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Updated: Jan 5, 2026
08:01
The Diffusion of Passive Tracers in Laminar Shear Flow
Published on: May 1, 2018
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A hierarchical random additive model for passive scalars in wall-bounded flows at high Reynolds numbers
Xiang I A Yang1,2, Mahdi Abkar1,3
1Center for Turbulence Research, Stanford University, Stanford, CA 94305, USA.
Journal of Fluid Mechanics
|October 22, 2019
Summary
The hierarchical random additive process (HRAP) model successfully describes passive scalar turbulence. This framework extends HRAP
Area of Science:
- Fluid Dynamics
- Turbulence Modeling
- Scalar Transport
Background:
- Passive scalar turbulence in wall-bounded flows is complex.
- The hierarchical random additive process (HRAP) formalism offers a new interpretation of the Townsend attached eddy hypothesis.
- Previous HRAP models successfully described velocity fluctuations in wall turbulence.
Purpose of the Study:
- To model the kinematics of fully developed passive scalars using the HRAP formalism.
- To investigate if HRAP, successful for velocity, can also model scalar fluctuations.
- To establish a framework for scalar turbulence modeling in high Reynolds number wall-bounded flows.
Main Methods:
- Application of the hierarchical random additive process (HRAP) formalism to passive scalar fields.
- Leveraging generalized logarithmic scalings observed in velocity fluctuations for scalar fields.
- Validation using large-eddy simulations (LES) of turbulent flows.
Main Results:
- The HRAP model successfully predicts generalized logarithmic scalings for passive scalar fluctuations.
- HRAP accurately models the kinematics of passive scalars, mirroring findings in velocity fluctuations.
- Large-eddy simulations confirm the applicability of the HRAP model to scalar turbulence.
Conclusions:
- The HRAP formalism provides a robust framework for modeling passive scalar turbulence.
- The study confirms the similarity in statistical behaviors between velocity and passive scalar fluctuations.
- This work advances the understanding and modeling of scalar transport in high Reynolds number wall-bounded flows.
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