بررسی عددی تأثیر شکل مقطع کانال اصلی بر دینامیک جریان در تلاقی رودخانه‌ها

نوع مقاله : مقاله پژوهشی

نویسندگان

1 گروه مهندسی آب، دانشکده کشاورزی ، دانشگاه ارومیه، ارومیه، ایران.

2 گروه مهندسی آب، دانشکده کشاورزی، دانشگاه ارومیه، ارومیه، ایران

3 گروه مهندسی آب، دانشکده کشاورزی ، دانشگاه ارومیه، ارومیه، ایران

10.22059/ijswr.2021.318648.668889

چکیده

مطالعه و شناخت دینامیک جریان در محل و پایین‌دست تلاقی، از موارد ضروری در  طراحی هندسه پایدار کانال­های منشوری و ارائه راهکار مناسب حفاظتی برای سیستم‌های‌ رودخانه­ای به حساب می‌آید. به استناد داده‌های میدانی، وجود زوایای مختلف تلاقی و اختلاف رقوم کف کانال اصلی و شاخه فرعی از رایج‌ترین مشخصات فیزیکی اغلب تلاقی­های طبیعی می‌باشد. تحقیق حاضر با هدف بررسی عددی تاثیر شکل مقطع کانال اصلی (مستطیلی و ذوزنقه‌ای) و زاویه تلاقی دو کانال (45 و 90 درجه) بر دینامیک جریان در محل تلاقی­های همکف و غیر همکف انجام گرفت. نتایج نشان داد که در تلاقی همکف با زاویه 90 درجه، ناحیه جدایی جریان در نزدیکی بستر در هر دو شکل مقطع تشکیل می­شود با این تفاوت که در مقطع ذوزنقه­ای ابعاد آن در سطح آب بیشتر از مقطع مستطیلی می­باشد. در تلاقی همکف با زاویه 45 درجه، این ناحیه در هیچکدام از مقاطع ظاهر نشد؛ اما برای تلاقی غیر همکف، ناحیه جداشدگی فقط در سطح آب و برای مقطع ذوزنقه­ای شکل گرفت. علاوه بر آن ناحیه جداشدگی جریان در تلاقی غیر همکف و تلاقی 90 درجه در نزدیک بستر شکل نگرفت اما در سطح آب، ابعاد آن در مقطع ذوزنقه­ای بیشتر از مستطیلی بود. بعلاوه، برگشت آب در بالادست تلاقی کانال اصلی، در مقطع ذوزنقه­ای و در زاویه اتصال 45 درجه کاهش یافت.

کلیدواژه‌ها


عنوان مقاله [English]

Numerical Investigation of the Effect of Main Canal Cross-Section Shape on Flow Dynamic at the Rivers’ Junction

نویسندگان [English]

  • Navid Parchami 1
  • Mohammad Hemmati 2
  • Negin MIRMORSALI 3
1 Department of Water Engineering, Faculty of Agriculture, Urmia University, Urmia, Iran.
2 Department of water engineering, Faculty of Agriculture , Urmia University, Urmia, Iran
3 Department of Water Engineering, Faculty of Agriculture, Urmia University, Urmia, Iran.
چکیده [English]

Studying and recognizing the flow dynamics at the junction and downstream of the junction is essential in designing the stable geometry of prismatic canals and providing a suitable protection solution for river systems. According to field data, the existence of different junction angles and bed discordance between the main and tributary canals is one of the most common physical characteristics of the most natural junction. The present research aims to numerically investigate the effect of main canal cross-section shapes (rectangular and trapezoidal) and junction angles (45° and 90°) on flow dynamics at river junctions of the concordance and discordance bed level. The results showed at the concordance bed level and junction with a  angle, in both cross-section shapes, the flow separation zone is formed near the bed, with the difference that in a trapezoidal section, its dimension was bigger than the rectangular section. At the  angle of the concordance bed level, this zone did not appear in any sections; but for unequal bed level junction, the separation zone was formed only on the water surface and for the trapezoidal section. In addition, the flow separation zone was not formed at the  discordance junction near the bed, but at the water surface its dimension in trapezoidal shape was more than the rectangular. Besides, the backwater at the upstream of the junction in main canal decreased in trapezoidal shape and in  junction angle.

کلیدواژه‌ها [English]

  • Open canals junction
  • Flow 3D
  • Flow pattern
  • Flow separation zone
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