Simulating and investigating the impact of bedform geometric features on flow structure in three-dimensional dunes

نوع مقاله : Special Issue: New Approaches to Water and Soil Management and Modeling

نویسندگان

1 Former M.Sc. Student, Department of Water Sciences and Engineering, College of Agriculture, Isfahan University of Technology, Isfahan, Iran

2 Assistant Professor, Department of Water Sciences and Engineering. College of Agriculture, Isfahan University of Technology, Isfahan, Iran

چکیده

The river bed forms are noteworthy investigated from the hydraulic and environmental point of view. For many years, river engineers have researched the flow structure in the presence of sandy river bedforms. Due to the limitations in laboratory and field studies, numerical methods can accurately examine the flow structure of river bedforms. In this research, flow simulation on three-dimensional dunes was performed using computational fluid dynamics (CFD). Also, the effect of changes in bed form angle, bed form wavelength, and the curvature of the three-dimensional dune crest line was investigated. The results showed that in the lobe-shaped dune at the centerline channel, the maximum stream-wise velocity was 20cm/s; however, for the saddle-shaped dune, a similar value was 31cm/s. Also, the separation zone is 7cm and 30cm for the lobe- and saddle-shaped bedforms, respectively. Also, increasing the lee-side angle from 15 to 30 degrees caused the 20% velocity reduction at the dune crest, for the lobe- and saddle-shaped bedform; however, 50% and 10% reduction in the stream-wise velocity was illustrated at the lee-side, for the lobe- and saddle-shaped bedform, respectively. Meanwhile, for the saddle-shaped bedform, the velocity increased and the Reynolds shear stress decreased with the decrease of the exit angle. Increasing the wavelength from 25 to 96 cm showed the 20% stream-wise velocity reduction at the dune crest, for the lobe- and saddle-shaped bedform; however, 40% and 10% reduction in the stream-wise velocity was illustrated at the lee-side, for the lobe- and saddle-shaped bedform, respectively. Decreasing the curvature crest line showed a 15% reduction and 20% increase in stream-wise velocity at the dune crest, for the lobe- and saddle-shaped bedform, respectively; however, a 50% reduction and 20% increase in the stream-wise velocity was illustrated at the lee-side, for the lobe- and saddle-shaped respectively. Meanwhile, for the saddle-shaped bedform, the increase in the curvature of the crest line has led to a decrease in velocity and, in most cases, an increase in Reynolds shear stress.

کلیدواژه‌ها

موضوعات

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مدل سازی و مدیریت آب و خاک
دوره 6، Special Issue
Guest Editor: Dr. Raoof Mostafazadeh
خرداد 1405
صفحه 67-88

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  • تاریخ دریافت: 24 مهر 1404
  • تاریخ بازنگری: 16 آبان 1404
  • تاریخ پذیرش: 16 آبان 1404

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