de.pangaea.dataset929197 und dataset PANGAEA
info@pangaea.de
https://www.pangaea.de/ information pointOfContact 2026-07-15T19:15:29Z https://doi.pangaea.de/10.1594/PANGAEA.929197 <gco:CharacterString>Optimal perturbation (classic, Re=2000,A=1,Wo=15): Time series of the r-theta-z-components contributions to the kinetic energy and enstrophy</gco:CharacterString> 2021-03-16T07:50:42 publication https://doi.org/10.1594/PANGAEA.929197 Xu, Duo
duo.xu@zarm.uni-bremen.de
https://orcid.org/0000-0001-8330-3581 information author Song, Baofang https://orcid.org/0000-0003-4469-8781 information author Avila, Marc
marc.avila@zarm.uni-bremen.de
https://orcid.org/0000-0001-5988-1090 information author PANGAEA
info@pangaea.de
https://www.pangaea.de/ information publisher tableDigital Laminar flows through pipes driven at steady, pulsatile or oscillatory rates undergo a subcritical transition to turbulence. We carry out an extensive linear non-modal stability analysis of these flows and show that for sufficiently high pulsation amplitudes the stream-wise vortices of the classic lift-up mechanism are outperformed by helical disturbances exhibiting an Orr-like mechanism. In oscillatory flow, the energy amplification depends solely on the Reynolds number based on the Stokes-layer thickness, and for sufficiently high oscillation frequency and Reynolds number, axisymmetric disturbances dominate. In the high-frequency limit, these axisymmetric disturbances are exactly similar to those recently identified by Biau (J. Fluid Mech., vol. 794, 2016, R4) for oscillatory flow over a flat plate. In all regimes of pulsatile and oscillatory pipe flow, the optimal helical and axisymmetric disturbances are triggered in the deceleration phase and reach their peaks in typically less than a period. Their maximum energy gain scales exponentially with Reynolds number of the oscillatory flow component. Our numerical computations unveil a plausible mechanism for the turbulence observed experimentally in pulsatile and oscillatory pipe flow. completed Xu, Duo
duo.xu@zarm.uni-bremen.de
https://orcid.org/0000-0001-8330-3581 information principalInvestigator nonlinear instability transition to turbulence theme <gco:CharacterString>PANGAEA Keyword List</gco:CharacterString> 1995-01-01 creation PANGAEA
info@pangaea.de
https://www.pangaea.de/ information pointOfContact copyright copyright CC-BY-4.0: Creative Commons Attribution 4.0 International textTable und geoscientificInformation OptimalPerturbation_classic_time_vel_vort #(k_op,m_op)=(0.00000000,1) VARIABLES = "t", "t/T", "ur", "ut", "uz", "curlr", "curlt", "curlz" ZONE T="time series", I=16755, J=1 Dimensionless time thematicClassification Time by pulsation period thematicClassification Velocity, radial thematicClassification u_θ, velocity, cylindrical, azimuthal component thematicClassification u_z, velocity, cylindrical, axial component thematicClassification Curl of velocity, radial direction thematicClassification Curl of velocity, azimuthal direction thematicClassification Curl of velocity, axial direction thematicClassification text/tab-separated-values unknown https://doi.pangaea.de/10.1594/PANGAEA.929197?format=textfile download dataset The data set was checked for completeness, correctness, and consistency of metainformation. Validity of used methods was checked and - if applicable - precision and range of data. EVENT LABEL: FLUID_SIMULATION_MODELING (FSM) * METHOD/DEVICE: Model simulation Related to <gco:CharacterString>Non-modal transient growth of disturbances in pulsatile and oscillatory pipe flows</gco:CharacterString> https://doi.org/10.1017/jfm.2020.940 Xu, Duo
duo.xu@zarm.uni-bremen.de
https://orcid.org/0000-0001-8330-3581 information author Song, Baofang https://orcid.org/0000-0003-4469-8781 information author Avila, Marc
marc.avila@zarm.uni-bremen.de
https://orcid.org/0000-0001-5988-1090 information author documentDigital Journal of Fluid Mechanics 907