Direct numerical simulation of a turbulent boundary layer up to Re-theta=2500

Abstract

Direct numerical simulations (DNSs) of a turbulent boundary layer (TBL) with Re-theta = 570-2560 were performed to investigate the spatial development of its turbulence characteristics. The inflow simulation was conducted in the range Re-theta = 570-1600 by using Lund's method. To resolve the numerical periodicity induced by the recycling method, we adopted a sufficiently long streamwise domain of x/theta(in.i) = 1000 (=1256 delta(o,i)), where theta(in.i) is the inlet momentum thickness and delta(o.i) is the inlet boundary layer thickness in the inflow simulation. Furthermore, the main simulation with a length greater than 50 delta(o) was carried out independently by using the inflow data, where delta(o) is the inlet boundary layer thickness of the main simulation. The integral quantities and the first-, second- and higher-order turbulence statistics were compared with those of previous data, and good agreement was found. The present study provides a useful database for the turbulence statistics of TBLs. In addition, instantaneous field and two-point correlation of the streamwise velocity fluctuations displayed the existence of the very large-scale motions (VLSMs) with the characteristic widths of 0.1-0.2 delta and that the flow structure for a length of approximately similar to 6 delta fully occupies the streamwise domain statistically. (c) 2010 Elsevier Inc. All rights reserved.