نتایج جستجو برای: constriction scour
تعداد نتایج: 17116 فیلتر نتایج به سال:
The most important cause of concern about the stability of bridge foundation is the occurrence of scour around bridge piers. Therefore, different methods have been proposed to prevent or reduce scouring around bridge piers. The use of groynes is one of the modern methods to control and reduce local scour. In the present study, the effect of a solid groyne on reduction of the scour depth around ...
In this paper, the local scour process around pipelines due to steady currents has been investigated from different points of view using the numerical and physical models. In order to calculate the maximum scour depth under the pipe, a mathematical model based on the two-dimensional Laplace equation has been developed and the scour process on the 2D x-z vertical plane has been simulated, with t...
This paper presents, a set of experiments was conducted in a Plexiglas flume setup to investigate the simultaneous use of pipe and blade in the scour control around a submerged pipe. A vertical cylindrical pipe with and without a blade placed below it was selected for the experiments. The experiments were carried out in two different sates: with blade and without blade the pipe. Moreover, they ...
Nowadays, the power industry with fixed offshore wind turbines through the renewable energies is one of the progressing industries. The installation of scour protection structures is done against the scouring process. The collars are one of the protective structures. In this study, distribution of the bed shear stress around the pier is investigated via the FLUENT software. The results have bee...
The use of slot through a pier is a new method proposed to control local scour at bridge piers. In this study, control of local scour at bridge pier is studied using 20 pier models under clear water conditions. The models consist of one circular pier without slot, three round-nosed piers without slot, and 16 piers with slot. Two slot lengths were chosen (yl=b and yl=2b, where y1 is the length o...
background: compressive neuropathy of median nerve is relatively common but development of an hourglass like constriction is a rare phenomenon. the purpose of this study is to show morphologic changes of median nerve in advances carpal tunnel syndrome. methods: eighty patients with thenar atrophy, anesthesia and paresthesia of first, second and third finger and severe changes of emg‑ncv were ch...
An experimental study has been conducted on the effectiveness of two types of flow-altering countermeasures placed around a cylindrical pier under clear water condition, which include sacrificial piles and submerged vanes. Their arrangements follow the optimal configurations recommended in the published articles with some modification. The temporal evolution of maximum scour depth and its equil...
The most important causes of bridge failure are local scour. In this study, laboratory experiments were conducted to investigate the effectiveness of slot as a protection device in reduction of depth of scour at cylindrical piers under clear water flow conditions. The development time of scour depth at the circular pier with and without a slot as a protection device was conducted. The experimen...
In nature, a direct route to the river is uncommon. Most rivers have channels that bend wherea complex scour pattern dominates. We have intended to study the behavior patterns necessary to scour a river known as the dominant bends. Numerical models are powerful instruments for the prediction of such areas and can provide a good understanding of these areas. In the present study we have used a t...
In this study, a new procedure to determine the optimum dimensions for a rectangular collar to minimize the temporal trend of scouring around a pier model is proposed. Unlike previous methods of predicting collar dimensions around a bridge pier, the proposed approach concerns the selection of different collar dimension sizes around a bridge scour in terms of the flume's upstream (Luc/D), downst...
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