International Journal of coastal and offshore engineering
http://ijcoe.org
International Journal of Coastal and Offshore Engineering - Journal articles for year 2017, Volume 1, Number 2Yektaweb Collection - http://www.yektaweb.comen2017/9/10Investigation of Water Circulation And Temperature Effect In Indian Ocean By Perturbation Method
http://ijcoe.org/browse.php?a_id=42&sid=1&slc_lang=en
<p style="margin-left:3.75pt;">The tropical Indian Ocean forms the major part of the largest warm pool on Earth, and its interaction with the atmosphere plays an important role in shaping climate on both regional and global scales. Three dimensional temperature and velocity fields are calculated analytically for an ocean forced by wind stress and surface heat flux. A basic thermal state involving a balance of lateral and vertical heat diffusion is assumed. The wind stress is chosen such that a tropical mass transport gyre is generated. An effect of nonlinear heat advection is calculated by a perturbation method. This circulation is closed through thin up and downwelling layers at the sides. Superimposed there is a barotropic wind driven circulation, with a transport field of the type described by Munk. The interior temperature field to the next order is affected not only by interior heat advection but by heat advection in the Ekman layer, in the up and downwelling layers and in the main western boundary current. We have compared Sepherical and Cartesian computational results.</p>
Mojgan Ghazi MirsaeidPrognosis of Time to Failure of Corroding Pipelines
http://ijcoe.org/browse.php?a_id=45&sid=1&slc_lang=en
<p>The oil and gas pipelines are significant assets in Iran. However, these assets are subject to degradation from corrosion. Corrosion causes gradual thinning of the pipelines’ wall leading to leaks or bursts. Allowing a corroding pipeline to continue operation may lead to a finite risk of exceeding the limit state of burst. Codes of practice, such as Modified ASME B31G [1] and DNV F101 [3], among others, have developed relationships to determine the bursting pressure of corroded pipelines. The purpose of this paper is to develop, test, and illustrate a simple spreadsheet-based probabilistic procedure that can be used by practicing engineers to determine the Remaining Useful Life (RUL) of a corroding pipeline, following its first inspection. Modified ASME B31G and DNV F101 equations are used to illustrate this method. As new inspection data regarding the extent of corrosion becomes available, the results can be updated and a new probability of failure obtained. The calculated probability of failure is then compared with the target values to determine the remaining life. The approach is equally applicable to both onshore and offshore oil and gas pipelines. </p>
Sirous YasseriIntroducing a Method for More Precise Prediction of Berth Occupancy Ratio in Bulk Liquid Terminals
http://ijcoe.org/browse.php?a_id=46&sid=1&slc_lang=en
<p>Existing methods presented in references and standards for calculation of berth occupancy ratio, are more concentrated on container terminals. However, some empirical formulas can be found to predict the berth occupancy, but these methods are neither accurate enough nor economically wise to be employed for the prediction of berth occupancy ratio in large and complex bulk liquid terminals. Therefore, it is attempted in this paper to introduce a method for more precise prediction of berth occupancy ratio for bulk liquid terminals. In the proposed method for calculation of berth occupancy ratio in bulk liquid terminals, times which is not used for loading/unloading operation is investigated. The loading/unloading lost factor is considered in calculations in order to calculate the operational value for loading/unloading rate. Next, practical values for these items are given based on previous authors’ experiences. Finally, a case study is performed for a liquid bulk petrochemical terminal to specify the presented method. Results show 24% difference between new method and old empirical formulas.</p>
Said MazaheriTsunami Assessment for Inundation Risk Management at Chabahar Bay Facilities in Iran
http://ijcoe.org/browse.php?a_id=26&sid=1&slc_lang=en
<p class="Default" style="margin-right:3.85pt;text-align:justify;text-justify:
inter-ideograph;text-indent:14.25pt;line-height:150%"><span new="" style="font-family: " times="">In this study two numerical models, one a regional generation and propagation model and the other an inundation model, have been applied to the problem of examining the impact that a large, locally generated tsunami could have on Chabahar Bay facilities in Iran. To</span><span lang="EN-GB" new="" style="font-family: " times=""> achieve a realistic outlook of tsunami hazards in the area</span><span new="" style="font-family: " times="">, the generation, propagation and interaction of tsunami waves with Chabahar Bay coasts is being numerically modeled for specific events. The modeling is performed using the numerical code which solves the nonlinear Boussinesq wave equations. Results of numerical simulations performed in this study considering past tsunami occurrence records indicate that the multipurpose Chabahar Port is expected to experience the tsunami events with heights ranging between 8 to 10 meters. The model gives approximately the observed maximum area of flooding of Chabahar City. The large amount of flooding of Chabahar city coasts, Iran from the 9.1 magnitude earthquake and small amount of flooding from the 8.3 magnitude earthquake achieved and extensively flooding Chabahar City was reproduced by the numerical model. The effect of the tide was modeled and found to be small.</span><span new="" style="font-family: " times=""> </span><span new="" style="font-family: " times="">The results of this study are intended for emergency planning purposes. Appropriate use would include the identification of evacuation zones. The results are used also to find a best configuration advice for the urban facilities in order to mitigate tsunami related risks, with positioning such facilities at the Western Cape of the bay. </span></p>
Mahmood Reza Akbarpour JannatSimulating wave-structure interactions using a modified WCSPH scheme
http://ijcoe.org/browse.php?a_id=37&sid=1&slc_lang=en
<p>A weakly compressible SPH (WCSPH) scheme has been developed to simulate interaction between waves and rigid bodies. The developed WCSPH scheme is improved by applying a modified equation to calculate the wave-structure interaction, in order to increase its accuracy. The effects of relative fluid/solid particles’ acceleration are considered in the modified equation. To evaluate the efficiency of developed model, the dynamics of structural movements and related pressure fields are investigated for several test cases and the results are compared with the experimental data. It seems that the modified algorithm is able to improve the accuracy of simulated wave-structure interactions.</p>
Ahmad Reza Mostafa GharabaghiIntroduction of a Simple Cnoidal Wave Formulation Based on Nonlinear Interaction of Wave-Wave Principles
http://ijcoe.org/browse.php?a_id=50&sid=1&slc_lang=en
In this study, a simple and efficient approach based on nonlinear wave interaction fundamentals is theoretically proposed to generate surface profile of the cnoidal waves. The approach includes Newton-Raphson algorithm to calculate the Ursell parameter and using a simple formulation. The wave profile resulted by means of introduced approach is determined as a superposing of limited number of cosine harmonics without encountering difficulties of using elliptic or hyperbolic functions, or any complex and complicated differential equations. It is demonstrated that a cnoidal wave profile is a result of high order self nonlinear interaction of primary frequency. Some definite energy is transmitted to higher harmonics due to nonlinear interactions. The amount of transmitted energy is controlled by Ursell parameter. The desirable accuracy determines the number of included harmonics in the proposed formulation and relative error of approach can be predicted based on Fourier and least square analysis techniques. The outputs of the proposed method are verified with cnoidal resulted from elliptic functions and the high efficiency of new approximation is revealed for engineering applications. The calculation of wave parameters such as energy flux, volume flux and radiation stress for cnoidal wave can be approximated using the proposed method. Using this approach, a physical interpretation of the <em>B<sub>m</sub></em> parameter (introduced in the first order of cnoidal wave theory) is presented. The calculation of several parameters such as velocity vectors and dynamic pressure duo to cnoidal waves is very simple by means of proposed approach.Seyed Masoud Mahmoudof