Direct numerical simulation of the very large anisotropic scales in a turbulent channel

TL;DR

This paper presents a preliminary numerical database of very large anisotropic scales in turbulent channel flow at moderate Reynolds numbers, addressing a previously challenging aspect of turbulence simulation.

Contribution

It introduces a newly compiled numerical database focusing on the large scales in turbulent channel flow, expanding understanding beyond small-scale turbulence.

Findings

Large scales are significant in turbulent channel flow.

Numerical database enables detailed analysis of large-scale turbulence.

Simulation at moderate Reynolds numbers is now feasible for large scales.

Abstract

Over the last decades the knowledge on the small scales of turbulent wall flows has experienced a significant advance, especially in the near-wall region where the highest production of turbulent energy and the maximum turbulence intensity occur. The development of computers has played an important role in this progress, making direct numerical simulations affordable (Kim, Moin & Moser, 1987), and offering wider observational possibilities than most laboratory experiments. The large scales have received less attention, and it has not been until recently that their significance and their real size have been widely recognized, thanks in part to the experiments by Hites (1997) and Kim & Adrian (1999), and to the compilation of experimental and numerical data by Jimenez (1998). The requirements of both a very large box and a high Reynolds number has made direct numerical simulation of the VLAS unapproachable until today. The purpose of this report is to serve as a preliminary description of a newly compiled numerical database of the characteristics of the large scales in turbulent channel flow at moderate Reynolds numbers.