1. Digital appendix. video movies of air bubble motion inside the gabions
The gabion stepped configuration was characterised by the entrainment and motion of air bubbles inside the gabions. For all porous configurations, air bubbles were seen flowing through the gravel material. A series of video movies were taken with a digital camera Pentax$^{\rm TM}$ K-7 during some basic experiments. The list of movies is detailed in Table 3.
Table 3 - Video movies of air bubble motion inside the gabion stepped weir
Filename / Format / DescriptionIMGP4537.avi / HD movie (1280×720 pixels, 30 fps) / Gabion stepped spillway (q = 26.6°, h = 0.1 m), Transition flow regime (dc/h = 0.85), step cavity 7-8
Some red wool strings were attached to the wire mesh to visualise the cavity flow patterns.
IMGP4566.avi / HD movie (1280×720 pixels, 30 fps) / Gabion stepped spillway (q = 26.6°, h = 0.1 m), Skimming flow regime (dc/h = 1.5), step cavity 7-8
Some red wool strings were attached to the wire mesh to visualise the cavity flow patterns.
IMGP4633.avi / HD movie (1280×720 pixels, 30 fps) / Gabion stepped spillway (q = 26.6°, h = 0.1 m), Nappe flow regime (dc/h = 0.5), step cavity 6-7
Note the aerated cavity and bubbly motion inside the gabion gravels.
IMGP5001.avi / HD movie (1280×720 pixels, 30 fps) / Capped gabion stepped spillway (q = 26.6°, h = 0.1 m), Skimming flow regime (dc/h = 1.3), step cavities 7-8 & 8-9
IMGP5407.avi / HD movie (1280×720 pixels, 30 fps) / Capped gabion stepped spillway (q = 26.6°, h = 0.1 m), Nappe flow regime (dc/h = 0.5), step cavity 5-6
Note the aerated cavity and the free-surface line in the gabions.