Velocity gradient partitioning in turbulent flows
Abstract
The velocity gradient tensor can be decomposed into normal straining, pure shearing and rigid rotation tensors, each with distinct symmetry and normality properties. We partition the strength of turbulent velocity gradients based on the relative contributions of these constituents in several canonical flows. These flows include forced isotropic turbulence, turbulent channels and turbulent boundary layers. For forced isotropic turbulence, the partitioning is in excellent agreement with previous results. For wall-bounded turbulence, the partitioning collapses onto the isotropic partitioning far from the wall, where the mean shearing is relatively weak. By contrast, the near-wall partitioning is dominated by shearing. Between these two regimes, the partitioning collapses well at sufficiently high friction Reynolds numbers and its variations in the buffer layer and the log-law region can be reasonably modelled as a function of the mean shearing strength. Altogether, our results highlight the expressivity and broad applicability of the velocity gradient partitioning as advantages for turbulence modelling.
Copyright and License
© The Author(s), 2024. Published by Cambridge University Press.
Acknowledgement
The authors gratefully acknowledge the reviewers for helpful feedback, A. Nekkanti and M. Wadas for discussions and H.J. Bae for providing the Ch0186 dataset.
Funding
R.A. was supported by the Department of Defense (DoD) through the National Defense Science & Engineering Graduate (NDSEG) Fellowship Program.
Data Availability
Sample code for computing the velocity gradient partitioning is available at https://doi.org/10.22002/17h15-gr910.
Additional details
- United States Department of Defense
- National Defense Science & Engineering Graduate (NDSEG) Fellowship Program
- Accepted
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2024-10-20Accepted
- Available
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2024-12-03Published online
- Caltech groups
- GALCIT
- Publication Status
- Published