Flow structures in zero pressure-gradient turbulent boundary layers at high Reynolds numbers

Application of Liquid Crystal Thermography for the investigation of the near-wall coherent structures in a turbulent boundary layer

“…In the plot U + c = U c /u . The estimated value of the convection velocity is found to be 0.084 m/s, equivalent to 13-14 u , in agreement with the results obtained by Osterlund and Jeon [10,7].…”

Turbulence and turbulent flux events in a small estuary

“…While this approach differs from more traditional event detection techniques (e.g. [2,13,21]), it was found herein to be a robust method well-suited to the study of the unsteady estuary flow. A turbulent event is basically defined as a series of turbulent fluctuations that contain more energy than the average turbulent fluctuations within a studied data section.…”

“…But a complete characterisation of turbulence encompasses (a) the spatial distribution of Reynolds stresses, and also (b) the rates at which the individual Reynolds stresses are produced, destroyed or transported from one point in space to another, (c) the contribution of different sizes of eddy to the Reynolds stresses, and (d) the contribution of different sizes of eddy to the rates mentioned in (b) and to rate at which Reynolds stresses are transferred from one range of eddy size to another ( [3]). It is argued herein that a turbulent event analysis is a simpler approach, as demonstrated by seminal turbulence studies including [1,2,13,17,19] and [21]. Turbulent events and sub-events were investigated for the turbulent fluxes v x v z , v x v y , and v x i b , using the data collected by the ADV1, ADV2 and ADV3 units.…”

“…There have been many progresses in their physical description in laboratory and in the field. Turbulent event analyses were successfully applied to laboratory open channel flows [17,19], wind tunnel studies [21] and atmospheric boundary layer flows [10,18]. They were however rarely applied to unsteady open channel flows and estuaries.…”

Direct numerical simulation of convective heat transfer in a zero-pressure- gradient boundary layer with supercritical water

“…The spanwise extent of the largest coherent flow structures in the boundary layer are of O(δ), and take the form of streamwise-aligned wave-packets of hairpin-like vortical structures in the outer region of the boundary layer. These structures form through spanwise merging of near-wall vortex loops that have a spanwise spacing of Δz + ≈100 [10][11][12]. However, to accurately capture the structures in the inner part of the boundary layer, a computational-domain span greater than 220 wall units must be used [9].…”