A analysis workforce from the Institute of Mechanics of the Chinese language Academy of Sciences has revealed the multi-scale traits of helicity in wall-bounded turbulent flows.
Helicity is a second-order inviscid invariant in three-dimensional turbulence, which performs a key function within the evolution of turbulent programs. The analysis on the fundamental principle of helicity is necessary to enhance the efficiency of the aero-engine, fuel turbine and different key gear.
Up to now few a long time, the helicity impact was primarily used to discover the inner mechanism of turbulence, however the statistical properties of helicity in turbulence, particularly anisotropic turbulence, had been hardly ever studied.
On this examine, the researchers investigated the helicity statistics in turbulent channel flows with streamwise rotation at average rotation numbers and Reynolds numbers, together with their spatial and scale distributions, anisotropy and cross-scale switch.
They prolonged the helical turbulence principle from homogeneous and isotropic turbulent flows to wall-bounded turbulent flows. They discovered a brand new peak of helicity inside the near-wall areas, which corresponded to an obvious scale separation of helicity distribution.
The outcomes additionally confirmed that nonlinear interactions of various scales had been sturdy sufficiently to maintain the broadband helicity spectra. Numerical penalties indicated that helicity cascade in wall-bounded turbulent flows was dominated by the vortex stretching course of.
These findings will present a vital theoretical foundation for extra advanced analysis on rotating wall turbulence principle and utility know-how.
The examine was printed in Journal of Fluid Mechanics.
Changping Yu et al, Helicity distributions and switch in turbulent channel flows with streamwise rotation, Journal of Fluid Mechanics (2022). DOI: 10.1017/jfm.2022.250
Chinese language Academy of Sciences
Researchers reveal multi-scale traits of helicity in wall-bounded turbulent flows (2022, Might 19)
retrieved 19 Might 2022
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