Comments about Davey et al. [1] A two-experiment approach to hydraulic jump scaling

These Comments address the paper by K. Davey, A. Al-Tarmoom, H. Sadeghi, A two-experiment approach to hydraulic jump scaling, Eur. J. Mech. B Fluids, 111(3) (2025) 215–228 [1], from the perspective of practical hydraulics. The modelling and scaling of complex fluid flows at reduced size, including hydraulic jumps, are explained in more detail. Particular attention is given to the Froude scaling laws, which correspond to some of the scaling relations derived in Ref. [1]. The discussion then extends to alternative theoretical and empirical approaches to address scale effects in hydraulics, in addition to the finite similitude scaling theory [1]. These include precise Froude scaling, one-parameter Lie group point-scaling transformations, Reynolds number invariance, numerical quantification of scale effects and the scale series method. Finally, possible future research paths, building upon the work in Ref. [1], are outlined. • These Comments address the paper by Davey et al. [1] • Scaling of complex fluid flows at reduced size is explained in more detail • This includes the Froude scaling laws, related to the scaling relations of Ref. [1] • Five alternative approaches for addressing scale effects in hydraulics are covered • Possible future research paths, building upon Ref. [1] , are outlined