مهندسی دریا
Vida Atashi; Mehdi GHomeshi
Abstract
In this paper, the effect of in phase or out of phase fluctuation of two tandem circular cylinders with PTC on FIM is investigated. Flow-Induced Motion (FIM) is a phenomenon that frequently occurs when slender structures are subjected to a transverse fluid flow.VIV and galloping are the most common phenomena ...
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In this paper, the effect of in phase or out of phase fluctuation of two tandem circular cylinders with PTC on FIM is investigated. Flow-Induced Motion (FIM) is a phenomenon that frequently occurs when slender structures are subjected to a transverse fluid flow.VIV and galloping are the most common phenomena in FIM which occurs due to interaction between shear layers and wakes of upstream cylinders. In this paper, the effect of tandem spacing on FIM of two circular cylinders with PTC is investigated by visualization. The power harness graphs for upstream, downstream and synergy was extracted with VIVACE. The VIVACE consists of a rigid bluff body that is mounted on an elastic base and exposed to fluid flow. The mechanical energy from the cylinder vibration is also transmitted by a PTO to a generator. Normally, the harness power in galloping region increases with increasing in flow velocity and Reynolds number. Unlike what was expected, drops and jumps in Power harness in the velocity range of 0.9
مهندسی دریا
Parisa Koochak; Seyed Mahmood Kashefipour; Mehdi Ghomeshi; Ahmad Fathi
Abstract
One of the ways to control the erosion in the outer bend of rivers is to use spur dikes. In recent years, the efficiency, affordability and environmental suitability of traditional spur dikes has been criticized. Therefore the importance of adopting methods which are both cost-effective and eco-friendly ...
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One of the ways to control the erosion in the outer bend of rivers is to use spur dikes. In recent years, the efficiency, affordability and environmental suitability of traditional spur dikes has been criticized. Therefore the importance of adopting methods which are both cost-effective and eco-friendly has been addressed. The bandal-like spur dike is a combination of a permeable and an impermeable spur dike, which is usually used in Indian Sub-Continents for riverbank protection and improvement of navigation conditions in alluvial rivers. It is made of bamboo therefore it is inexpensive and environmental friendly. In this research the effect of the permeability percentage of the bandal-like structure on the maximum scour depth around it in a 90 degree mild bend flume and in submerged condition is investigated. Therefore a series of impermeable spur dikes (0% permeability) and bandal-like structures with (33,50 and 64) percent permeability are placed in the flume and examined under four different Froude numbers (0.21, 0.23, 0.26, 0.29). The results showed that the maximum scour depth around the bandal-like structure is considerably less than the maximum scour depth around impermeable spur dikes. Also by increasing the permeability percentage of the bandal-like structures the maximum scour depth around it decreases.
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.