On the detection of internal interfacial layers in turbulent flows

Abstract

A novel approach to identify internal interfacial layers, or IILs, in wall-bounded turbulent flows is proposed. Using a Fuzzy Cluster Method (FCM) on the streamwise velocity component, a unique and unambiguous grouping of the Uniform Momentum Zones is achieved, thus allowing the identification of the IILs. The approach overcomes some of the key limitations of the histogram-based IIL identification methods. The method is insensitive to the streamwise domain length, can be used on inhomogeneous grids, uses all the available flow field data, is trivially extended to three dimensions, and does not need user-defined parameters (e.g. number of bins) other than the number of zones\add{. The number of zones can be automatically determined by an \emph{a priori} algorithm based on a Kernel Density Estimation algorithm, or KDE.} The clustering approach is applied to the turbulent boundary layer (experimental, planar PIV) and channel flow (numerical, DNS) \add{at varying Reynolds numbers}. \modify{The interfacial layers are characterized by a strong concentration of spanwise vorticity, with the outer-most layer located at the upper edge of the log-layer. The three-dimensional interface identification reveals a streak-like organization; we show that the organization of the IILs is correlated to the underlying wall-bounded turbulent structures. }

References in corpus (2)

• Direct numerical simulation of turbulent channel flow up to $R{e}_{\tau }\approx 5200$
• Properties of the turbulent/non-turbulent interface in boundary layers

Cited by in corpus (6)

• Objective Momentum Barriers in Wall Turbulence
• Turbulence organization and mean profile shapes in the stably stratified boundary layer: zones of uniform momentum and air temperature
• Self-similar geometries within the inertial subrange of scales in boundary layer turbulence
• Stochastic modelling of the instantaneous velocity profile in rough-wall turbulent boundary layers
• Coherent Structures Governing Transport at Turbulent Interfaces
• A self-sustaining process theory for uniform momentum zones and internal shear layers in high Reynolds number shear flows