جستجوی مقالات مرتبط با کلیدواژه "submerged condition" در نشریات گروه "آب و خاک"

In the sediment washing method under submersible flow, the volume of the discharged sediments depends on various parameters, which can be referred to the depth of the water inside the tank, the depth of the water inside the pond, the output flow from the lower discharger, the size and type of accumulated sediments inside the tank. did To check the mentioned parameters in this research, a physical model with a length of 1 meter, a width of 1 meter and a height of 1.10 meters and by performing various tests using 2 water heights inside the tank, 3 water heights inside the pond and with 3 types of sediment granulation (in total 18 experiments) were investigated and studied. The results of this research show that in sediment washing under pressure, when the lower discharger returns for sediment washing, a sediment washing cone is formed in front of it. The dimensions of the formed sediment washing cone depend on the discharge from the lower discharger, the height of the water inside the tank and the diameter of the sediments accumulated inside the tank, so that the measurement results show that in order to keep the height of submerged water constant, the height of water inside the tank increases. It increases the volume and length of the sediment washing cone. Also, for a fixed water height inside the tank, increasing the submerged water height increases the volume and length of the sediment washing cone.

The purpose of this study is to compare the scouring hole geometric dimensions for three kinds of spur-dike: permeable, impermeable and bandal-like for submerged conditions by conducting a set of experimental tests. Bandal-like is made by combining permeable and impermeable spur-dikes.Experimental tests were carried out in a straight flume at a constant structure height equal to 12cm and three angels equal to 60, 90, 120 degrees at a constant flow condition (Fr=0.24 , y=16cm). Results were presented as bed topography, depth, length and width of scour hole. It was found that the ratio of maximum scour to flow depth occurs at 90, 120, 120 degrees for impermeable, permeable and bandal-like spur dike, respectively. Permeable part of bandal-like was found to be effective in decreasing the ratio of maximum scour depth to flow depth and the ratio of scour width to flow depth. The ratio of maximum and minimum scour width to flow depth occurs at 60 and 90 degrees, respectively for three kinds of spur-dikes. The ratio of maximum scour length to flow depth in impermeable, permeable and bandal-like occurs at 90, 60 and 60 degrees, respectively. Impermeable part of bandal-like was found to be effective in increasing the ratio of maximum scour length to flow depth.

Stochastic weather generators are used in a wide range of studies, such as hydrological, environmental applications and agricultural risk assessments and can produce time series of synthetic daily weather data of proper duration. In the present study, the performance of the LARS-WG model was analyzed in four northern and eight southern coastal stations of Iran, in relation to the simulation of wet/dry series, precipitation, temperature, solar radiation and the simulation of temperature extreme events. The results showed that the model performance was very acceptable in relation to daily distribution, monthly, and seasonal mean of almost every series. However, its performance in estimating the values of total monthly precipitation standard deviation, mean monthly temperature standard deviation and mean monthly solar radiation standard deviation was not tolerable. In the whole, the LARS-WG model had a better performance in northern stations in comparison with southern stations.