Cascade of turbulent energy and scalar variance in DC electrokinetic turbulence

PHYSICA D-NONLINEAR PHENOMENA

卷:399

Article

Zhao, Wei^1,2  Wang, Guiren^1,2,3 

[1] Northwest Univ, Inst Photon & Photon Technol, Int Sci & Technol Cooperat Base Photoelect Techno, Xian, Shaanxi, Peoples R China

[2] Univ South Carolina, Dept Mech Engn, Columbia, SC 29208 USA

[3] Univ South Carolina, Biomed Engn Program, Columbia, SC 29208 USA

关键词: Direct current;    Electrokinetic turbulence;    Kinetic energy transport;    Scalar transport;    Scaling law;   

DOI  :  10.1016/j.physd.2019.04.003

来源: Elsevier

【 摘 要 】

Turbulent flow can be generated by DC electrokinetic (EK) mechanism resulted from the electric conductivity and permittivity variation in fluids, as has been demonstrated by Varshney et al (2016), where a -1.4 slope of velocity power spectrum is observed. Here, we theoretically investigate the scaling exponents of both velocity and scalar structure functions in DC EK turbulence. The scaling exponents of the second order structure functions of velocity and scalar in the so-called electric body force (EBF) dominant subrange are 2/5 (equivalent to the -7/5 slope of velocity power spectrum) and 4/5 respectively. The theory directly explains the experimental results of Varshney et al. (2016). Based on Karman-Howarth equation with forcing terms, the third order structure function of velocity which is the representative of energy transport process is investigated in the DC EK turbulence. Compared with the conventional hydrodynamic turbulence, the energy transport in DC EK turbulence has an additional scaling subrange and is governed by additional small length scales. (C) 2019 Elsevier B.V. All rights reserved.

【 授权许可】

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