“…To avoid the above two limitations in the conventional methods, the machine learning method is useful. In recent years, machine learning has been used to study many problems in fluid mechanics, including turbulence modelling (Ling & Templeton 2015;Ma, Lu & Tryggvason 2015;Ling, Kurzawski & Templeton 2016b;Parish & Duraisamy 2016;Xiao et al 2016;Gamahara & Hattori 2017;Vollant, Balarac & Corre 2017;Wang, Wu & Xiao 2017;Wang et al 2018;Wu, Xiao & Paterson 2018;Duraisamy, Iaccarino & Xiao 2019;Wu et al 2019a;Zhou et al 2019), flow field reconstruction and prediction (Maulik & San 2017;Maulik et al 2018;Fukami, Fukagata & Taira 2019;Huang, Liu & Cai 2019;Lee & You 2019) and, more relevant to the present study, flow field identification (Colvert, Alsalman & Kanso 2018;Alsalman, Colvert & Kanso 2019;Wu et al 2019b). To solve the identification problems, there are two main machine learning approaches, namely, classification and clustering.…”