TY - JOUR
T1 - Characteristics of shearing motions in incompressible isotropic turbulence
AU - Watanabe, T.
AU - Tanaka, K.
AU - Nagata, K.
N1 - Funding Information:
The authors would like to thank Prof. C. B. da Silva for discussion on the triple decomposition of three-dimensional velocity gradient tensors. This work was supported by JSPS KAKENHI Grants No. 18K13682, No. 18H01367, and No. 19J12973 and by “Collaborative Research Project on Computer Science with High-Performance Computing in Nagoya University.” Some of the numerical simulations presented in this Rapid Communication were carried out on the high-performance computing system (NEC SX-ACE) at the Japan Agency for Marine-Earth Science and Technology.
Funding Information:
The authors would like to thank Prof. C. B. da Silva for discussion on the triple decomposition of three-dimensional velocity gradient tensors. This work was supported by JSPS KAKENHI Grants No. 18K13682, No. 18H01367, and No. 19J12973 and by ?Collaborative Research Project on Computer Science with High-Performance Computing in Nagoya University.? Some of the numerical simulations presented in this Rapid Communication were carried out on the high-performance computing system (NEC SX-ACE) at the Japan Agency for Marine-Earth Science and Technology.
Publisher Copyright:
© 2020 American Physical Society.
PY - 2020/7
Y1 - 2020/7
N2 - Regions with shearing motions are investigated in isotropic turbulence with the triple decomposition, by which a velocity gradient tensor is decomposed into three components representing an irrotational straining motion, a rotating motion, and a shearing motion. A mean flow around the shearing motions shows that a thin shear layer is sustained by a biaxial strain, which is consistent with Burgers' vortex layer. The thickness of each shear layer is well predicted by Burgers' vortex layer. A comparison between genuine turbulence and a random velocity field confirms that the biaxial strain acting on the shear is a dynamical consequence from the Navier-Stokes equations rather than from a kinematic relation. The interplay between the shear and biaxial strain causes enstrophy production and strain self-amplification. For a wide range of Reynolds number, the shear is strong enough for the instability to cause a roll-up of the shear layer, where the perturbation grows much faster than large-scale turbulent motions.
AB - Regions with shearing motions are investigated in isotropic turbulence with the triple decomposition, by which a velocity gradient tensor is decomposed into three components representing an irrotational straining motion, a rotating motion, and a shearing motion. A mean flow around the shearing motions shows that a thin shear layer is sustained by a biaxial strain, which is consistent with Burgers' vortex layer. The thickness of each shear layer is well predicted by Burgers' vortex layer. A comparison between genuine turbulence and a random velocity field confirms that the biaxial strain acting on the shear is a dynamical consequence from the Navier-Stokes equations rather than from a kinematic relation. The interplay between the shear and biaxial strain causes enstrophy production and strain self-amplification. For a wide range of Reynolds number, the shear is strong enough for the instability to cause a roll-up of the shear layer, where the perturbation grows much faster than large-scale turbulent motions.
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U2 - 10.1103/PhysRevFluids.5.072601
DO - 10.1103/PhysRevFluids.5.072601
M3 - Article
AN - SCOPUS:85092220913
SN - 2469-990X
VL - 5
JO - Physical Review Fluids
JF - Physical Review Fluids
IS - 7
M1 - 072601
ER -