Large-scale motions from a direct numerical simulation of a turbulent boundary layer

TL;DR

This paper investigates large-scale motions in a turbulent boundary layer using direct numerical simulation data up to Reθ ~ 2500, analyzing their structure, size, and statistical properties.

Contribution

It introduces a novel skeletonization method to extract and analyze large-scale structures in turbulent boundary layers from DNS data.

Findings

Structures up to 10 boundary layer thickness observed.

Streamwise length distribution follows a -2 power law.

Large structures exhibit similar statistical properties to experimental results.

Abstract

A study of large-scale motions from a new direct numerical simulation database of the turbulent boundary layer up to Re{\theta} ~ 2500 is presented. The statistics of large-scale streamwise structures have been investigated using two-dimensional and three-dimensional extraction procedures. The large-scale structures are abstracted using a robust skeletonization method usually applied to other research domains to simplify complex 3D objects. Different structure parameters such as the length, shape or angle are investigated. The features of the detected structures are compared to their mean counterparts extracted from two-point correlations. Structures as large as 10 boundary layer thickness are observed. The streamwise length of these structures follows a -2 power law distribution, similar to the experimental findings at higher Reynolds numbers.