdisciplinary Journal of Nonlinear Science. AIP Publishing. https://doi.org/10.1063/1.5058279' chicago: 'Budanur, Nazmi B, and Marc Fleury. “State Space Geometry of the Chaotic Pilot-Wave Hydrodynamics.” Chaos: An Interdisciplinary Journal of Nonlinear Science. AIP Publishing, 2019. https://doi.org/10.1063/1.5058279.' ieee: 'N. B. Budanur and M. Fleury, “State space geometry of the chaotic pilot-wave hydrodynamics,” Chaos: An Interdisciplinary Journal of Nonlinear Science, vol. 29, no. 1. AIP Publishing, 2019.' ista: 'Budanur NB, Fleury M. 2019. State space geometry of the chaotic pilot-wave hydrodynamics. Chaos: An Interdisciplinary Journal of Nonlinear Science. 29(1), 013122.' mla: 'Budanur, Nazmi B., and Marc Fleury. “State Space Geometry of the Chaotic Pilot-Wave Hydrodynamics.” Chaos: An Interdisciplinary Journal of Nonlinear Science, vol. 29, no. 1, 013122, AIP Publishing, 2019, doi:10.1063/1.5058279.' short: 'N.B. Budanur, M. Fleury, Chaos: An Interdisciplinary Journal of Nonlinear Science 29 (2019).' date_created: 2019-01-23T08:35:09Z date_published: 2019-01-22T00:00:00Z date_updated: 2023-08-25T10:16:11Z day: '22' department: - _id: BjHo doi: 10.1063/1.5058279 external_id: arxiv: - '1812.09011' isi: - '000457409100028' intvolume: ' 29' isi: 1 issue: '1' language: - iso: eng main_file_link: - open_access: '1' url: https://arxiv.org/abs/1812.09011 month: '01' oa: 1 oa_version: Preprint publication: 'Chaos: An Interdisciplinary Journal of Nonlinear Science' publication_identifier: eissn: - 1089-7682 issn: - 1054-1500 publication_status: published publisher: AIP Publishing quality_controlled: '1' related_material: link: - relation: erratum url: https://aip.scitation.org/doi/abs/10.1063/1.5097157 scopus_import: '1' status: public title: State space geometry of the chaotic pilot-wave hydrodynamics type: journal_article user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8 volume: 29 year: '2019' ... --- _id: '6413' abstract: - lang: eng text: Phase-field methods have long been used to model the flow of immiscible fluids. Their ability to naturally capture interface topological changes is widely recognized, but their accuracy in simulating flows of real fluids in practical geometries is not established. We here quantitatively investigate the convergence of the phase-field method to the sharp-interface limit with simulations of two-phase pipe flow. We focus on core-annular flows, in which a highly viscous fluid is lubricated by a less viscous fluid, and validate our simulations with an analytic laminar solution, a formal linear stability analysis and also in the fully nonlinear regime. We demonstrate the ability of the phase-field method to accurately deal with non-rectangular geometry, strong advection, unsteady fluctuations and large viscosity contrast. We argue that phase-field methods are very promising for quantitatively studying moderately turbulent flows, especially at high concentrations of the disperse phase. article_processing_charge: No article_type: original author: - first_name: Baofang full_name: Song, Baofang last_name: Song - first_name: Carlos full_name: Plana, Carlos last_name: Plana - first_name: Jose M full_name: Lopez Alonso, Jose M id: 40770848-F248-11E8-B48F-1D18A9856A87 last_name: Lopez Alonso orcid: 0000-0002-0384-2022 - first_name: Marc full_name: Avila, Marc last_name: Avila citation: ama: Song B, Plana C, Lopez Alonso JM, Avila M. Phase-field simulation of core-annular pipe flow. International Journal of Multiphase Flow. 2019;117:14-24. doi:10.1016/j.ijmultiphaseflow.2019.04.027 apa: Song, B., Plana, C., Lopez Alonso, J. M., & Avila, M. (2019). Phase-field simulation of core-annular pipe flow. International Journal of Multiphase Flow. Elsevier. https://doi.org/10.1016/j.ijmultiphaseflow.2019.04.027 chicago: Song, Baofang, Carlos Plana, Jose M Lopez Alonso, and Marc Avila. “Phase-Field Simulation of Core-Annular Pipe Flow.” International Journal of Multiphase Flow. Elsevier, 2019. https://doi.org/10.1016/j.ijmultiphaseflow.2019.04.027. ieee: B. Song, C. Plana, J. M. Lopez Alonso, and M. Avila, “Phase-field simulation of core-annular pipe flow,” International Journal of Multiphase Flow, vol. 117. Elsevier, pp. 14–24, 2019. ista: Song B, Plana C, Lopez Alonso JM, Avila M. 2019. Phase-field simulation of core-annular pipe flow. International Journal of Multiphase Flow. 117, 14–24. mla: Song, Baofang, et al. “Phase-Field Simulation of Core-Annular Pipe Flow.” International Journal of Multiphase Flow, vol. 117, Elsevier, 2019, pp. 14–24, doi:10.1016/j.ijmultiphaseflow.2019.04.027. short: B. Song, C. Plana, J.M. Lopez Alonso, M. Avila, International Journal of Multiphase Flow 117 (2019) 14–24. date_created: 2019-05-13T07:58:35Z date_published: 2019-08-01T00:00:00Z date_updated: 2023-08-25T10:19:55Z day: '01' department: - _id: BjHo doi: 10.1016/j.ijmultiphaseflow.2019.04.027 external_id: arxiv: - '1902.07351' isi: - '000474496000002' intvolume: ' 117' isi: 1 language: - iso: eng main_file_link: - open_access: '1' url: https://arxiv.org/abs/1902.07351 month: '08' oa: 1 oa_version: Preprint page: 14-24 publication: International Journal of Multiphase Flow publication_identifier: issn: - '03019322' publication_status: published publisher: Elsevier quality_controlled: '1' scopus_import: '1' status: public title: Phase-field simulation of core-annular pipe flow type: journal_article user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8 volume: 117 year: '2019' ... --- _id: '6978' abstract: - lang: eng text: In pipes and channels, the onset of turbulence is initially dominated by localizedtransients, which lead to sustained turbulence through their collective dynamics. In thepresent work, we study numerically the localized turbulence in pipe flow and elucidate astate space structure that gives rise to transient chaos. Starting from the basin boundaryseparating laminar and turbulent flow, we identify transverse homoclinic orbits, thepresence of which necessitates a homoclinic tangle and chaos. A direct consequence ofthe homoclinic tangle is the fractal nature of the laminar-turbulent boundary, which wasconjectured in various earlier studies. By mapping the transverse intersections between thestable and unstable manifold of a periodic orbit, we identify the gateways that promote anescape from turbulence. acknowledged_ssus: - _id: ScienComp article_processing_charge: No article_type: original author: - first_name: Nazmi B full_name: Budanur, Nazmi B id: 3EA1010E-F248-11E8-B48F-1D18A9856A87 last_name: Budanur orcid: 0000-0003-0423-5010 - first_name: Akshunna full_name: Dogra, Akshunna last_name: Dogra - first_name: Björn full_name: Hof, Björn id: 3A374330-F248-11E8-B48F-1D18A9856A87 last_name: Hof orcid: 0000-0003-2057-2754 citation: ama: Budanur NB, Dogra A, Hof B. Geometry of transient chaos in streamwise-localized pipe flow turbulence. Physical Review Fluids. 2019;4(10):102401. doi:10.1103/PhysRevFluids.4.102401 apa: Budanur, N. B., Dogra, A., & Hof, B. (2019). Geometry of transient chaos in streamwise-localized pipe flow turbulence. Physical Review Fluids. American Physical Society. https://doi.org/10.1103/PhysRevFluids.4.102401 chicago: Budanur, Nazmi B, Akshunna Dogra, and Björn Hof. “Geometry of Transient Chaos in Streamwise-Localized Pipe Flow Turbulence.” Physical Review Fluids. American Physical Society, 2019. https://doi.org/10.1103/PhysRevFluids.4.102401. ieee: N. B. Budanur, A. Dogra, and B. Hof, “Geometry of transient chaos in streamwise-localized pipe flow turbulence,” Physical Review Fluids, vol. 4, no. 10. American Physical Society, p. 102401, 2019. ista: Budanur NB, Dogra A, Hof B. 2019. Geometry of transient chaos in streamwise-localized pipe flow turbulence. Physical Review Fluids. 4(10), 102401. mla: Budanur, Nazmi B., et al. “Geometry of Transient Chaos in Streamwise-Localized Pipe Flow Turbulence.” Physical Review Fluids, vol. 4, no. 10, American Physical Society, 2019, p. 102401, doi:10.1103/PhysRevFluids.4.102401. short: N.B. Budanur, A. Dogra, B. Hof, Physical Review Fluids 4 (2019) 102401. date_created: 2019-11-04T10:04:01Z date_published: 2019-10-01T00:00:00Z date_updated: 2023-08-30T07:20:03Z day: '01' department: - _id: BjHo doi: 10.1103/PhysRevFluids.4.102401 external_id: arxiv: - '1810.02211' isi: - '000493510400001' intvolume: ' 4' isi: 1 issue: '10' language: - iso: eng main_file_link: - open_access: '1' url: https://arxiv.org/abs/1810.02211 month: '10' oa: 1 oa_version: Preprint page: '102401' publication: Physical Review Fluids publication_status: published publisher: American Physical Society quality_controlled: '1' scopus_import: '1' status: public title: Geometry of transient chaos in streamwise-localized pipe flow turbulence type: journal_article user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8 volume: 4 year: '2019' ... --- _id: '7397' abstract: - lang: eng text: Polymer additives can substantially reduce the drag of turbulent flows and the upperlimit, the so called “maximum drag reduction” (MDR) asymptote is universal, i.e. inde-pendent of the type of polymer and solvent used. Until recently, the consensus was that,in this limit, flows are in a marginal state where only a minimal level of turbulence activ-ity persists. Observations in direct numerical simulations using minimal sized channelsappeared to support this view and reported long “hibernation” periods where turbu-lence is marginalized. In simulations of pipe flow we find that, indeed, with increasingWeissenberg number (Wi), turbulence expresses long periods of hibernation if the domainsize is small. However, with increasing pipe length, the temporal hibernation continuouslyalters to spatio-temporal intermittency and here the flow consists of turbulent puffs sur-rounded by laminar flow. Moreover, upon an increase in Wi, the flow fully relaminarises,in agreement with recent experiments. At even larger Wi, a different instability is en-countered causing a drag increase towards MDR. Our findings hence link earlier minimalflow unit simulations with recent experiments and confirm that the addition of polymersinitially suppresses Newtonian turbulence and leads to a reverse transition. The MDRstate on the other hand results from a separate instability and the underlying dynamicscorresponds to the recently proposed state of elasto-inertial-turbulence (EIT). article_processing_charge: No article_type: original author: - first_name: Jose M full_name: Lopez Alonso, Jose M id: 40770848-F248-11E8-B48F-1D18A9856A87 last_name: Lopez Alonso orcid: 0000-0002-0384-2022 - first_name: George H full_name: Choueiri, George H id: 448BD5BC-F248-11E8-B48F-1D18A9856A87 last_name: Choueiri - first_name: Björn full_name: Hof, Björn id: 3A374330-F248-11E8-B48F-1D18A9856A87 last_name: Hof orcid: 0000-0003-2057-2754 citation: ama: Lopez Alonso JM, Choueiri GH, Hof B. Dynamics of viscoelastic pipe flow at low Reynolds numbers in the maximum drag reduction limit. Journal of Fluid Mechanics. 2019;874:699-719. doi:10.1017/jfm.2019.486 apa: Lopez Alonso, J. M., Choueiri, G. H., & Hof, B. (2019). Dynamics of viscoelastic pipe flow at low Reynolds numbers in the maximum drag reduction limit. Journal of Fluid Mechanics. CUP. https://doi.org/10.1017/jfm.2019.486 chicago: Lopez Alonso, Jose M, George H Choueiri, and Björn Hof. “Dynamics of Viscoelastic Pipe Flow at Low Reynolds Numbers in the Maximum Drag Reduction Limit.” Journal of Fluid Mechanics. CUP, 2019. https://doi.org/10.1017/jfm.2019.486. ieee: J. M. Lopez Alonso, G. H. Choueiri, and B. Hof, “Dynamics of viscoelastic pipe flow at low Reynolds numbers in the maximum drag reduction limit,” Journal of Fluid Mechanics, vol. 874. CUP, pp. 699–719, 2019. ista: Lopez Alonso JM, Choueiri GH, Hof B. 2019. Dynamics of viscoelastic pipe flow at low Reynolds numbers in the maximum drag reduction limit. Journal of Fluid Mechanics. 874, 699–719. mla: Lopez Alonso, Jose M., et al. “Dynamics of Viscoelastic Pipe Flow at Low Reynolds Numbers in the Maximum Drag Reduction Limit.” Journal of Fluid Mechanics, vol. 874, CUP, 2019, pp. 699–719, doi:10.1017/jfm.2019.486. short: J.M. Lopez Alonso, G.H. Choueiri, B. Hof, Journal of Fluid Mechanics 874 (2019) 699–719. date_created: 2020-01-29T16:05:19Z date_published: 2019-09-10T00:00:00Z date_updated: 2023-09-06T15:36:36Z day: '10' department: - _id: BjHo doi: 10.1017/jfm.2019.486 external_id: arxiv: - '1808.04080' isi: - '000475349900001' intvolume: ' 874' isi: 1 language: - iso: eng main_file_link: - open_access: '1' url: https://arxiv.org/abs/1808.04080 month: '09' oa: 1 oa_version: Preprint page: 699-719 publication: Journal of Fluid Mechanics publication_identifier: eissn: - 1469-7645 issn: - 0022-1120 publication_status: published publisher: CUP quality_controlled: '1' scopus_import: '1' status: public title: Dynamics of viscoelastic pipe flow at low Reynolds numbers in the maximum drag reduction limit type: journal_article user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 volume: 874 year: '2019' ... --- _id: '6957' abstract: - lang: eng text: "In many shear flows like pipe flow, plane Couette flow, plane Poiseuille flow, etc. turbulence emerges subcritically. Here, when subjected to strong enough perturbations, the flow becomes turbulent in spite of the laminar base flow being linearly stable. The nature of this instability has puzzled the scientific community for decades. At onset, turbulence appears in localized patches and flows are spatio-temporally intermittent. In pipe flow the localized turbulent structures are referred to as puffs and in planar flows like plane Couette and channel flow, patches arise in the form of localized oblique bands. In this thesis, we study the onset of turbulence in channel flow in direct numerical simulations from a dynamical system theory perspective, as well as by performing experiments in a large aspect ratio channel.\r\n\r\nThe aim of the experimental work is to determine the critical Reynolds number where turbulence first becomes sustained. Recently, the onset of turbulence has been described in analogy to absorbing state phase transition (i.e. directed percolation). In particular, it has been shown that the critical point can be estimated from the competition between spreading and decay processes. Here, by performing experiments, we identify the mechanisms underlying turbulence proliferation in channel flow and find the critical Reynolds number, above which turbulence becomes sustained. Above the critical point, the continuous growth at the tip of the stripes outweighs the stochastic shedding of turbulent patches at the tail and the stripes expand. For growing stripes, the probability to decay decreases while the probability of stripe splitting increases. Consequently, and unlike for the puffs in pipe flow, neither of these two processes is time-independent i.e. memoryless. Coupling between stripe expansion and creation of new stripes via splitting leads to a significantly lower critical point ($Re_c=670+/-10$) than most earlier studies suggest. \r\n\r\nWhile the above approach sheds light on how turbulence first becomes sustained, it provides no insight into the origin of the stripes themselves. In the numerical part of the thesis we investigate how turbulent stripes form from invariant solutions of the Navier-Stokes equations. The origin of these turbulent stripes can be identified by applying concepts from the dynamical system theory. In doing so, we identify the exact coherent structures underlying stripes and their bifurcations and how they give rise to the turbulent attractor in phase space. We first report a family of localized nonlinear traveling wave solutions of the Navier-Stokes equations in channel flow. These solutions show structural similarities with turbulent stripes in experiments like obliqueness, quasi-streamwise streaks and vortices, etc. A parametric study of these traveling wave solution is performed, with parameters like Reynolds number, stripe tilt angle and domain size, including the stability of the solutions. These solutions emerge through saddle-node bifurcations and form a phase space skeleton for the turbulent stripes observed in the experiments. The lower branches of these TW solutions at different tilt angles undergo Hopf bifurcation and new solutions branches of relative periodic orbits emerge. These RPO solutions do not belong to the same family and therefore the routes to chaos for different angles are different. \r\n\r\nIn shear flows, turbulence at onset is transient in nature. \ Consequently,turbulence can not be tracked to lower Reynolds numbers, where the dynamics may simplify. Before this happens, turbulence becomes short-lived and laminarizes. In the last part of the thesis, we show that using numerical simulations we can continue turbulent stripes in channel flow past the 'relaminarization barrier' all the way to their origin. Here, turbulent stripe dynamics simplifies and the fluctuations are no longer stochastic and the stripe settles down to a relative periodic orbit. This relative periodic orbit originates from the aforementioned traveling wave solutions. Starting from the relative periodic orbit, a small increase in speed i.e. Reynolds number gives rise to chaos and the attractor dimension sharply increases in contrast to the classical transition scenario where the instabilities affect the flow globally and give rise to much more gradual route to turbulence." alternative_title: - ISTA Thesis article_processing_charge: No author: - first_name: Chaitanya S full_name: Paranjape, Chaitanya S id: 3D85B7C4-F248-11E8-B48F-1D18A9856A87 last_name: Paranjape citation: ama: Paranjape CS. Onset of turbulence in plane Poiseuille flow. 2019. doi:10.15479/AT:ISTA:6957 apa: Paranjape, C. S. (2019). Onset of turbulence in plane Poiseuille flow. Institute of Science and Technology Austria. https://doi.org/10.15479/AT:ISTA:6957 chicago: Paranjape, Chaitanya S. “Onset of Turbulence in Plane Poiseuille Flow.” Institute of Science and Technology Austria, 2019. https://doi.org/10.15479/AT:ISTA:6957. ieee: C. S. Paranjape, “Onset of turbulence in plane Poiseuille flow,” Institute of Science and Technology Austria, 2019. ista: Paranjape CS. 2019. Onset of turbulence in plane Poiseuille flow. Institute of Science and Technology Austria. mla: Paranjape, Chaitanya S. Onset of Turbulence in Plane Poiseuille Flow. Institute of Science and Technology Austria, 2019, doi:10.15479/AT:ISTA:6957. short: C.S. Paranjape, Onset of Turbulence in Plane Poiseuille Flow, Institute of Science and Technology Austria, 2019. date_created: 2019-10-22T12:08:43Z date_published: 2019-10-24T00:00:00Z date_updated: 2023-09-07T12:53:25Z day: '24' ddc: - '532' degree_awarded: PhD department: - _id: BjHo doi: 10.15479/AT:ISTA:6957 file: - access_level: closed checksum: 7ba298ba0ce7e1d11691af6b8eaf0a0a content_type: application/zip creator: cparanjape date_created: 2019-10-23T09:54:43Z date_updated: 2020-07-14T12:47:46Z file_id: '6962' file_name: Chaitanya_Paranjape_source_files_tex_figures.zip file_size: 45828099 relation: source_file - access_level: open_access checksum: 642697618314e31ac31392da7909c2d9 content_type: application/pdf creator: cparanjape date_created: 2019-10-23T10:37:09Z date_updated: 2020-07-14T12:47:46Z file_id: '6963' file_name: Chaitanya_Paranjape_Thesis.pdf file_size: 19504197 relation: main_file file_date_updated: 2020-07-14T12:47:46Z has_accepted_license: '1' keyword: - Instabilities - Turbulence - Nonlinear dynamics language: - iso: eng month: '10' oa: 1 oa_version: Published Version page: '138' publication_identifier: eissn: - 2663-337X publication_status: published publisher: Institute of Science and Technology Austria status: public supervisor: - first_name: Björn full_name: Hof, Björn id: 3A374330-F248-11E8-B48F-1D18A9856A87 last_name: Hof orcid: 0000-0003-2057-2754 title: Onset of turbulence in plane Poiseuille flow type: dissertation user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 year: '2019' ... --- _id: '7197' abstract: - lang: eng text: During bacterial cell division, the tubulin-homolog FtsZ forms a ring-like structure at the center of the cell. This Z-ring not only organizes the division machinery, but treadmilling of FtsZ filaments was also found to play a key role in distributing proteins at the division site. What regulates the architecture, dynamics and stability of the Z-ring is currently unknown, but FtsZ-associated proteins are known to play an important role. Here, using an in vitro reconstitution approach, we studied how the well-conserved protein ZapA affects FtsZ treadmilling and filament organization into large-scale patterns. Using high-resolution fluorescence microscopy and quantitative image analysis, we found that ZapA cooperatively increases the spatial order of the filament network, but binds only transiently to FtsZ filaments and has no effect on filament length and treadmilling velocity. Together, our data provides a model for how FtsZ-associated proteins can increase the precision and stability of the bacterial cell division machinery in a switch-like manner. acknowledged_ssus: - _id: LifeSc - _id: Bio article_number: '5744' article_processing_charge: No article_type: original author: - first_name: Paulo R full_name: Dos Santos Caldas, Paulo R id: 38FCDB4C-F248-11E8-B48F-1D18A9856A87 last_name: Dos Santos Caldas orcid: 0000-0001-6730-4461 - first_name: Maria D full_name: Lopez Pelegrin, Maria D id: 319AA9CE-F248-11E8-B48F-1D18A9856A87 last_name: Lopez Pelegrin - first_name: Daniel J. G. full_name: Pearce, Daniel J. G. last_name: Pearce - first_name: Nazmi B full_name: Budanur, Nazmi B id: 3EA1010E-F248-11E8-B48F-1D18A9856A87 last_name: Budanur orcid: 0000-0003-0423-5010 - first_name: Jan full_name: Brugués, Jan last_name: Brugués - first_name: Martin full_name: Loose, Martin id: 462D4284-F248-11E8-B48F-1D18A9856A87 last_name: Loose orcid: 0000-0001-7309-9724 citation: ama: Dos Santos Caldas PR, Lopez Pelegrin MD, Pearce DJG, Budanur NB, Brugués J, Loose M. Cooperative ordering of treadmilling filaments in cytoskeletal networks of FtsZ and its crosslinker ZapA. Nature Communications. 2019;10. doi:10.1038/s41467-019-13702-4 apa: Dos Santos Caldas, P. R., Lopez Pelegrin, M. D., Pearce, D. J. G., Budanur, N. B., Brugués, J., & Loose, M. (2019). Cooperative ordering of treadmilling filaments in cytoskeletal networks of FtsZ and its crosslinker ZapA. Nature Communications. Springer Nature. https://doi.org/10.1038/s41467-019-13702-4 chicago: Dos Santos Caldas, Paulo R, Maria D Lopez Pelegrin, Daniel J. G. Pearce, Nazmi B Budanur, Jan Brugués, and Martin Loose. “Cooperative Ordering of Treadmilling Filaments in Cytoskeletal Networks of FtsZ and Its Crosslinker ZapA.” Nature Communications. Springer Nature, 2019. https://doi.org/10.1038/s41467-019-13702-4. ieee: P. R. Dos Santos Caldas, M. D. Lopez Pelegrin, D. J. G. Pearce, N. B. Budanur, J. Brugués, and M. Loose, “Cooperative ordering of treadmilling filaments in cytoskeletal networks of FtsZ and its crosslinker ZapA,” Nature Communications, vol. 10. Springer Nature, 2019. ista: Dos Santos Caldas PR, Lopez Pelegrin MD, Pearce DJG, Budanur NB, Brugués J, Loose M. 2019. Cooperative ordering of treadmilling filaments in cytoskeletal networks of FtsZ and its crosslinker ZapA. Nature Communications. 10, 5744. mla: Dos Santos Caldas, Paulo R., et al. “Cooperative Ordering of Treadmilling Filaments in Cytoskeletal Networks of FtsZ and Its Crosslinker ZapA.” Nature Communications, vol. 10, 5744, Springer Nature, 2019, doi:10.1038/s41467-019-13702-4. short: P.R. Dos Santos Caldas, M.D. Lopez Pelegrin, D.J.G. Pearce, N.B. Budanur, J. Brugués, M. Loose, Nature Communications 10 (2019). date_created: 2019-12-20T12:22:57Z date_published: 2019-12-17T00:00:00Z date_updated: 2023-09-07T13:18:51Z day: '17' ddc: - '570' department: - _id: MaLo - _id: BjHo doi: 10.1038/s41467-019-13702-4 ec_funded: 1 external_id: isi: - '000503009300001' file: - access_level: open_access checksum: a1b44b427ba341383197790d0e8789fa content_type: application/pdf creator: dernst date_created: 2019-12-23T07:34:56Z date_updated: 2020-07-14T12:47:53Z file_id: '7208' file_name: 2019_NatureComm_Caldas.pdf file_size: 8488733 relation: main_file file_date_updated: 2020-07-14T12:47:53Z has_accepted_license: '1' intvolume: ' 10' isi: 1 language: - iso: eng license: https://creativecommons.org/licenses/by/4.0/ month: '12' oa: 1 oa_version: Published Version project: - _id: 2595697A-B435-11E9-9278-68D0E5697425 call_identifier: H2020 grant_number: '679239' name: Self-Organization of the Bacterial Cell - _id: 260D98C8-B435-11E9-9278-68D0E5697425 name: Reconstitution of Bacterial Cell Division Using Purified Components publication: Nature Communications publication_identifier: issn: - 2041-1723 publication_status: published publisher: Springer Nature quality_controlled: '1' related_material: record: - id: '8358' relation: dissertation_contains status: public scopus_import: '1' status: public title: Cooperative ordering of treadmilling filaments in cytoskeletal networks of FtsZ and its crosslinker ZapA tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 volume: 10 year: '2019' ... --- _id: '6069' abstract: - lang: eng text: Electron transport in two-dimensional conducting materials such as graphene, with dominant electron–electron interaction, exhibits unusual vortex flow that leads to a nonlocal current-field relation (negative resistance), distinct from the classical Ohm’s law. The transport behavior of these materials is best described by low Reynolds number hydrodynamics, where the constitutive pressure–speed relation is Stoke’s law. Here we report evidence of such vortices observed in a viscous flow of Newtonian fluid in a microfluidic device consisting of a rectangular cavity—analogous to the electronic system. We extend our experimental observations to elliptic cavities of different eccentricities, and validate them by numerically solving bi-harmonic equation obtained for the viscous flow with no-slip boundary conditions. We verify the existence of a predicted threshold at which vortices appear. Strikingly, we find that a two-dimensional theoretical model captures the essential features of three-dimensional Stokes flow in experiments. article_number: '937' article_processing_charge: No author: - first_name: Jonathan full_name: Mayzel, Jonathan last_name: Mayzel - first_name: Victor full_name: Steinberg, Victor last_name: Steinberg - first_name: Atul full_name: Varshney, Atul id: 2A2006B2-F248-11E8-B48F-1D18A9856A87 last_name: Varshney orcid: 0000-0002-3072-5999 citation: ama: Mayzel J, Steinberg V, Varshney A. Stokes flow analogous to viscous electron current in graphene. Nature Communications. 2019;10. doi:10.1038/s41467-019-08916-5 apa: Mayzel, J., Steinberg, V., & Varshney, A. (2019). Stokes flow analogous to viscous electron current in graphene. Nature Communications. Springer Nature. https://doi.org/10.1038/s41467-019-08916-5 chicago: Mayzel, Jonathan, Victor Steinberg, and Atul Varshney. “Stokes Flow Analogous to Viscous Electron Current in Graphene.” Nature Communications. Springer Nature, 2019. https://doi.org/10.1038/s41467-019-08916-5. ieee: J. Mayzel, V. Steinberg, and A. Varshney, “Stokes flow analogous to viscous electron current in graphene,” Nature Communications, vol. 10. Springer Nature, 2019. ista: Mayzel J, Steinberg V, Varshney A. 2019. Stokes flow analogous to viscous electron current in graphene. Nature Communications. 10, 937. mla: Mayzel, Jonathan, et al. “Stokes Flow Analogous to Viscous Electron Current in Graphene.” Nature Communications, vol. 10, 937, Springer Nature, 2019, doi:10.1038/s41467-019-08916-5. short: J. Mayzel, V. Steinberg, A. Varshney, Nature Communications 10 (2019). date_created: 2019-03-05T13:18:30Z date_published: 2019-02-26T00:00:00Z date_updated: 2023-09-08T11:39:02Z day: '26' ddc: - '530' - '532' department: - _id: BjHo doi: 10.1038/s41467-019-08916-5 ec_funded: 1 external_id: isi: - '000459704600001' file: - access_level: open_access checksum: 61192fc49e0d44907c2a4fe384e4b97f content_type: application/pdf creator: dernst date_created: 2019-03-05T13:33:04Z date_updated: 2020-07-14T12:47:18Z file_id: '6070' file_name: 2019_NatureComm_Mayzel.pdf file_size: 2646391 relation: main_file file_date_updated: 2020-07-14T12:47:18Z has_accepted_license: '1' intvolume: ' 10' isi: 1 language: - iso: eng month: '02' oa: 1 oa_version: Published Version project: - _id: 260C2330-B435-11E9-9278-68D0E5697425 call_identifier: H2020 grant_number: '754411' name: ISTplus - Postdoctoral Fellowships publication: Nature Communications publication_identifier: issn: - 2041-1723 publication_status: published publisher: Springer Nature quality_controlled: '1' scopus_import: '1' status: public title: Stokes flow analogous to viscous electron current in graphene tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 volume: 10 year: '2019' ... --- _id: '6014' abstract: - lang: eng text: Speed of sound waves in gases and liquids are governed by the compressibility of the medium. There exists another type of non-dispersive wave where the wave speed depends on stress instead of elasticity of the medium. A well-known example is the Alfven wave, which propagates through plasma permeated by a magnetic field with the speed determined by magnetic tension. An elastic analogue of Alfven waves has been predicted in a flow of dilute polymer solution where the elastic stress of the stretching polymers determines the elastic wave speed. Here we present quantitative evidence of elastic Alfven waves in elastic turbulence of a viscoelastic creeping flow between two obstacles in channel flow. The key finding in the experimental proof is a nonlinear dependence of the elastic wave speed cel on the Weissenberg number Wi, which deviates from predictions based on a model of linear polymer elasticity. article_number: '652' article_processing_charge: No article_type: original author: - first_name: Atul full_name: Varshney, Atul id: 2A2006B2-F248-11E8-B48F-1D18A9856A87 last_name: Varshney orcid: 0000-0002-3072-5999 - first_name: Victor full_name: Steinberg, Victor last_name: Steinberg citation: ama: Varshney A, Steinberg V. Elastic alfven waves in elastic turbulence. Nature Communications. 2019;10. doi:10.1038/s41467-019-08551-0 apa: Varshney, A., & Steinberg, V. (2019). Elastic alfven waves in elastic turbulence. Nature Communications. Springer Nature. https://doi.org/10.1038/s41467-019-08551-0 chicago: Varshney, Atul, and Victor Steinberg. “Elastic Alfven Waves in Elastic Turbulence.” Nature Communications. Springer Nature, 2019. https://doi.org/10.1038/s41467-019-08551-0. ieee: A. Varshney and V. Steinberg, “Elastic alfven waves in elastic turbulence,” Nature Communications, vol. 10. Springer Nature, 2019. ista: Varshney A, Steinberg V. 2019. Elastic alfven waves in elastic turbulence. Nature Communications. 10, 652. mla: Varshney, Atul, and Victor Steinberg. “Elastic Alfven Waves in Elastic Turbulence.” Nature Communications, vol. 10, 652, Springer Nature, 2019, doi:10.1038/s41467-019-08551-0. short: A. Varshney, V. Steinberg, Nature Communications 10 (2019). date_created: 2019-02-15T07:10:46Z date_published: 2019-02-08T00:00:00Z date_updated: 2023-09-08T11:39:54Z day: '08' ddc: - '530' department: - _id: BjHo doi: 10.1038/s41467-019-08551-0 ec_funded: 1 external_id: arxiv: - '1902.03763' isi: - '000458175300001' file: - access_level: open_access checksum: d3acf07eaad95ec040d8e8565fc9ac37 content_type: application/pdf creator: dernst date_created: 2019-02-15T07:15:00Z date_updated: 2020-07-14T12:47:17Z file_id: '6015' file_name: 2019_NatureComm_Varshney.pdf file_size: 1331490 relation: main_file file_date_updated: 2020-07-14T12:47:17Z has_accepted_license: '1' intvolume: ' 10' isi: 1 language: - iso: eng month: '02' oa: 1 oa_version: Published Version project: - _id: 260C2330-B435-11E9-9278-68D0E5697425 call_identifier: H2020 grant_number: '754411' name: ISTplus - Postdoctoral Fellowships publication: Nature Communications publication_identifier: issn: - 2041-1723 publication_status: published publisher: Springer Nature quality_controlled: '1' scopus_import: '1' status: public title: Elastic alfven waves in elastic turbulence tmp: image: /images/cc_by.png legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0) short: CC BY (4.0) type: journal_article user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1 volume: 10 year: '2019' ... --- _id: '6779' abstract: - lang: eng text: "Recent studies suggest that unstable recurrent solutions of the Navier-Stokes equation provide new insights\r\ninto dynamics of turbulent flows. In this study, we compute an extensive network of dynamical connections\r\nbetween such solutions in a weakly turbulent quasi-two-dimensional Kolmogorov flow that lies in the inversion symmetric subspace. In particular, we find numerous isolated heteroclinic connections between different\r\ntypes of solutions—equilibria, periodic, and quasiperiodic orbits—as well as continua of connections forming\r\nhigher-dimensional connecting manifolds. We also compute a homoclinic connection of a periodic orbit and\r\nprovide strong evidence that the associated homoclinic tangle forms the chaotic repeller that underpins transient\r\nturbulence in the symmetric subspace." article_number: '013112' article_processing_charge: No article_type: original author: - first_name: Balachandra full_name: Suri, Balachandra id: 47A5E706-F248-11E8-B48F-1D18A9856A87 last_name: Suri - first_name: Ravi Kumar full_name: Pallantla, Ravi Kumar last_name: Pallantla - first_name: Michael F. full_name: Schatz, Michael F. last_name: Schatz - first_name: Roman O. full_name: Grigoriev, Roman O. last_name: Grigoriev citation: ama: Suri B, Pallantla RK, Schatz MF, Grigoriev RO. Heteroclinic and homoclinic connections in a Kolmogorov-like flow. Physical Review E. 2019;100(1). doi:10.1103/physreve.100.013112 apa: Suri, B., Pallantla, R. K., Schatz, M. F., & Grigoriev, R. O. (2019). Heteroclinic and homoclinic connections in a Kolmogorov-like flow. Physical Review E. American Physical Society. https://doi.org/10.1103/physreve.100.013112 chicago: Suri, Balachandra, Ravi Kumar Pallantla, Michael F. Schatz, and Roman O. Grigoriev. “Heteroclinic and Homoclinic Connections in a Kolmogorov-like Flow.” Physical Review E. American Physical Society, 2019. https://doi.org/10.1103/physreve.100.013112. ieee: B. Suri, R. K. Pallantla, M. F. Schatz, and R. O. Grigoriev, “Heteroclinic and homoclinic connections in a Kolmogorov-like flow,” Physical Review E, vol. 100, no. 1. American Physical Society, 2019. ista: Suri B, Pallantla RK, Schatz MF, Grigoriev RO. 2019. Heteroclinic and homoclinic connections in a Kolmogorov-like flow. Physical Review E. 100(1), 013112. mla: Suri, Balachandra, et al. “Heteroclinic and Homoclinic Connections in a Kolmogorov-like Flow.” Physical Review E, vol. 100, no. 1, 013112, American Physical Society, 2019, doi:10.1103/physreve.100.013112. short: B. Suri, R.K. Pallantla, M.F. Schatz, R.O. Grigoriev, Physical Review E 100 (2019). date_created: 2019-08-09T09:40:41Z date_published: 2019-07-25T00:00:00Z date_updated: 2024-02-28T13:13:00Z day: '25' ddc: - '532' department: - _id: BjHo doi: 10.1103/physreve.100.013112 ec_funded: 1 external_id: arxiv: - '1907.05860' isi: - '000477911800012' intvolume: ' 100' isi: 1 issue: '1' language: - iso: eng main_file_link: - open_access: '1' url: https://arxiv.org/abs/1907.05860 month: '07' oa: 1 oa_version: Preprint project: - _id: 25681D80-B435-11E9-9278-68D0E5697425 call_identifier: FP7 grant_number: '291734' name: International IST Postdoc Fellowship Programme publication: Physical Review E publication_identifier: eissn: - 2470-0053 issn: - 2470-0045 publication_status: published publisher: American Physical Society quality_controlled: '1' scopus_import: '1' status: public title: Heteroclinic and homoclinic connections in a Kolmogorov-like flow type: journal_article user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87 volume: 100 year: '2019' ...