Japan Geoscience Union Meeting 2016

Presentation information

Oral

Symbol H (Human Geosciences) » H-GM Geomorphology

[H-GM14] Geomorphology

Mon. May 23, 2016 10:45 AM - 12:15 PM 301B (3F)

Convener:*Hiroshi Shimazu(Department of Geography, Faculty of Geo-Environmental Science, Rissho University), Masayuki Seto(Fukushima Future Center for Regional Revitalization, Fukushima University), Chair:Hiroshi, P. Sato(College of Humanities and Sciences, Nihon University)

11:15 AM - 11:30 AM

[HGM14-09] Wind duct experiments on reptation particle motions using a high speed video camera

*Yoshinori Kodama1, Anri Takeno (1.Faculty of Regional Sciences, Tottori University)

Keywords:aeolian sediment transport mode, saltation, reptation, creep, high speed video camera, particle motion analysis

Aeolian reptating particles, splash particles by saltating grain collision to bed, were surveyed with wind duct (width: 9 cm, depth: 56 cm, lengh: 7 m28 cm), using high speed video camera (Sony, NEX-FS700R /FS700RH). 3.8 mm diameter particles of polypropylene (specific gravity: 0.9) were selected for experimental material in order to trace particle motion tracks easier. The video camera, which was set aside in the center part of the wind duct, recorded 960 frames per second. Polypropylene particles were laid at 24cm thickness. Wind condition was constant: 18 m/s. From 40 particle motion tracks, we analyzed grain speeds, accelerations and jumping heights. Most saltating particle showed more than 100 cm/s in speed and repetitions between accelerations during jumping stage and rapid decelerations after hitting the bed. While reptating particles showed less than 50 cm/s in speed and less accelerations and decelerations. Jumping heights of particles were clue to distinguish between reptation and saltation. In this experimental, if jumping height exceeds twice the grain diameter, particle shows continuous saltating motion. We had also noticed that creep mode movements, moving only by wind action, were very rare phenomena.