مهندسی دریا
hossein bahrami; Mehdi Ghomshi; Seyed Mahmoud kashefi por; Seyed Ali Akbar Salehi Neyshabouri
Abstract
It is well known that the shortage of water is one of the most serious problems that faces the mankind. Therefore the study and search for the phenomenon that have impact on the water reservoirs and other natural resources of water, is essential. One of the most fundamental phenomenons relating to water ...
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It is well known that the shortage of water is one of the most serious problems that faces the mankind. Therefore the study and search for the phenomenon that have impact on the water reservoirs and other natural resources of water, is essential. One of the most fundamental phenomenons relating to water reservoirs is the density currents. The importance of the investigation and analysis of the hydraulic behavior of density currents will be apparent when we consider the consequences of the occurrence of these currents and its effects on the erosion of water reservoirs and also the sediments that they cause to be deposited in these reservoirs. For example the incoming of these currents in water reservoirs will effect the biological activities, it may cause sediments in these water reservoirs or it might press down these sediments to the bottom of water reservoirs.
مهندسی دریا
hossein bahrami; Mehdi ghomeshi; Seyed Mahmoud kashefi por; Seyed Ali Akbar Salehi Neyshabouri
Abstract
Density current is one of the relative motions that occur between two fluid layers, even in fluids with small difference in density. Differences in specific mass may cause of temperature, suspended material, solved material or a combination of them. These currents are so important specially in cases ...
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Density current is one of the relative motions that occur between two fluid layers, even in fluids with small difference in density. Differences in specific mass may cause of temperature, suspended material, solved material or a combination of them. These currents are so important specially in cases such as water containing sediment entering rivers into dam reservoir, seas or lakes and can also have destructive effects such as sedimentation in reservoir and estuaries to the sea and coastal areas as well as changing bedding sets Offshore areas (Kostic & Parker, 2005). The identification of type of move and change in current regime on the characteristics of the flow movement is very important. Investigation of flow movement, require to recognition of velocity profiles. A physical modeling used for this proposes and measurement and investigation of velocity on the body of current carried out. The results showed that the Coefficients of velocity profiles in wall and jet regions were respectively 2.83, 0.87 and 2.08 for sub critical flow and 1.174, 1.062 and 2.09 for super critical flow, also the maximum height of the supercritical flow was lower than sub critical flows. The other results showed that the velocity reduced 14 to 19 percent and the flow depth increased 21 to 32 percent affected by hydraulic jump respectively. Also, in some cases, large differences were observed between the results of the analytical jump relationship and measured data.
مهندسی دریا
Morteza Bakhtiari; seyed mahmood kashefipour; Mehdi GHomeshi
Abstract
One application of spur dikes is ensure navigability of rivers Through regulation and stabilization of sufficient width and depth, balance changes for the development of depth and The radius of curvature.Nowadays, spurs are also employed for promoting environmental conditions along a riverbank. One of ...
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One application of spur dikes is ensure navigability of rivers Through regulation and stabilization of sufficient width and depth, balance changes for the development of depth and The radius of curvature.Nowadays, spurs are also employed for promoting environmental conditions along a riverbank. One of the important topics abut spurs is their protection against scouring that has been less studied. One of the simple and economic ways for protection of spur against scouring is using riprap. Riprap is very common because it is easily available, cheap and simple for construction.Since using, spur dikes to protect riverbanks spatially in bends is very common, This research was carried out in order to investigate the effect of the structure stability. The purpose of this study is evaluation of depth-placed riprap for protection of spur dike in 90° Bend. In order to achieve the research objectives, one riprap size of inch diameter was used. Ripraps are placed in 3 depths ( ), and used for 3 lengths of spur(15%,20% and 25% width of flume), two angles (90 and 120 degree) and three longitude distance (3,5 and 7 times of spur length). Parameters as variables in this study were selected which The results can be used in large rivers, including navigable rivers and the Gulf.The results showed that stability of ripraps are increased with increasing the depth-placed riprap and angle of spurs, whereas increasing in spur length and longitude distance decreases stability of ripraps.
seyed Mahmood Kashefipour; Mehdi GHomeshi
Abstract
scouring and sedimentation is one of the most important topics in costal that always has been consider for river, coastal and marine structure engineers. Using RipRap is one of the simplest and economical methods for coastal protection that is very common because it is easily available, cheap and simple ...
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scouring and sedimentation is one of the most important topics in costal that always has been consider for river, coastal and marine structure engineers. Using RipRap is one of the simplest and economical methods for coastal protection that is very common because it is easily available, cheap and simple for construction and low costs. Rip Rap directly and indirectly used for protection of coastal against of erosion.one of the most important topics about is provide a criteria for its design and selection that has been less studied and available investigations are in straight route while due to flow pattern in the bends scouring is sever. The purpose of this study is provide a RipRap design criteria for protection of coastal against scouring. In order to achieve the research objectives, in the laboratory conditions evaluated one riprap size of inch diameter, lengths , distances and angels. The results showed equations for design of riprap and in another part of this study evaluate present equation of other researchers for using in the bends.