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Small-scale averaging coarse-grains passive scalar turbulence

Title data

Bätge, Tobias ; Wilczek, Michael:
Small-scale averaging coarse-grains passive scalar turbulence.
In: Physical Review Fluids. Vol. 6 (2021) Issue 6 . - No. 064503.
ISSN 2469-990X
DOI: https://doi.org/10.1103/PhysRevFluids.6.064503

Abstract in another language

Scalar fields which are subject to turbulent mixing typically feature a broad range of scales. When focusing on the large-scale dynamics, it remains a question how to effectively parametrize the small scales. Here, we address this question within the framework of a stochastic, one-dimensional passive scalar model. We show that small-scale averaging, i.e., an ensemble average over small-scale velocity fluctuations, results in an effective diffusivity reminiscent of phenomenological eddy viscosity models, while reducing the effective Reynolds number of the advecting velocity field. Based on that, we establish a filtering procedure that exactly maps second-order statistics of the fully resolved passive scalar field to the one obtained by small-scale averaging. Using fully resolved simulations, we show that small-scale averaging also captures higher-order large-scale statistics of passive scalar fields.

Further data

Item Type: Article in a journal
Refereed: Yes
Institutions of the University: Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Physics > Chair Theoretical Physics I > Chair Theoretical Physics I - Univ.-Prof. Dr. Michael Wilczek
Profile Fields > Advanced Fields > Nonlinear Dynamics
Result of work at the UBT: No
DDC Subjects: 500 Science > 530 Physics
Date Deposited: 23 Feb 2022 12:59
Last Modified: 23 Feb 2022 12:59
URI: https://eref.uni-bayreuth.de/id/eprint/67587