Topological Characteristics of Coherent Structures in the Turbulent Boundary Layer Measured by Tomo-PIV

Abstract:

Database of time series of the instantaneous three-dimensional three-component (3D-3C) velocity vector field, measured by tomographic time-resolved PIV(Tomo-PIV) in a water tunnel, was analyzed to investigate spatial topologies of coherent structures in the turbulent boundary layer (TBL). A new concept of spatial locally averaged velocity structure function of turbulence is put forward to describe the spatial dilation or compression of the multi-scale coherent structures in the TBL. According to the physical mechanism of dilation or compression of multi-scale coherent vortex structures in the turbulent flow, a new conditional sampling method was proposed as well to extract the spatial topological characteristics of physical quantities of coherent structures, such as fluctuating velocities, velocity gradients, velocity strain rates and vorticity during the bursting process in the Tomo-PIV database. Furthermore, the anti-symmetric structures are the typical spatial topologies characteristics for the velocity gradients and vorticity during coherent structures burst.

• Periodical: Advanced Materials Research (Volumes 718-720)
• Pages: 801-806
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.718-720.801
• Online since: July 2013
• Authors: Hai Ping Tian, Shao Qiong Yang, Nan Jiang
• Keywords: Anti-Symmetric Structures, Coherent Structure, Tomo-PIV, Turbulent Boundary Layer

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