On the scaling of large-scale structures in smooth-bed turbulent open-channel flows

Contributions of different scales of turbulent motions to the mean wall-shear stress in open channel flows at low-to-moderate Reynolds numbers

“…2020 a ; Peruzzi et al. 2020, to name a few), respectively. The presence of double peaks in is easy to understand since (with ) is actually a weighted and premultiplied cospectra where dominant modes of LSMs and VLSMs are present.…”

“…As the Reynolds number increases, another dominant contribution mode at λ x = O(10h) becomes increasingly apparent. By checking the wavelength of the two peaks, it can be readily known that they correspond to the well-documented large-scale motions (LSMs) and very-large-scale motions (VLSMs) (Kim & Adrian 1999;Guala, Hommema & Adrian 2006;Balakumar & Adrian 2007;Monty et al 2009;Cameron, Nikora & Stewart 2017;Duan et al 2020a;Peruzzi et al 2020, to name a few), respectively. The presence of double peaks in k…”

On the influence of collinear surface waves on turbulence in smooth-bed open-channel flows

“…The experiments were carried out in the same flume facility and with the same set-up and instrumentation as those described by Peruzzi et al. (2020). For this reason, in the text that follows we provide only a brief description of the equipment; for further details we encourage the reader to refer to the paper by Peruzzi et al.…”

“…The aspect ratio is also known to significantly affect the scaling of energetic large eddies populating CA flows (often referred to as very-large scale motions, VLSMs, see Peruzzi et al. 2020; Zampiron, Cameron & Nikora 2020). In an attempt to shed light on the size and scaling of dominant eddies emerging from the interaction between waves and currents, this is an issue that should be taken into account when interpreting experimental data but, so far, it has been ignored probably because the interlinks between VLSMs and aspect ratio in open-channel flows have been identified only very recently.…”

Evaluating longitudinal dispersion of scalars in rural channels of agro-urban environments

“…However, field and laboratory experiments in openchannel flows [1,59,60] reveal that spanwise heterogeneities in the riverbed trigger the formation of secondary currents also within the flow cross-section. The occurrence of secondary currents also modifies the size of the large-scale turbulent coherent structures [9,66,101] that are responsible for the transport of a large portion of the turbulent kinetic energy and momentum [54]. In light of these considerations, we can assume that the Roggia Delfinona and the Derivatore Vittuone probably behave as narrow open-channels, while the Roggia Gamberina as a wide open-channel.…”