Three‐Dimensional Representation of Large‐Scale Structures Based on Observations in Atmospheric Surface Layers

Abstract

Large amounts of synchronous multipoint measurement data were acquired from long‐term observations in high‐Reynolds‐number atmospheric surface layers (Reτ∼O(106)) at the Qingtu Lake observation array site. Based on these experimental data, the general shapes of three‐dimensional (3‐D) large‐scale coherent structures are constructed coupled with the symmetry of two‐point streamwise velocity correlations in the spanwise direction, where the spanwise symmetry is confirmed to be applicable in the atmospheric surface layer flow by experimental verification. The full extent of the 3‐D structure is much larger than a 2‐D slice at the condition point and increases significantly with the reference height in the logarithmic region. Moreover, the streamwise length and the spanwise width of the horizontal section are found to vary systematically with the relative height to the condition point. These variations are parametrized and can subsequently be used to infer the horizontal section at different relative heights. Then, a plausible empirical model is proposed by taking into consideration the streamwise shift caused by the inclination angle, and the 3‐D structure can be predicted by this model using the primary flow parameters and location information. This study contributes to a better understanding of dominant structures in the outer region of wall turbulence at high Reynolds numbers.

High-frequency observation during sand and dust storms at the Qingtu Lake Observatory

“…(i) The canonical atmospheric turbulent boundary layer is the near-neutral atmospheric surface layer that can be viewed as a truly high-Reynolds-number facility (Re τ = δu τ /ν = O(10 6 ), where δ is the boundary layer thickness, u τ is the skin-friction velocity and ν is the kinematic viscosity). Characteristics of coherent structures were investigated under near-neutral and stratified conditions (e.g., Wang and Zheng, 2016;Liu et al, 2019;Li and Bo, 2019a;Li et al, 2021b). Roughness effects were explored to illustrate the features in the near-surface layer (e.g., Li and Bo, 2019b;Li et al, 2021c).…”

Large-scale structures of wall-bounded turbulence in single- and two-phase flows: advancing understanding of the atmospheric surface layer during sandstorms

“…The observation array in the streamwise direction facilitates the measurement of the streamwise length scale of the VLSMs in the ASL and accordingly provides the error and applicability of Taylor's hypothesis in estimating the scale of the VLSMs. Moreover, these three-dimensional ASL observations are helpful for inverting the spatial structures of the flow field (see the paper by (Liu, Wang, and Zheng, 2019a), in which a plausible empirical model was proposed to characterize the general shape of the three-dimensional large log-layer structure), dust concentration and electric field.…”

“…The observation array in the streamwise direction facilitates the measurement of the streamwise length scale of the VLSMs in the ASL and accordingly provides the error and applicability of Taylor's hypothesis in estimating the scale of the VLSMs. Moreover, these three-dimensional ASL observations are helpful for inverting the spatial structures of the flow field (see the paper by (Liu, Wang, and Zheng, 2019a), in which a plausible empirical model was proposed to characterize the general shape of the three-dimensional large log-layer structure), dust concentration and electric field. To achieve the high-frequency synchronous measurement of multiple physical quantities, the QLOA is equipped with various measuring equipment, such as sonic anemometers (Gill Instruments R3-50 and Campbell CSAT3B) operating at a sampling frequency of 50 Hz, aerosol monitors (TSI, DUST TRAK II-8530-EP), temperature sensors and three-dimensional vibrating-reed electric field mills (VREFMs).…”

High frequency observation during the sand and dust storms in the Qingtu Lake Observatory

“…Precious works where the data were collected at the current site can be categorized by three series: i) Canonical atmospheric turbulent boundary layer: The near-neutral atmospheric surface layer can be viewed as a truly high-Reynolds-number facility (Re τ = δu τ /ν = O(10 6 ), where δ is the boundary layer thickness, u τ is the skin-friction velocity and ν is the kinematic viscosity). Characteristics of coherent structures were investigated under near-neutral and stratified conditions (e.g., Wang and Zheng, 2016;Liu et al, 2019;Li and Bo, 2019a;Li et al, 2021b). Roughness effects were explored to illustrate the features in the near surface layer (e.g., Li and Bo, 2019b;Li et al, 2021c).…”