مطالعه توزیع فشار غیر هیدرواستاتیک جریان با سطح آزاد در یک محیط متخلخل سنگریزه‌ای

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشجوی دکتری سازه‌های آبی، گروه مهندسی آبیاری و آبادانی، پردیس کشاورزی و منابع طبیعی، دانشگاه تهران

2 استاد گروه مهندسی آبیاری و آبادانی، پردیس کشاورزی و منابع طبیعی، دانشگاه تهران

3 دانشیار گروه علوم خاک، دانشکده کشاورزی، دانشگاه یاسوج

چکیده

با افزایش شیب سطح آب و بستر و یا ایجاد انحنای قابل ملاحظه در خطوط جریان، توزیع فشار عمودی از حالت هیدرواستاتیک خارج می‌شود. در محیط‌های متخلخل سنگریزه‌ای به دلیل افت شدید انرژی و اختلاف زیاد بین تراز آب بالادست و پایین‌دست محیط، توزیع فشار از نوع غیر هیدرواستاتیک مورد انتظار است. در این مقاله با استفاده از تئوری پای باکینگهام و تحلیل رگرسیون، رابطه‌ای برای نیمرخ طولی سطح آب در محیط‌های متخلخل سنگریزه‌ای ارائه شده و همچنین با استفاده از معادله اولر و با در نظر گرفتن اثرات شیب زیاد و انحنای عمودی خطوط جریان، رابطه توزیع فشار غیر هیدرواستاتیک در محیط‌های متخلخل سنگریزه‌ای به دست آمده است. نتایج آزمایشگاهی نیمرخ طولی سطح آب و نیمرخ طولی فشار وارد بر کف در محیط متخلخل سنگریزه‌ای با قطر متوسط ذرات 68/1 سانتی‌متر و دو طول 5/0 و 0/1 متری تطابق خوبی با روابط ارائه شده نشان می‌دهند به طوری که متوسط قدر مطلق خطای نسبی مقادیر محاسباتی این دو نیمرخ به ترتیب برابر با 31/1 و 71/1 درصد است.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Study of non-hydrostatic pressure distribution of free surface flow in a rockfill porous media

نویسندگان [English]

  • Amir Gord-Noshahri 1
  • Ebrahim Amiri Tokaldany 2
  • Mohammad Sedghi-Asl 3
1 PhD Candidate of hydraulic structures, Dept. of Irrigataion and Reclamation Engineering, Faculty of Agriculture and Engineering Technology, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
2 Full Professor, Dept. of Irrigataion and Reclamation Engineering, Faculty of Agriculture and Engineering Technology, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran
3 Assistant Professor, Dept. of Soil Science, College of Agriculture, Yasouj University, Yasouj, Iran
چکیده [English]

Increasing the slopes of water surface and bed or making a considerable curvature of streamlines, resulted in the vertical pressure distribution deviate from hydrostatic distribution. Because of severe energy loss and big difference between upstream and downstream water surface elevations in rockfill porous media, it is expected that pressure distribution be non-hydrostatic. In this paper, with the aid of Buckingham π theorem and regression analysis, a relationship is proposed for water surface profile in rockfill porous media. Moreover, a non-hydrostatic pressure distribution for rockfill porous media is derived by applying Euler equation including the effects of streamlines curvature and large slopes. A series of laboratory experiments have been conducted on rockfill materials with diameter of 1.68 cm and two media length of 0.5 and 1.0 m. It is found that the introduced model gives satisfactory results compare to the experimental results so that mean absolute relative error of water surface and longitudinal pressure profile between two series of the data are 1.31 and 1.71 percent, respectively.

کلیدواژه‌ها [English]

  • Coarse material
  • Euler equation
  • Longitudinal pressure profile
  • Turbulent Flow
  • Water surface profile
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