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Vortex-to-velocity reconstruction for wall-bounded turbulence via the field-based linear stochastic estimation

Published online by Cambridge University Press:  12 July 2021

Chengyue Wang Open the ORCID record for Chengyue Wang [Opens in a new window] ,
Qi Gao Open the ORCID record for Qi Gao [Opens in a new window] ,
Biao Wang ,
Chong Pan  and
Jinjun Wang Open the ORCID record for Jinjun Wang [Opens in a new window]
Chengyue Wang
Affiliation:
Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-sen University, Zhuhai 519082, PR China Fluid Mechanics Key Laboratory of Education Ministry, Beijing University of Aeronautics and Astronautics, Beijing 100191, PR China
Qi Gao*
Affiliation:
School of Aeronautics and Astronautics, Zhejiang University, Hangzhou 310027, PR China Fluid Mechanics Key Laboratory of Education Ministry, Beijing University of Aeronautics and Astronautics, Beijing 100191, PR China
Biao Wang*
Affiliation:
Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-sen University, Zhuhai 519082, PR China
Chong Pan
Affiliation:
Fluid Mechanics Key Laboratory of Education Ministry, Beijing University of Aeronautics and Astronautics, Beijing 100191, PR China
Jinjun Wang
Affiliation:
Fluid Mechanics Key Laboratory of Education Ministry, Beijing University of Aeronautics and Astronautics, Beijing 100191, PR China
*
† Email addresses for correspondence: qigao@zju.edu.cn, wangbiao@mail.sysu.edu.cn
† Email addresses for correspondence: qigao@zju.edu.cn, wangbiao@mail.sysu.edu.cn
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Abstract

Representing complex flows by evolving vortex structures is an important principle in many investigations of wall-bounded turbulence. The practice of this principle benefits from the bi-directional transformation between the velocity field and the corresponding vortex field. While the velocity-to-vortex transformation could be implemented by various vortex identification criteria, few efforts have been devoted to the inverse process. This work develops a linear reconstruction method, which allows an effective reconstruction for the velocity field of wall turbulence based on a given vortex field. The vortex field is defined as a vector field by combining the swirl strength and the real eigenvector of the velocity gradient tensor. The reconstructed velocity fields are calculated by convolution operations on the vortex fields, with the kernel functions derived by the field-based linear stochastic estimation. The method can effectively recover the turbulent motions in a large scale range, showing clear advantages over the Biot–Savart formula in the near-wall region. The method is also employed to investigate the inducing effects of vortices at different heights. The wall-bounding effect on the induced motions is observed from the contribution spectra of vortices. The higher-order moments of the reconstructed streamwise velocity component present larger deviations from the original data, which is discussed and explained reasonably. At last, the vortex fields filtered by prescribed thresholds are employed to reconstruct the velocity fields. It is found that the strongest vortex components occupying 5 % of the total volume can reasonably recover the main flow features including both the near-wall streaks and the large-scale motions.

JFM classification

Boundary Layers: Boundary layer structure Turbulent Flows: Turbulent boundary layers Vortex Flows: Vortex dynamics

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JFM Papers
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Journal of Fluid Mechanics , Volume 922 , 10 September 2021 , A18
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© The Author(s), 2021. Published by Cambridge University Press

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