article published yes George H Choueiri author 448BD5BC-F248-11E8-B48F-1D18A9856A87 Jose M Lopez Alonso author 40770848-F248-11E8-B48F-1D18A9856A870000-0002-0384-2022 Atul Varshney author 2A2006B2-F248-11E8-B48F-1D18A9856A870000-0002-3072-5999 Sarath Sankar author Björn Hof author 3A374330-F248-11E8-B48F-1D18A9856A870000-0003-2057-2754 BjHo department Instabilities in pulsating pipe flow in complex fluids project Turbulence generally arises in shear flows if velocities and hence, inertial forces are sufficiently large. In striking contrast, viscoelastic fluids can exhibit disordered motion even at vanishing inertia. Intermediate between these cases, a state of chaotic motion, “elastoinertial turbulence” (EIT), has been observed in a narrow Reynolds number interval. We here determine the origin of EIT in experiments and show that characteristic EIT structures can be detected across an unexpectedly wide range of parameters. Close to onset, a pattern of chevron-shaped streaks emerges in qualitative agreement with linear and weakly nonlinear theory. However, in experiments, the dynamics remain weakly chaotic, and the instability can be traced to far lower Reynolds numbers than permitted by theory. For increasing inertia, the flow undergoes a transformation to a wall mode composed of inclined near-wall streaks and shear layers. This mode persists to what is known as the “maximum drag reduction limit,” and overall EIT is found to dominate viscoelastic flows across more than three orders of magnitude in Reynolds number. National Academy of Sciences2021 eng multidisciplinaryelastoinertial turbulenceviscoelastic flowselastic instabilitydrag reduction 0027-8424 1091-6490 2103.00023 34732570 00072092690001910.1073/pnas.2102350118 11845 https://research-explorer.ista.ac.at/record/19906 Choueiri, G. H., Lopez Alonso, J. M., Varshney, A., Sankar, S., &#38; Hof, B. (2021). Experimental observation of the origin and structure of elastoinertial turbulence. <i>Proceedings of the National Academy of Sciences of the United States of America</i>. National Academy of Sciences. <a href="https://doi.org/10.1073/pnas.2102350118">https://doi.org/10.1073/pnas.2102350118</a> G.H. Choueiri, J.M. Lopez Alonso, A. Varshney, S. Sankar, B. Hof, Proceedings of the National Academy of Sciences of the United States of America 118 (2021). Choueiri GH, Lopez Alonso JM, Varshney A, Sankar S, Hof B. Experimental observation of the origin and structure of elastoinertial turbulence. <i>Proceedings of the National Academy of Sciences of the United States of America</i>. 2021;118(45). doi:<a href="https://doi.org/10.1073/pnas.2102350118">10.1073/pnas.2102350118</a> Choueiri GH, Lopez Alonso JM, Varshney A, Sankar S, Hof B. 2021. Experimental observation of the origin and structure of elastoinertial turbulence. Proceedings of the National Academy of Sciences of the United States of America. 118(45), e2102350118. Choueiri, George H., et al. “Experimental Observation of the Origin and Structure of Elastoinertial Turbulence.” <i>Proceedings of the National Academy of Sciences of the United States of America</i>, vol. 118, no. 45, e2102350118, National Academy of Sciences, 2021, doi:<a href="https://doi.org/10.1073/pnas.2102350118">10.1073/pnas.2102350118</a>. G. H. Choueiri, J. M. Lopez Alonso, A. Varshney, S. Sankar, and B. Hof, “Experimental observation of the origin and structure of elastoinertial turbulence,” <i>Proceedings of the National Academy of Sciences of the United States of America</i>, vol. 118, no. 45. National Academy of Sciences, 2021. Choueiri, George H, Jose M Lopez Alonso, Atul Varshney, Sarath Sankar, and Björn Hof. “Experimental Observation of the Origin and Structure of Elastoinertial Turbulence.” <i>Proceedings of the National Academy of Sciences of the United States of America</i>. National Academy of Sciences, 2021. <a href="https://doi.org/10.1073/pnas.2102350118">https://doi.org/10.1073/pnas.2102350118</a>. 102992021-11-17T13:24:24Z2026-08-08T22:31:04Z