آبگیرهای کفی از جمله سازه‌هایی هستند که معمولا" در مناطق کوهستانی ساخته می‌شوند. در بحث آبگیری از رودخانه‌ها،روش‌های متعددی وجود دارد که هر یک ویژگی‌ها و محدودیت‌های خاص خود را دارند. آبگیری از جریان آب در رودخانه‌ها معمولا به دو روش پمپاژ و ثقلی صورت می‌گیرد. روش ثقلی More
آبگیرهای کفی از جمله سازه‌هایی هستند که معمولا" در مناطق کوهستانی ساخته می‌شوند. در بحث آبگیری از رودخانه‌ها،روش‌های متعددی وجود دارد که هر یک ویژگی‌ها و محدودیت‌های خاص خود را دارند. آبگیری از جریان آب در رودخانه‌ها معمولا به دو روش پمپاژ و ثقلی صورت می‌گیرد. روش ثقلی به دلیل پیوسته بودن و عدم نیاز به صرف انرژی بر روش پمپاژ ارجحیت دارد. روش‌های مختلفی به طریق ثقلی امکان پذیر می‌باشد که معمولا به سه دسته آبگیرهای جانبی، جلویی و کفی تقسیم بندی می‌شوند. با توجه به تجربیات بدست آمده در کشور‌های اروپایی برای مناطق کوهستانی و کوهپایه ای با شیب طولی رودخانه بیش از یک درصد در حالی که 75 درصد بار بستر دارای ابعاد بزرگتر از 6 میلی متر باشد، آبگیر کفی توصیه گردیده است. با توجه به اینکه تحلیل هیدرولیکی جریان در آبگیر کفی چندان توسط مدل‌های ریاضی مورد بحث قرار نگرفته و از طرفی بررسی و ساخت مدل‌های فیزیکی زمان بر و پر هزینه است ، بنابراین در این پژوهش، شبیه سازی هیدرولیک جریان در آبگیر کفی، توسط نرم افزار Flow3Dمورد نظر قرار گرفت.در این پژوهش مشاهده گردید که بهترین شیب شبکه آبگیر، برای آبگیری شیب 20 درجه می‌باشد. از طرفی هر قدر درصد بازشدگی شبکه آبگیر افزایش یابد، نسبت دبی انحرافی نیز افزایش می‌یابد. همچنین تغییرات ضریب شدت جریان در حالت‌های مختلف نسبت به عدد فرود ، شیب و درصد بازشدگی بررسی شد که با توجه به نمودارهای بدست آمده مشخص شد که افزایش عدد فرود و درصد بازشدگی شبکه آبگیر، باعث کاهش ضریب تخلیه جریان می‌گردد.
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Due to the importance of stilling basin blocks and the significant effect of their shape and dimension on energy dissipation, and since various studies have been carried out on hydraulic jump properties and properties of stilling basins while fewer studies have addresse More
Due to the importance of stilling basin blocks and the significant effect of their shape and dimension on energy dissipation, and since various studies have been carried out on hydraulic jump properties and properties of stilling basins while fewer studies have addressed the effect of integrated sinusoidal blocks on hydraulic jump properties, the present research was designed to analyze the effect of sinusoidal blocks height using the Flow 3D model, which is a powerful software product for simulating flow turbulence in two or three dimensions. Froude numbers in this research ranged from 4.6 to 12.2, which indicated that as flow’s Froude number increases from 4.2 to 11, the length of roller and hydraulic jump escalate. Moreover, relative roller length changes for about 30% to 40% by changing the height of blocks. Consequently, jump submerges in the beginning of outflow of flow from below the vent and output flow dissipates quickly. Jump length also decreases with an increase in blocks height. Finally, roller length decreases by 40 to 50 cm with outflow of flow from below the vent for the following two values: (The wave steepness) t/s=0.25 and 0.75.
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Abstract In this study, the effect of two full-float crowns on reducing scouring around the axial axially was evaluated numerically using flow 3d software and the results were compared with the same laboratory study and a useful application graphic was extracted in this More
Abstract In this study, the effect of two full-float crowns on reducing scouring around the axial axially was evaluated numerically using flow 3d software and the results were compared with the same laboratory study and a useful application graphic was extracted in this field. It was determined that the dimensions of the crown have a significant effect on its performance. The results showed that with increasing crown dimensions its performance improves.by comparing two types of crowns, it was found that if the crown reaches along the length of more than half the support length, the crowns of the el form more effective than the full crown. The crowns are better off because they do not prevent the movement of sediments from the rising vortex activity at the bottom of the arm; on the other hand, the crowns of the shape due to the smaller area than the crowns, if applicable, are applied. Economically, they will be more economical
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In this research, in order to optimize the marine structures through changing their shape and distances, the force in each of the base group columns was investigated. In the present thesis, the shape of spindle was used for the cross section of the columns because the s More
In this research, in order to optimize the marine structures through changing their shape and distances, the force in each of the base group columns was investigated. In the present thesis, the shape of spindle was used for the cross section of the columns because the spindle shape has a better hydrodynamic quality when encountering waves. Moreover, the shape was investigated more closely in four vertex angles encountering waves with the 30°, 45°, 60°, and 90° angles. Afterwards, each of these spindle shapes were investigated in five different equal longitudinal and latitudinal distances with the results being presented in diagrams in the present paper. These five distances presented as dimensionless ratios S/D include 1.8, 2.9, 4, 5.5, and 9. The results indicate that the amount of force is directly proportional to the vertex angle, and inversely proportional to the columns' distance from each other.
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In this research, a numerical study on the series of straight spur in clear water conditions with a Permeability of 0, 35 and 50%. and the effect of grain size, and also hydraulic condition on scouring around them, and in order to Numerical analysis of the Effect of str More
In this research, a numerical study on the series of straight spur in clear water conditions with a Permeability of 0, 35 and 50%. and the effect of grain size, and also hydraulic condition on scouring around them, and in order to Numerical analysis of the Effect of straight spur Permeability on current Pattern and Scouring Using Model flow 3 d the results show that in fixed distance between spures, with flow increases, the scour depth increases.. In constant flow, by increasing distance between spures, the amount of relative scour depth is decreasing and the most of depth of scour occurs in vicinity of first spure. Also, in fixed grain size, by increasing the froude number, also the amount of relative scour depth is increasing.
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