American Physical Society;United States: American Physical Society (APS)
摘要:
摘要： We experimentally investigate the self-propelled two-dimensional turbulent flows of Escherichia coli suspensions in thin liquid films at two different cell concentrations. It is found that the flow has fluctuating vortices with a broad range of scales and intensities through the nonlinear interaction of the swimming bacteria. Increasing cell concentration increases the total propelling power and the nonlinear interaction. It causes the generation of vortices with larger scale, lower frequency, and higher intensity. It also widens the histograms of the flow velocity and the velocity increment between two spatially separated points with more stretched non-Gaussian tails. From the scaling analysis of the structure function S(q)(r) of the qth moment of the velocity increment between two points with spatial separation r, nonlinear relations between the scaling exponent ζ(q) of S(q)(r) and q are found for both cell concentrations, which manifests the multifractal dynamics. The multifractality can be enhanced by increasing cell concentration. 其他題名： Phys Rev E Stat Nonlin Soft Matter Phys 出版者： United States: American Physical Society (APS) 出版日期： 2012-07-24 出處： Physical Review E, 2012-07, Vol.86 (1), p.011924, Article 011924 識別號： ISSN: 1539-3755 識別號： ISSN: 1550-2376 識別號： EISSN: 1550-2376 識別號： DOI: 10.1103/physreve.86.011924 識別號： PMID: 23005469
