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Updated: Jul 6, 2026
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Experimental Investigation of Secondary Flow Structures Downstream of a Model Type IV Stent Failure in a 180° Curved Artery Test Section
Published on: July 19, 2016
Local and nonlocal strain rate fields and vorticity alignment in turbulent flows
Peter E Hamlington1, Jörg Schumacher, Werner J A Dahm
1Laboratory for Turbulence & Combustion (LTC), Department of Aerospace Engineering, The University of Michigan, Ann Arbor, Michigan 48109-2140, USA. peterha@umich.edu
Summary
This study introduces a method to separate local and nonlocal strain rate contributions in turbulent flows. It reveals how vorticity aligns with the background strain rate, improving understanding of turbulent structures.
Area of Science:
- Fluid Dynamics
- Turbulence Research
- Computational Physics
Background:
- Understanding turbulent flows requires distinguishing local and nonlocal strain rate contributions.
- Vorticity alignment with strain rate is crucial for characterizing turbulent structures.
- Previous methods struggled to accurately isolate background strain effects.
Purpose of the Study:
- To develop an exact expression for the nonlocal (background) strain rate tensor.
- To analyze the alignment of vorticity with the principal axes of the background strain rate tensor.
- To investigate the role of viscous length scale in determining expansion parameters.
Main Methods:
- Formulating strain rate tensor contributions via vorticity field expansion in a local spherical neighborhood.
- Utilizing an equilibrium Burgers vortex to demonstrate convergence of the background strain rate field.
- Applying direct numerical simulations of homogeneous isotropic turbulence.
Main Results:
- An exact expression was derived to obtain the nonlocal strain rate tensor from the total strain rate tensor.
- The method resolves the anomalous alignment of vorticity with the intermediate eigenvector of the total strain rate tensor.
- In simulations, increased alignment of vorticity with the most extensional principal axis of the background strain rate tensor was observed.
Conclusions:
- The developed method accurately isolates background strain rate effects in turbulent flows.
- This approach enhances the understanding of vorticity alignment within turbulent structures.
- The findings have implications for modeling and predicting turbulent phenomena.
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