Evidence for the existence of eddy-structure in fine-scale turbulence

Dale Pullin, Graduate Aeronautical Laboratories, California Institute of Technology, USA

Literature research aimed at exploring the geometric structure of turbulence using detailed experimentation and direct numerical simulation will be reviewed with emphasis on the fine scales in the inertial and dissipation ranges. Methodologies based on local measures of fields obtained from the velocity gradient tensor, the rotation tensor, their various products, and the pressure field will be discussed. These and other classification schemes for the identification of vortex tube-like, sheet-like, blob-like and other geometric eddy structures will be outlined. We will then consider recent work on the detection, characterization and classification of scalar and vortex structures in turbulence using non-local, geometrical and statistical approaches. Methods based on analysis of isosurfaces within large volume data sets using wavelet decomposition and the multi-scale curvelet transform will be discussed in the context of conceptual models for sheet, tube, blob and other geometrical shape constructs.