Scale effects in physical piano key weirs models. Issue 6 (1st November 2016)

• Record Type: Journal Article
• Authors: Erpicum, Sebastien; Tullis, Blake P.; Lodomez, Maurine; Archambeau, Pierre; Dewals, Benjamin J.; Pirotton, Michel
• Is Part Of: Journal of hydraulic research. Volume 54:Issue 6(2016)
• Page Start: 692
• Page End: 698
• Publication Date: 2016-11-01
• Subjects: Physical modelling -- piano key weir -- scale effects -- surface tension -- viscous effects -- Weber number; Hydraulics -- Research -- Periodicals; Hydraulic engineering -- Periodicals; Hydraulic engineering; Electronic journals; Periodicals; 621.2
• DOI: 10.1080/00221686.2016.1211562
• Languages: English
• ISSNs: 0022-1686

Abstract

ABSTRACT: With inertia and gravity representing the dominant forces for most open channel flow applications (e.g. weir flow), Froude similitude is commonly used for scaling hydraulic performance data from the model to prototype structures. With weir flow, as the upstream head decreases, however, the relevance of surface tension and viscosity forces can increase to the point when the model and prototype similitude is not fully achieved through Froude scaling. Such discrepancies are referred as size-scale effects, and among other things, can result in variations in the head–discharge relationship, nappe trajectory, and air entrainment. Published criteria for avoiding significant size-scale effects for free flow over linear weirs have suggested that minimal heads of ∼0.02 to 0.07 m be respected, independently of the model size. In this study, the size-scale effect, minimum upstream head, and Weber number limits are investigated for four piano key weirs with geometric model scales of 1:1, 1:7, 1:15, and 1:25.