2024-03-03T07:57:06Z
https://nagoya.repo.nii.ac.jp/oai
oai:nagoya.repo.nii.ac.jp:00027161
2023-01-16T04:45:49Z
673:674:675
No return to reflection symmetry in freely decaying homogeneous turbulence
Yoshimatsu, Katsunori
89018
Kaneda, Yukio
89019
We consider the large-scale structure of freely decaying incompressible homogeneous anisotropic helical turbulence, whose energy spectrum E(k) is given by E(k)=Ck^2+o(k^2) at k→0. Here k=|k|,k is the wave vector, and C is a dynamical invariant. The helicity spectrum H(k) is given by H(k)=Chk^3+o(k^3) at k→0, where Ch is in general nonzero in helical turbulence. By generalizing Saffman's argument for nonhelical turbulence [Saffman, J. Fluid Mech. 27, 581 (1967)] to helical turbulence, it is shown that Ch is another dynamical invariant. We present a theoretical analysis based on the time independence of the O(k^0) term of the velocity correlation spectral tensor at k→0 and a self-similarity assumption of flow evolution at large scales including the energy containing range scales. The analysis suggests that if the O(k^0) term is reflection asymmetric at an initial instant, the turbulence does not relax to any reflection symmetric state at the large scales. A simple dimensional analysis yields the decay rates of the helicity and kinetic energy in the fully developed turbulence state. The theoretical results agree with results obtained by direct numerical simulation of incompressible helical turbulence in a periodic box.
journal article
American Physical Society
2019-02-27
application/pdf
Physical Review Fluids
2
4
024611
2469-990X
https://nagoya.repo.nii.ac.jp/record/27161/files/PhysRevFluids4_024611.pdf
eng
https://doi.org/10.1103/PhysRevFluids.4.024611
© 2019 American Physical Society