بررسی اثر عمق نسبی بر مشخصات جریان در کانال مرکب پیچانرودی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی آب، دانشگاه فردوسی مشهد، مشهد- ایران

2 گروه مهندسی آب- دانشگاه فردوسی مشهد- مشهد- ایران

3 گروه علوم و مهندسی آب، دانشگاه فردوسی مشهد، مشهد، ایران

چکیده

ﯾﮑﯽ از ﺟﻨﺒﻪﻫﺎی ﻣﻬﻢ در توصیف رﻓﺘﺎر رودﺧﺎﻧﻪ، مارپیچی بودن آن ﻣﯽﺑﺎﺷﺪ. ﺗﻮﻟﯿﺪ ﺧﻢﻫﺎی ﻣﺘﻮاﻟﯽ در رودﺧﺎﻧﻪﻫﺎی ﻃﺒﯿﻌﯽ ﯾﮏ ﻣﻮﻟﻔﻪ اﺟﺘﻨﺎبﻧﺎﭘﺬﯾﺮ از ﻓﺮاﯾﻨﺪی اﺳﺖ ﮐﻪ رودﺧﺎﻧﻪ ﻃﯽ آن دچار دگرگونی ﻣﯽشود. آﮔﺎﻫﯽ از ﻫﯿﺪروﻟﯿﮏ ﺟﺮﯾﺎن در اندرکنش کانال اصلی و سیلاب‌دشت‌ به­خصوص در زمان سیلاب ﺑﺮای ﺣﻔﺎﻇﺖ خاک بستر و ﻧﯿﺰ ﺳﺎزهﻫﺎ و تاسیسات موجود ﻻزم و ﺿﺮوری اﺳﺖ. این تحقیق، برای شناخت بهتر هیدرودینامیک جریان متوسط و آشفته در کانال­های مرکب مارپیچ انجام شد. با توجه به شرایط طبیعی اکثر رودخانه­ها، به­دلیل متغیر بودن دبی و نسبت­های عمقی متفاوت (عمق جریان در سیلاب­دشت به عمق جریان در کانال اصلی)، در این پژوهش فلوم آزمایشگاهی مستطیلی پیچانرودی با سینوسیتی ثابت 3/1 برای نسبت­های عمقی متفاوت 35/0 و 55/0 بررسی شد. نتایج نشان داد که اندازه اجزاء مختلف سرعت در هر سه راستای مختصات در عمق نسبی 35/0 بیش­تر از 55/0 است که نشان از قدرت بیشتر گرداب­ها و شدت اندرکنش بین کانال اصلی و سیلاب­دشت در عمق نسبی کم­تر را داشت. همچنین با بررسی جریان­های ثانویه، وجود گرداب­های چرخشی ساعتگرد و پادساعتگرد در کانال اصلی و سیلابدشت­ها و موقیعت ایجاد این جریانات تعیین شد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Investigation of Relative Depth Effect on Flow Characteristics in Meandering Compound Channel

نویسندگان [English]

  • hamed shahsavari 1
  • Saeed Reza Khodashenas 2
  • Kazem Esmaili 3
1 Water Engineering Department, Ferdowsi University of Mashhad, Mashhad, Iran
2 Water Engineering Department, Ferdowsi University of Mashhad, Mashhad, Iran
3 Water Engineering Department, Ferdowsi University of Mashhad, , Mashhad, Iran
چکیده [English]

One of the important aspects in describing river behavior is its curvature. The production of successive bends in natural rivers is an inevitable component of the process through which the river changes. Understanding the flow behavior in the interaction between the main channel and the floodplain, especially during floods, is necessary to protect soil and water structures. This study was conducted to better understand the hydrodynamics of the middle and turbulent flow in compound meandering channels. According to the natural conditions of most rivers, due to variation of discharge and depth ratios (flow depth in floodplain to flow depth in the main channel), in this study, a rectangular meander laboratory channel with a constant sinuosity 1.3 for different depth ratios of 0.35 and 0.55 was investigated. The results showed that the size of velocity components (u,v,w) at 0.35 relative depth was greater than 0.55, which  indicating higher vortex strength and interaction intensity between the main channel and floodplain at lower relative depth. Also, by investigating the secondary flows, the existence of clockwise and counterclockwise rotational eddy currents in the main channel and floodplains and the location of these currents were determined.

کلیدواژه‌ها [English]

  • Curve Coefficient
  • Flood
  • Flow pattern
  • Meander Waterway
  • Relative Depth
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