جستجوی مقالات مرتبط با کلیدواژه « numerical modeling » در نشریات گروه « مهندسی دریا »

Nearshore is dynamic and constantly affected by the environmental conditions of the sea, on the other hand, it plays a great role in economic-social management issues. The shoreline is also a part of the nearshore that is constantly affected by tide, waves, currents and human activities. Therefore, it is expected that this section will always be accompanied by changes. The first step of any nearshore development and construction is to know the hydrodynamic conditions of the area. In this study, an attempt has been made to investigate the sensitivity of the shoreline of Bandar Lengeh County by considering the height and energy of nearshore waves. Wave height and energy data have been estimated by running the MIKE 21 spectral wave numerical model for a period of 12 months. The results have been obtained with good accuracy compared to ECMWF data. The correlation coefficient and the RMSE are equal to 0.95 and 0.239. The modeling results show that the maximum average height and energy of waves in the shoreline are 0.22 m and 0.21 kW/m, respectively, in the last months of spring and the beginning of summer. Using the fuzzy-gamma logic and considering the gamma coefficient as 0.9, shoreline sensitivity to variables has been estimated and finally divided into three classes High, moderate, and low. 20% of the shoreline is in the high class, and 23% and 57% of the shoreline are in the moderate and low class, respectively.

Offshore open intakes are built to supply feed water for desalination plants, power plants, and many other coastal industries. They have positive effects on supplying water demands for the coastal cities, however, adverse effects on the life of marine organisms and their habitats have been reported. As the barnacles and biofouling may change the roughness of the intake opening, in this study, their effects on changing roughness from 0.001, 0.19 and 0.5 mm were numerically simulated and the intake performance, including flow velocity between screen rods and flow rate, were evaluated. Changes in flow velocity around the opening of the intake show that an increase in roughness will decrease flow velocity and flow rate up to 4 percent

Coastal walls (dyke) are one of the methods of protecting the coast against coastal erosion and destructive forces of waves. The purpose of this study is to simulate the wave collision with the coastal dyke and compare the results with the laboratory model. Open FOAM open source software and K-ω SST turbulence model were used to simulate the amount of wave consumed by the coastal dyke. Taking into account the different conditions for modeling, a total of 45 experiments were selected to run the program. Modeling was performed in two general conditions with and without structures and for 3 heights of the structure, 3 different positions of the structure and 5 wave heights. The results showed that the absorption of forces has increased compared to the unstructured state and it can be said that the presence of the structure has been able to play a role in the dissipation of wave force up to 10 times compared to the unstructured state. The intensity of force changes in the structure is a function of wave height and this effect decreases with increasing wave height. Under different wave heights, the farther the structure is from the wave generating tank, the less force is applied to the structure.

The trimaran is a multi-hull float consisting of a long, slender main body with two smaller side hulls, and a transverse deck connects the side hulls to the main hull. Trimaran vessels have been studied by designers due to their unique configuration, low resistance at high speeds, transverse stability and good navigation. Also, due to the possibility of special location of the equipment due to the existence of a wide transverse deck and as a result of high transport capacity, the owners of the marine industry have paid special attention to it and extensive research has been done on it. Most of these studies focus on the hydrodynamic parameters of this vessel and there are very few comprehensive and reliable studies on the subject of structural fatigue strength. The phenomenon of fatigue in the transverse deck of the Trimaran float is very important due to the special structure and consequently the intensity of the stresses, and therefore the evaluation of fatigue strength in the preliminary design stage of the float is quite critical. In this paper, a Trimaran vessel is designed according to the operational needs of the Navy and is modeled in Mastro software. Using the software wave module, hydrodynamic analysis was performed at different floating speeds and different angles of the wave on the float and the pressure distribution on the hull was obtained. In the next step, this pressure distribution is applied to the floating body in Mastro finite element software and fatigue analysis is analyzed on the transverse deck using the limit analysis module. The results showed that the amount of fatigue damage at the junction of the front of the transverse deck to the main body at zero speed and chest and oblique waves of the chest has the highest amount compared to other points, which decreases with increasing speed. It was also found that the side waves have the least amount of fatigue damage compared to other angles of the wave collision.

Nowadays, due to the occurrence of devastating earthquakes and the destruction of existing structures especially important structures such as earth dams, and the resulting human and financial risks, the study of the dynamical behavior of these structures is of particular importance. Alavian earthen dam is located upstream of Maragheh city, which in case of an earthquake and endangering the safety of the dam due to possible earthquakes, will seriously affect the residential areas and facilities downstream. The aim of the present study is to investigate the possibility of the dam settlement due to the earthquake and the loss of the freeboard height, resulting in its possible failure. In this regard, the dam body and foundation of Alaviyan dam were modeled using Flac2D software and analyzed under static and dynamic loads. For dynamic analysis of the dam, the seismosignals of Tabas and Ahar-Varzeqan earthquakes were applied as near-field earthquakes and Kocaeli earthquake of Turkey as far-field earthquake. The stress and displacement values obtained from static analyzes were compared with the measured values of the instruments installed in the dam body and good compatibility was observed between them. The results of dynamic analyses showed that the displacements caused by Varzeqan and Kocaeli earthquakes were very low, but the displacement due to Tabas earthquake was high. Also, comparing the results of dynamic analyses at first impounding condition and with considering reservoir water at normal level showed that with increasing water level within the reservoir leads to decrease of displacements.

Feedwater supply for coastal desalination plants, powerplants and other coastal industries using marine intakes has become a common approach during last years. Besides providing water with high quality, intake design should be economically and environmentally acceptable too. The intakes are generally divided into two groups i.e. direct and indirect intakes. The efficiency of direct intakes is a function of sea conditions such as the changes in seawater level and the hydrodynamic of the waves and tides. In deep intakes, the size of the cap, changes in seawater level, and consequently changes in water inflow are challenging design parameters. Seawater level changes due to tides, and the potential effects of climate change and global warming can disrupt the functionality of deep intake systems. In this study, the effect of sea-level changes on the performance of deep intakes has been investigated by studying the hydraulics of the velocity cap along the nearfield. So, an experimental and computational fluid dynamics model has been developed to investigate flow regimes at the location of the velocity cap, vicinity of the surface, and at the sea floor. Density stratification, wave effects, and ambient current have been ignored, so the simulations only developed for stagnant and non-stratifield conditions.

In this paper, a numerical study was conducted to study the effect of the liquid phase compressibility variability in the two-fluid single-pressure model. The two-fluid model is solved by a class of conservative shock-capturing method.The two-fluid model is solved once with the assumption that the density of the liquid phase and one is assumed, assuming that the liquid phase density is varied. In order to examine the compressibility effect, the liquid phase density of the three sample problems was used with different pressure conditions. The results show that, under atmospheric conditions, variations in the density of the liquid phase can be neglected and have no effect on the accuracy of the results of the two-fluid single-pressure model. In the case of extreme pressure gradients, the variability of the liquid phase density in a two-fluid single-pressure model causes deviation of numerical results. Therefore, in the case of extreme pressure gradients, two-fluid single-pressure model is a more accurate model assuming that the liquid phase density is constant.

The most important and expensive portion of basic study of onshore and offshore projects include the measurement of wave characteristics. In Iran, however, will not the data collected are solely applied for the calibration and verification of the numerical modeling. Analysis and interpretation of field data independently or in combination with numerical models determine the general state of oceanographic pparameters. The general pattern of waves, their origin, seasonal variation and statistical distribution of height, period and their direction particularly provides valuable information for management concerns and engineering purposes. In this article the wave field data from five stations along the northern coast of Oman sea in the one-year period is considered for processing, analysis and interpretation. The variation of wave pattern from the entrance of Oman sea to strait Hormuz along the northern coast of Oman sea is studied based on the field data. Moreover, the results are compared with the results of both the ISWM numerical model and the simulation of Hormozgan coastline waves. Prediction of wave pattern and their origin and the variation of wave energy throughout the Oman Sea coastline are from the advantages of this study.

To analyze the behavior of fluids around obstacles cylinder to reduce costs, reduce the time to achieve the results and analysis of boundary conditions to the numerical simulation using FLUENT software Rvym.dr paper, Unsteady Flow, two-dimensional, incompressible intended for each Reynolds static pressure contours, Vorticity, flowing lines and speed has been obtained.It can be seen that the rectangular cylinder pressure at the inlet of the circular cylinders and more triangular and wherever is made of vortices And in which the pressure Darym.dr least the low pressure flow lines will be able to lose your makeup.Also generally at high Reynolds numbers for all cases, and in this case also during the more turbulent flow vortices more.The main gates of the high-pressure occur at these points there is no vortices and flow irregularities.It is known that the contours pressure cylinder with a rectangular cross-sectional area drag to endure more.

Occurrence of water scouring phenomenon around hydraulic structures is one of the most essential factors that destroys and consequently losses of the financial each year. Existence of pier structure in front of the entrance of harbor, causes to generate three dimensional (3-D) flows around the piles of piers (due to entrance of wave into the harbor and the result of ships movements) and causes erosion, sedimentation of basin and localized water scouring. In numerical modelings that have been done so far, rate of water scouring is a function of flow parameters such as flow velocity, depth and geometrical parameters like diameter of the piles and granulation. In this paper, in addition to the study of previous parameters, we can estimate amount of affect of rotation in water scouring process around the piles of piers. In this article, according to the existence of 3-D flows around hydraulic structures such as downwards flows in front of piles and in order to consider the role of flows in water scouring a complete 3-D model is used for hydraulic flow simulation around the structures. To consider the actual boundaries of the piles of piers, the structural mesh and curvelinear border method (along the horizontal and vertical) is used. Due to changes in depth and sea bottom, the Sigma coordinate system is used to mesh.

Tsunami waves happen every year in different locations of the seas and oceans of the world. These waves propagate with high celerity in different directions and when these waves reach the coast cause serious damage to the beach، coastal structures and facilities. Therefore understanding this complicated phenomenon and prediction of its behavior can minimize the damages. In this research a numerical simulation was performed on tsunami phenomenon. The objective of the research was to predict the wave characteristics as it reaches the coastal zone. Flow3D software was used for this purpose. Assuming viscous flow for sea water، Navier Stokes as governing equations together with volume of fluid method was used to simulate tsunami waves in FLOW 3D software. A single wave was generated using a simulated piston type wave maker in the lateral boundary of the study domain. Waves are generated in deep water and propagate towards the beach. The simulation results revealed the considerable increase in wave height in coastal zone. The rate of height increase versus slope was calculated. Furthermore effect of decrease in width of the coastal zone on wave height increase was considered.

When studying the structural response of rubble mound breakwaters to wave loading، the knowledge of water surface fluctuations، pore pressure variations and related wave attenuation inside the porous structure is important since the pore pressures affect most responses، such as wave run-up، wave overtopping، reflections، transmission and the hydraulic and geotechnical stability of the breakwater. For this purpose a numerical model was developed to investigate the water surface and pressure fluctuations outside and inside the statically conventional rubble mound breakwater by using FLOW-3D software. The water - structure interaction is obtained by model to simulate the corresponding turbulence field and volume of fluid (VOF) theory to simulate the free surface. The comparison between numerical and experimental results shows a good agreement in terms of both water surface and pore pressure Fluctuations in conventional rubble mound breakwaters.

Nowadays increase in earth population leads to the increase in energy consumption which is mainly has fossil resources. This in turn causes a reduction in oil and gas reservoirs, increase in their prices and creating greenhouse gases and air pollution. These problems draw the attention of scientists for use of clean energy resources. One of these resources is ocean wave energy. There are different plans for ocean wave energy absorption in the world. However most of them are in study stages and have not been approved for bulk production. In this paper the feasibility of absorbing sea wave energy by oscillating water column (OWC) system in the southern coast of Iran is studied. For this purpose wave interaction with this device is numerically modeled. Then four probable waves in Persian Gulf with different heights have been selected as input to the model. The results showed that if the input wave height to the system increases by 10%, the power of the device can be increased by 40%.