Fluid motions are used to be complex as a result of instability and turbulence. However, in the statistical sense, the fluid motion has a particular pattern, consists of the small- and large-scale motions. Investigation of the pattern itself (i.e., flow structure) and the relationship to the flow statistics is important to improve the modeling of the nonlinear flow behavior and to understand the nature. To simplify the information in the flow fields, the algorithm for detecting the large-scale motions is devised.

• Development of the streak detection method to investigate the large-scale turbulent structures statistically

• Identification of the structures in the 3-D instantaneous flow fields

  1. Turbulent/non-turbulent interface

  2. Large-scale coherence of velocity fluctuations, vorticity and/or the Reynolds stress

• Tracking of the detected structures with time

• Sorting of the detected structures by the spatial dimension

• Related papers: Lee & Zaki (C&F 2018), Lee et al. (JFM 2014, PoF 2015), Hwang et al. (JFM 2016)

• Vorticity magnitude as a detector function

• Normalization for the Reynolds-number independent detection

• Related paper: Lee & Zaki (C&F 2018), Lee et al. (JFM 2017)