Author(s): Juan P. Toro; G. Coronado

Linked Author(s):

Keywords: Stepped spillway; non-aerated flow region; instantaneous pressure; fluctuating pressure

Abstract: A numerical study of instantaneous pressures at points of interest in the non-aerated region of a steep stepped spillway was performed, for which very recent experimental measurements exist from a physical model. The objective is to compare the experimental fluctuating pressures measured on the horizontal step treads with a computational model capable of collecting instantaneous flow pressure data. The chosen hydraulic model is a stepped spillway with 60 steps, with a slope of 0.75H:1V (53.13°). The employed unit discharge was 0.5 m2/s (q), which corresponds to a dimensionless critical depth (yc/h) of 4.9 and a Reynolds number of approximately 5x105. Under these conditions, the observed air entrainment point in the experiments was located approximately at step 31. The implemented numerical model includes a portion of the same geometry as the experimental model. Comparison of experimental and computed values of mean, instantaneous and fluctuating pressures was undertaken in the non-aerated region, between steps 5 to 30, at 8 mm from the solid edges of the steps, following the same methodology as the experimental study. Overall, the numerical model reproduces the trends in mean values of these variables quite well; however, it overestimates turbulent fluctuations. This causes more extreme negative pressures than those reported in experiments and lower positive peak pressures. Our numerical implementation constitutes a first step towards implementing tools to predict instantaneous pressures in the non-aerated region of steep stepped spillways.

DOI: https://doi.org/10.3929/ethz-b-000675921

Year: 2024