article published Björn Hof author 3A374330-F248-11E8-B48F-1D18A9856A870000-0003-2057-2754 Casimir Van Doorne author Jerry Westerweel author Frans Nieuwstadt author We present the results of an experimental investigation into the nature and structure of turbulent pipe flow at moderate Reynolds numbers. A turbulence regeneration mechanism is identified which sustains a symmetric traveling wave within the flow. The periodicity of the mechanism allows comparison to the wavelength of numerically observed exact traveling wave solutions and close agreement is found. The advection speed of the upstream turbulence laminar interface in the experimental flow is observed to form a lower bound on the phase velocities of the exact traveling wave solutions. Overall our observations suggest that the dynamics of the turbulent flow at moderate Reynolds numbers are governed by unstable nonlinear traveling waves. American Physical Society2005 10.1103/PhysRevLett.95.214502 9521 yes B. Hof, C. Van Doorne, J. Westerweel, F. Nieuwstadt, Physical Review Letters 95 (2005). Hof B, Van Doorne C, Westerweel J, Nieuwstadt F. Turbulence regeneration in pipe flow at moderate reynolds numbers. <i>Physical Review Letters</i>. 2005;95(21). doi:<a href="https://doi.org/10.1103/PhysRevLett.95.214502">10.1103/PhysRevLett.95.214502</a> Hof B, Van Doorne C, Westerweel J, Nieuwstadt F. 2005. Turbulence regeneration in pipe flow at moderate reynolds numbers. Physical Review Letters. 95(21). B. Hof, C. Van Doorne, J. Westerweel, and F. Nieuwstadt, “Turbulence regeneration in pipe flow at moderate reynolds numbers,” <i>Physical Review Letters</i>, vol. 95, no. 21. American Physical Society, 2005. Hof, Björn, Casimir Van Doorne, Jerry Westerweel, and Frans Nieuwstadt. “Turbulence Regeneration in Pipe Flow at Moderate Reynolds Numbers.” <i>Physical Review Letters</i>. American Physical Society, 2005. <a href="https://doi.org/10.1103/PhysRevLett.95.214502">https://doi.org/10.1103/PhysRevLett.95.214502</a>. Hof, Björn, et al. “Turbulence Regeneration in Pipe Flow at Moderate Reynolds Numbers.” <i>Physical Review Letters</i>, vol. 95, no. 21, American Physical Society, 2005, doi:<a href="https://doi.org/10.1103/PhysRevLett.95.214502">10.1103/PhysRevLett.95.214502</a>. Hof, B., Van Doorne, C., Westerweel, J., &#38; Nieuwstadt, F. (2005). Turbulence regeneration in pipe flow at moderate reynolds numbers. <i>Physical Review Letters</i>. American Physical Society. <a href="https://doi.org/10.1103/PhysRevLett.95.214502">https://doi.org/10.1103/PhysRevLett.95.214502</a> 27882018-12-11T11:59:36Z2021-01-12T06:59:43Z