TY - JOUR
T1 - Small-Scale Isotropy and Ramp-Cliff Structures in Scalar Turbulence
AU - Buaria, Dhawal
AU - Clay, Matthew P.
AU - Sreenivasan, Katepalli R.
AU - Yeung, P. K.
N1 - Funding Information:
We thank Kartik Iyer and Jörg Schumacher for useful discussions. This research used resources of the Oak Ridge Leadership Computing Facility (OLCF), which is a Department of Energy (DOE) Office of Science user facility supported under Contract No. DE-AC05-00OR22725. We acknowledge the use of advanced computing resources at the OLCF under INCITE Awards. Parts of the data analyzed in this work were obtained through National Science Foundation (NSF) Grant No. ACI-1036170, using resources of the Blue Waters sustained petascale computing project, which was supported by the NSF (Grants No. OCI-725070 and No. ACI-1238993) and the State of Illinois. D. B. also gratefully acknowledges the Gauss Centre for Supercomputing e.V. for providing computing time on the supercomputer JUWELS at Jülich Supercomputing Centre, where the simulations were performed.
Publisher Copyright:
© 2021 American Physical Society.
PY - 2021/1/22
Y1 - 2021/1/22
N2 - Passive scalars advected by three-dimensional Navier-Stokes turbulence exhibit a fundamental anomaly in odd-order moments because of the characteristic ramp-cliff structures, violating small-scale isotropy. We use data from direct numerical simulations with grid resolution of up to 8192^{3} at high Péclet numbers to understand this anomaly as the scalar diffusivity, D, diminishes, or as the Schmidt number, Sc=ν/D, increases; here ν is the kinematic viscosity of the fluid. The microscale Reynolds number varies from 140 to 650 and Sc varies from 1 to 512. A simple model for the ramp-cliff structures is developed and shown to characterize the scalar derivative statistics very well. It accurately captures how the small-scale isotropy is restored in the large-Sc limit, and additionally suggests a possible correction to the Batchelor length scale as the relevant smallest scale in the scalar field.
AB - Passive scalars advected by three-dimensional Navier-Stokes turbulence exhibit a fundamental anomaly in odd-order moments because of the characteristic ramp-cliff structures, violating small-scale isotropy. We use data from direct numerical simulations with grid resolution of up to 8192^{3} at high Péclet numbers to understand this anomaly as the scalar diffusivity, D, diminishes, or as the Schmidt number, Sc=ν/D, increases; here ν is the kinematic viscosity of the fluid. The microscale Reynolds number varies from 140 to 650 and Sc varies from 1 to 512. A simple model for the ramp-cliff structures is developed and shown to characterize the scalar derivative statistics very well. It accurately captures how the small-scale isotropy is restored in the large-Sc limit, and additionally suggests a possible correction to the Batchelor length scale as the relevant smallest scale in the scalar field.
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U2 - 10.1103/PhysRevLett.126.034504
DO - 10.1103/PhysRevLett.126.034504
M3 - Article
C2 - 33543985
AN - SCOPUS:85099882039
SN - 0031-9007
VL - 126
JO - Physical Review Letters
JF - Physical Review Letters
IS - 3
M1 - 034504
ER -