Unsteady turbulence, dynamic similarity and scale effects in bores and positive surges

作者：Leng Xinqian; Chanson Hubert^*

来源：European Journal of Mechanics - B: Fluids , 2017, 61: 125-134.

DOI：10.1016/j.euromechflu.2016.09.017

• Unsteady turbulence
• Dynamic similarity
• Scale effects
• Bores and surges
• Free-surface flow properties
• Froude similitude

A tidal bore is a positive surge or compression wave formed in an estuarine system during the early flood tide under macro-tidal conditions. A series of physical experiments were conducted in a large facility to investigate the unsteady free-surface properties, velocity characteristics and Reynolds shear stresses. Both instantaneous and ensemble-averaged measurements were performed. The results demonstrated the intense turbulence and turbulent mixing under breaking and undular tidal bores. A range of dimensionless unsteady turbulent properties were carefully compared based upon both Froude and Morton similitudes with two different Reynolds number ranges. The data showed that several parameters were affected by scale effects, including velocity and Reynolds stress fluctuations during the bore propagation. The finding implies that laboratory study data might not be up-scaled to prototype conditions without some form of scale effects.

• 出版日期2017-2