تخمین ضریب پخش طولی در جریان‌های سطحی با استفاده از آنالیز ابعادی

نوع مقاله : مقاله پژوهشی

نویسندگان

1 پژوهشگر وزارت نیرو

2 گروه مهندسی آبیاری و آبادانی

3 استاد/دانشگاه تهران

چکیده

ضریب پخش طولی یکی از پارامترهای مهم در حل معادله انتقال آلودگی در جریان‌های سطحی می‌باشد. در مقاله حاضر رابطه جدیدی به منظور برآورد دقیق‌تر ضریب پخش طولی در جریان آب‌های سطحی ارائه شده است. این رابطه با استفاده از داده‌های 176 رودخانه و کانال مختلف و کاربرد تکنیک آنالیز ابعادی بدست آمد. رابطة جدید ارائه شده با 18 رابطة منتخب برای مجموعة داده‌های فوق‌الذکر مورد مقایسه قرار گرفت. نتایج حاکی از دو برابر شدن دقت برآورد ضریب پخش طولی با استفاده از رابطة جدید نسبت به روابط منتخب می‌باشد. به طوری‌که این رابطه خطایی کمتر از 100± درصد را در برآورد ضریب پخش طولی از خود نشان می‌دهد. همچنین پارامترهای میانگین قدرمطلق خطا و میانگین مجذور مربعات خطا در رابطة جدید از روابط موجود کمتر و به ترتیب برابر 34/0 و 03/0 بدست آمد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Estimation of the longitudinal dispersion coefficient using the dimensional analysis in surface water flows

نویسندگان [English]

  • MEHDI MOHAMMADI GHALENI 1
  • Kumars Ebrahimi 2
  • Mohammad Hossein Omid 3
1 Researcher, Ministry of Power and Energy
2 University of Tehran
3 University of Tehran
چکیده [English]

Longitudinal dispersion coefficient is one of the most important parameters for the solution of the advection-dispersion equation. In this paper a new equation for predicting the longitudinal dispersion coefficient in surface water streams is presented. To archive this aim, a collection of 176 sets of measured field data from different canal and rivers were used, involving the dimensional analysis. Then the performance of the new equation was compared with 18 selected of well-known empirical equations, using the above mentioned data. The results show that the new equation has a twice precision in contrast to the other equations. In the other words, the calculated of the average percentage errors between the predicted and measured data for the proposed new equation was less than ±100 percent. Also, the mean absolute error and root mean square for the new equation were obtained equal to 0.34 and 0.03, respectively, which are less than other equations.

کلیدواژه‌ها [English]

  • Empirical equations
  • Estimation
  • Pollution advection
  • river
  • Surface water streams
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