Gusty wind disturbances and large-scale turbulent structures in the neutral atmospheric surface layer

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

“…According to the analysis of observational data regarding the urban boundary layer, it has been proposed that gusty wind is coherent and plays an important role in the transport of both sand and dust. Based on sand-laden flow data from the QLOA, Gu, Wang, Zhu, and Zheng (2019) compared the scales of VLSMs and LSMs with those of gusty wind in normalized energy spectra. They found that meteorological gusty wind contains a large number of synoptic waves but is missing the VLSMs and LSMs that have considerable contributions to the turbulent kinetic energy.…”

Experimental investigation of the effects of the turbulence on the impact force of flash flood

“…We will analyse whether the impact force is directly correlated with the coherent turbulent structure. To clarify that the time scales and energy fractions between the streamwise velocity and the impart force, we obtained their normalized energy spectra using the wavelet transform method (Baas, 2006;Tang et al, 2013;Zheng et al, 2013;Gu et al, 2019). We used the basis functions of the Daubechies wavelet in this study.…”

“…Moreover, an important focus of research on turbulence was inspired by the observation of coherent structures in turbulent boundary layers (Theodorsen, 1952;Kline et al, 1967;Townsend, 1976). Smits et al (2011) identify four principal characteristic elements of turbulent structure: near-wall streaks, hairpin or horseshoe vortices, large-scale motions (LSMs) and very-largescale motions (LSMs) (Theodorsen 1952;Kline et al, 1967;Kim and Adrian 1999;Wang and Zheng, 2016;Gu et al, 2019;Wang et al, 2020). Notably, the coherent structures have been evidenced in wall-bounded flows and demonstrated to play a crucial role in the turbulent kinetic energy (TKE), the momentum flux and the mass transport process (Baas and Sherman, 2005;Balakumar and Adrian, 2007;Dupont et al, 2013;Zheng et al, 2013;Wang et al, 2017).…”

Modelling the nacelle wake of a horizontal-axis wind turbine under different yaw conditions

“…The wake structure is considered as one of the most important wind turbine aerodynamics characteristics [1]. Recently, with the ever rapid growing speed of wind turbine scale, the flow around a utility wind turbine can reach high Reynolds numbers of Re ∼ O(10 6 ) [2,3,4], resulting in prohibitively large computational resources required for a high-fidelity large-eddy simulation (LES) based on body-fitted grid. To address the physics cost-effectively, researchers and technology developers determined that a hybrid approach combing high fidelity and efficiency must be developed such as actuator disk model (ADM) [5,6], actuator line model (ALM) [7,8], actuator surface model (ASM) [9], and some reduced-order methods [10,11,12].…”