Abstract
Abstract
Highlights
With the significant advances in experimental techniques and high-performance computation in recent years, there has been overwhelming evidence indicating the existence of large-scale structures away from the wall in wall turbulence (see, for example, Smits, McKeon & Marusic (2011), and the references therein), and it has been observed that influences from the large-scale outer structure affect the magnitude of small-scale events in the near-wall region (e.g. Hutchins & Marusic 2007; Dogan et al 2019)
Turbulent plane Couette flow is well known to involve a very-large-scale structure in the channel-core region which fills the entire channel gap and has an extremely large streamwise extent (e.g. Lee & Kim 1991; Bech et al 1995; Tillmark 1995; Papavassiliou & Hanratty 1997; Kitoh, Nakabayashi & Nishimura 2005; Tsukahara, Kawamura & Shingai 2006; Tsukahara, Iwamoto & Kawamura 2007; Kitoh & Umeki 2008; Tsukahara, Tillmark & Alfredsson 2010; Pirozzoli, Bernardini & Orlandi 2014; Avsarkisov et al 2015; Kawata & Alfredsson 2016; Lee & Moser 2018). The uniqueness of this flow is that the very-large-scale structure appears at moderate Reynolds numbers due to the non-zero turbulent energy production at the channel centre, and clear scale separation between this outer structure and the smaller-scale structure near the wall can be achieved at relatively low Reynolds numbers compared to other wall turbulence configurations, such as turbulent channels, pipes and boundary layers
We perform a series of DNS of turbulent plane Couette flow where either the streamwise or the spanwise domain length is systematically reduced to be as small as the minimal length, and we investigate how scale interactions in this flow are affected by such domain-size reductions
Summary
With the significant advances in experimental techniques and high-performance computation in recent years, there has been overwhelming evidence indicating the existence of large-scale structures away from the wall in wall turbulence (see, for example, Smits, McKeon & Marusic (2011), and the references therein), and it has been observed that influences from the large-scale outer structure affect the magnitude of small-scale events in the near-wall region (e.g. Hutchins & Marusic 2007; Dogan et al 2019). Lee & Kim 1991; Bech et al 1995; Tillmark 1995; Papavassiliou & Hanratty 1997; Kitoh, Nakabayashi & Nishimura 2005; Tsukahara, Kawamura & Shingai 2006; Tsukahara, Iwamoto & Kawamura 2007; Kitoh & Umeki 2008; Tsukahara, Tillmark & Alfredsson 2010; Pirozzoli, Bernardini & Orlandi 2014; Avsarkisov et al 2015; Kawata & Alfredsson 2016; Lee & Moser 2018) The uniqueness of this flow is that the very-large-scale structure appears at moderate Reynolds numbers due to the non-zero turbulent energy production at the channel centre, and clear scale separation between this outer structure and the smaller-scale structure near the wall can be achieved at relatively low Reynolds numbers compared to other wall turbulence configurations, such as turbulent channels, pipes and boundary layers. Our focus is placed on how the turbulence transport by scale interactions is affected by the disappearance of the very-large-scale structure; we aim to elucidate the role of the interactions between the inner and outer structures in the turbulence interscale transport
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