علوم غیرزیستی دریا
mohamadreza mohamadifar; vahid chegini; MOHAMMAD ALI NAJARPOUR
Abstract
Wind waves are one of the most important environmental factors in marine engineering projects. due to the lack of measured wave data, predicted data are used to determine the climate of the waves. Today, numerical models have become the most practical tool for predicting wind waves. However, the results ...
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Wind waves are one of the most important environmental factors in marine engineering projects. due to the lack of measured wave data, predicted data are used to determine the climate of the waves. Today, numerical models have become the most practical tool for predicting wind waves. However, the results of these models are largely error-prone. Therefore, the outputs of numerical models have to be modified based on field data. A new approach used in the present study to modify the results of numerical model output variables in the computational domain is to create a local model and modify the results in boundary conditions which results in improved wave prediction in the computational domain. For this purpose, initial simulation of the waves (SWAN model) in Caspian Sea region was performed and the simulation results were compared with field data including Anzali, Noshahr and Offshore buoys. After initial simulation of the waves, the model parameter correction method is used to reduce error of the output results. By comparing the field data and the input data, we tried to approximate the results by applying the input parameter correction, which in turn improved the wave parameters and partly improved the simulation wave height. Then, a large-scale model of the entire Caspian Sea was implemented and then, a local model was defined, the boundary of which was slightly above the offshore deployment(located in the north of southern Caspian). The results show that using this method both the wave height and their periodicity are accurately predicted.
علوم غیرزیستی دریا
masoud sadrinasab; mohammad fayaz mohammadi; Vahid Chegini; amir ashtari larki
Abstract
Arvandrood is the most important shipping river at the border of Iran and Iraq at the north of the Persian Gulf. As the border is determined by the talweg of the river, the changes of the talweg, as a result of erosion and deposition, is always considering. As a reason of inertia, current of the river ...
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Arvandrood is the most important shipping river at the border of Iran and Iraq at the north of the Persian Gulf. As the border is determined by the talweg of the river, the changes of the talweg, as a result of erosion and deposition, is always considering. As a reason of inertia, current of the river tends to keep his direction forward. In meanders which the current has to change his direction, the sidewalls of the river experience severe shear stress that leads to sharp decrease of current energy and water level fluctuation, and increase of suspended sediment concentration. To simulate this in Arvandrood river, a 3D hydrodynamic model, DHI MIKE 21/3, has been employed. This model is based on a flexible mesh and the numerical solution of the two/three dimensional incompressible Reynolds averaged Navier-Stokes equations invoking the assumptions of Boussinesq and of hydrostatic pressure. In the first step, the model results were verified by the measured data in 4 stations. Comparing the water level in Faw position was shown that the Root Mean Square Error is 0.16 which is a good figure. Then, the model outputs were analyzed which show that in a straight direction of 18 kilometer from Abadan to Khosroabad, water level fluctuation and suspended sediment concentration have increased 18% and 3.8% respectively; while it is 22% and 15% in a way of 17 kilometer with two meander.
علوم غیرزیستی دریا
Parastoo Akbari; Masoud Sadrinasab; Vahid Chegini; Seyed Mostafa Siadat Mousavi
Abstract
Tide is one of the most regular changes of seas and ocean levels which are offering particular importance due to the influence on the flow pattern. According to engineering and environmental needs in industrial economic zone of Persian Gulf, Strait of Hormuz and Gulf of Oman, knowing the tidal characteristics ...
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Tide is one of the most regular changes of seas and ocean levels which are offering particular importance due to the influence on the flow pattern. According to engineering and environmental needs in industrial economic zone of Persian Gulf, Strait of Hormuz and Gulf of Oman, knowing the tidal characteristics of these areas is important. Therefore FVCOM (ocean model) was used to stimulate the tidal amplitude in an area comprising Persian Gulf, Strait of Hormuz, Gulf of Oman and Arabian Sea. Finite volume method is used in this model to discretize the hydrodynamic equations on triangular mesh. Uniform mesh is used with a resolution of 5 km in the model.The constant values of eight diurnal and semidiurnal tidal components are prescribed along the open boundary. In order to validate the model results, after applying harmonic analysis on the model outputs in desired stations, the achieved amplitude of this analysis compared with results which are obtained from the analysis on the available measurement data in these stations. According to the measurement and model results in these stations, meanwhile identifying the four main tidal components, the amplitude pattern of these components was determined in the whole domain. Also, by using amplitude of main components and estimating of F factor, the type of tide was predicted in the study area. Moreover, studying the maximum amounts of tidal velocity in the study area shows that the amount of this velocity in the Gulf of Oman and Arabian Sea is less than 0.1 m/s.
Ahmad Dordizadeh basirabad; Vahid Chegini
Abstract
In this study, SWAN numerical model used to modeling waves and obtain the significant wave height in range of Amirabad seaport of Caspian Sea. To do this, first, a general model to modeling the wave height in the entire Caspian Sea was built. Then the boundary conditions obtained from the general model, ...
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In this study, SWAN numerical model used to modeling waves and obtain the significant wave height in range of Amirabad seaport of Caspian Sea. To do this, first, a general model to modeling the wave height in the entire Caspian Sea was built. Then the boundary conditions obtained from the general model, by using the NEST operation of SWAN model, modeling the local with higher magnification in the area Amirabad Seaport was used. The local models built in the Amirabad, was calibration and verification with waves profile data recorded by buoys deployed in that area. Comparison the results with data measured by the Amirabad buoy shows that modeling done in this area had a good accuracy. Then running the SWAN model for three years and Obtained significant wave height in the desired location. Finally the wave energy obtained from significant wave height.
m n; v ch; m s; a k
Volume 11, Issue 4 , March 2013, , Pages 57-63