TY - JOUR
T1 - Measuring intense rotation and dissipation in turbulent flows
AU - Zeff, Benjamin W.
AU - Lanterman, Daniel D.
AU - McAllister, Ryan
AU - Roy, Rajarshi
AU - Kostelich, Eric
AU - Lathrop, Daniel P.
N1 - Funding Information:
Acknowledgements We gratefully acknowledge the support of the National Science Foundation and the Research Corporation. R.M. and R.R. gratefully acknowledge support from the Office of Naval Research (Physics Division). We thank D. Levermore, J. Rodgers, D. DeShazer, K. R. Sreenivasan, E. Ott, T. Antonsen and J. Fineberg for advice.
Funding Information:
Acknowledgements We thank B. Buffett for helpful discussions; C. Johnson, R. Jeanloz, M. Manga and H.-P. Bunge for comments; and D. Stevenson and M. Zuber for reviews that improved this manuscript. We dedicate this work to the memory of our co-author Stephen Zatman, who inspired us by his interest in this subject. This work was supported by IGPP LANL, NASA CT project, the National Science Foundation, and the Miller Institute for Basic Research in Science.
PY - 2003/1/9
Y1 - 2003/1/9
N2 - Turbulent flows are highly intermittent - for example, they exhibit intense bursts of vorticity and strain. Kolmogorov theory1,2 describes such behaviour in the form of energy cascades from large to small spatial and temporal scales, where energy is dissipated as heat. But the causes of high intermittency in turbulence, which show non-gaussian statistics3-5, are not well understood. Such intermittency can be important, for example, for enhancing the mixing of chemicals6,7, by producing sharp drops in local pressure that can induce cavitation (damaging mechanical components and biological organisms)8, and by causing intense vortices in atmospheric flows. Here we present observations of the three components of velocity and all nine velocity gradients within a small volume, which allow us to determine simultaneously the dissipation (a measure of strain) and enstrophy (a measure of rotational energy) of a turbulent flow. Combining the statistics of all measurements and the evolution of individual bursts, we find that a typical sequence for intense events begins with rapid strain growth, followed by rising vorticity and a final sudden decline in stretching. We suggest two mechanisms which can produce these characteristics, depending whether they are due to the advection of coherent structures through our observed volume or caused locally.
AB - Turbulent flows are highly intermittent - for example, they exhibit intense bursts of vorticity and strain. Kolmogorov theory1,2 describes such behaviour in the form of energy cascades from large to small spatial and temporal scales, where energy is dissipated as heat. But the causes of high intermittency in turbulence, which show non-gaussian statistics3-5, are not well understood. Such intermittency can be important, for example, for enhancing the mixing of chemicals6,7, by producing sharp drops in local pressure that can induce cavitation (damaging mechanical components and biological organisms)8, and by causing intense vortices in atmospheric flows. Here we present observations of the three components of velocity and all nine velocity gradients within a small volume, which allow us to determine simultaneously the dissipation (a measure of strain) and enstrophy (a measure of rotational energy) of a turbulent flow. Combining the statistics of all measurements and the evolution of individual bursts, we find that a typical sequence for intense events begins with rapid strain growth, followed by rising vorticity and a final sudden decline in stretching. We suggest two mechanisms which can produce these characteristics, depending whether they are due to the advection of coherent structures through our observed volume or caused locally.
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U2 - 10.1038/nature01334
DO - 10.1038/nature01334
M3 - Article
C2 - 12520296
AN - SCOPUS:0037426874
SN - 0028-0836
VL - 421
SP - 146
EP - 149
JO - Nature
JF - Nature
IS - 6919
ER -