مهندسی دریا
Mohammad Hosseini; Mohammad Hadi Fattahi; Saeid Eslamian
Abstract
The density current, as a part of the gravity currents, is the flow of one fluid within another caused by the density difference between two fluids. The density current consists of the nose, head, and body regions within the ambient fluid. In the present study, a flume with 8m length, 35cm width, and ...
Read More
The density current, as a part of the gravity currents, is the flow of one fluid within another caused by the density difference between two fluids. The density current consists of the nose, head, and body regions within the ambient fluid. In the present study, a flume with 8m length, 35cm width, and 40cm height was used. The experiments were performed in 28 different states by changing the bed slope, density, and discharge. The results indicated that by increasing the bed slope, the concentration of the density current decreased by 12% and 19% after continuous and local narrowing, respectively, compared to the non-narrowing state. Further, the entrainment ratio increased by narrowing the flume wall, as the Richardson number decreased by 80% and the entrainment ratio increased by 5 times after narrowing. In addition, the profile formation pattern of the current velocity and concentration enhanced by increasing the inlet density and the pattern indicated more scattering in the jet region compared to the wall region.
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 ...
Read More
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 ...
Read More
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.