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Properties of the curvature tensor of streamtubes in turbulent flows

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Important features of the shape of streamtubes can be described by the first and second invariant of the curvature tensor ∂ti/∂xj where t is the unit vector tangent to the streamlines forming the tube. In three-dimensional turbulence, three different generic behaviors can be found, as well as four degenerate cases. For instance, the first invariant of t represents the relative change of the tube’s cross-section. The joint PDF of the first and second invariant is evaluated from DNS, and the results stemming from the presented classification scheme are discussed. An attempt to reproduce the observed PDF from a restricted-Euler like model is described.

Author(s):

Jonas Boschung    
Institute for Combustion Technology, RWTH Aachen University
Germany

Charles Meneveau    
Department of Mechanical Engineering & Center for Environmental and Applied Fluid Mechanics, Johns Hopkins University
United States

Norbert Peters    
Institute for Combustion Technology, RWTH Aachen University
Germany