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Development of a Model to Investigate Energy Production Potential from Sea Applying GIS Technique
, M.Sc. Thesis Sharif University of Technology ; Abbaspour, Majid (Supervisor)
Abstract
The growing requirements for renewable energy production lead to the development of a new series of systems, including wave and tidal energy conversion systems. Due to their sensitivity and the impact of the aggressive marine environment, the selection of the most adequate location for these systems is a major and very important task. Several factors, such as technological limitations, environmental conditions, administrative and logistic conditions, have to be taken into account in order to support the decision for best location. The aim of the present study is to provide an Atlas of IRAN Offshore Renewable Energy Resources (hereafter called ‘the Atlas’) to map out wave and tidal resources...
Effect of Aquatic Plants on Hydrodynamic and Dispersion in the Wave Motion
, Ph.D. Dissertation Sharif University of Technology ; Jamali, Mirmosadegh (Supervisor)
Abstract
Aquatic plants play an important role in water environment. Increasing drag force, distorting the velocity and turbulence structures and other related parameters, are the results of the presences of plants. These changes affect the dispersion and mass transport in the aquatic areas. This thesis presents laboratory visualizations and measurements of wave motion, and passive solute surface dispersion (longitudinal and lateral) in arrays of cylinders, a model for emergent, rigid aquatic plants. In the range of (where is Keulegan–Carpenter number, is the maximum oscillatory velocity perpendicular to the cylinder axis, is the period of oscillation, and is the diameter of the cylinder), and (where...
An EWA framework for the probabilistic-based structural integrity assessment of offshore platforms
, Article Marine Structures ; Volume 59 , 2018 , Pages 60-79 ; 09518339 (ISSN) ; Yaghubi Namin, Y ; Matin Nikoo, H ; Estekanchi, H ; Kimiaei, M ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
Endurance Wave Analysis (EWA) is a novel, simple, economical but yet reliable method for the integrity assessment of offshore platforms against extreme irregular waves. The current paper presents a framework for the probabilistic assessment of offshore platforms based on EWA. The stochastic nature and the uncertainties in the ocean waves were taken into account by introducing a set of artificial, random and gradually intensifying wave trains. To simulate other uncertainties in the loading and the strength of the structure a Latin Hypercube Sampling (LHS) type of Monte Carlo Simulation (MCS) was employed. The EWA methodology and different structural performance criteria were considered. The...
A novel shape memory alloy-based element for structural stability control in offshore structures under cyclic loading
, Article Ships and Offshore Structures ; Volume 15, Issue 8 , 2020 , Pages 844-851 ; Alam, M. S ; Seethaler, R. J ; Zabihollah, A ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
Wind and ocean waves highly influence the performance and functionality of structures, requiring an efficient control element. The structural behavior of one of the most recent structural control elements, namely shape memory alloys (SMA)-based control element, under cyclic loadings of oceans waves, has been investigated. Shape memory alloys are one of the attractive smart materials with the ability to return to the initial shape after experiencing large deformation. Experimental tests have been conducted to study the effects of cyclic loads on several specimens of the SMA wires. The SMA wires are being used in the SMA-based structural control system to dissipate the energy of external...
Numerical modeling of subaerial and submarine landslide-generated tsunami waves—recent advances and future challenges
, Article Landslides ; Volume 13, Issue 6 , 2016 , Pages 1325-1368 ; 1612510X (ISSN) ; Ataie Ashtiani, B ; Sharif University of University
Springer Verlag
Abstract
Landslide-generated waves (LGWs) are among natural hazards that have stimulated attentions and concerns of engineers and researchers during the past decades. At the same period, the application of numerical modeling has been progressively increased to assess, control, and manage the risks of such hazards. This paper represents an overview of numerical studies on LGWs to explore associated recent advances and future challenges. In this review, the main landslide events followed by an LGW hazard are scrutinized. The uncertainty regarding landslide characteristics and the lack of data concerning generated tsunami properties highlights the necessity of probabilistic analysis and numerical...
Simulation of wave generated by landslides in Maku dam reservoir
, Article Prediction and Simulation Methods for Geohazard Mitigation - Proceedings of the International Symposium on Prediction and Simulation Methods for Geohazard Mitigation, IS-KYOTO 2009, 25 May 2009 through 27 May 2009 ; 2009 , Pages 91-96 ; 9780415804820 (ISBN) ; Ataie Ashtiani, B ; Sharif University of Technology
Abstract
In this work, impulsive wave generation and propagation generated by landslides are studied numerically for a real case. Maku dam reservoir, in the northwestern of Iran is considered as the case study. Generated wave heights, wave run-up, maximum wave height above the dam crest and the probable overtopping volume have been evaluated, using a two-dimensional numerical model (LS3D). This model is validated using available three-dimensional experimental data for simulating impulsive wave caused by sub-aerial landslides. Based on the results, the generated wave height for first and second scenarios are 12 m and 18 m respectively. The wave height of 8 m is observed close to dam body. Because of...
Dispersion around a circular cylinder in surface wave motion
, Article Scientia Iranica ; Vol. 21, issue. 3 , 2014 , p. 548-556 ; 10263098 ; Jamali, M ; Sharif University of Technology
Abstract
In this paper, we examine fluid flow and associated dispersion around a circular cylinder under progressive surface wave motion. The flow field and vortex shedding patterns were studied using flow visualization and Particle Image Velocimetry (PIV). Several patterns of vortex shedding were identified around a single cylinder. The vortex shedding patterns under progressive wave motion are similar to those observed in planar oscillatory flow, except in the way the vortices form and in the orientation they take. The observed vortex patterns in progressive wave motion are more unstable than those in planar oscillatory flow. Using particle tracking and the Lagrangian dispersion method, the...
Analytical cubic solution to weakly nonlinear interactions between surface and interfacial waves
, Article Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE, 31 May 2009 through 5 June 2009, Honolulu, HI ; Volume 6 , 2009 , Pages 625-630 ; 9780791843468 (ISBN) ; Jamali, M ; Sharif University of Technology
Abstract
Resonant interaction between one surface wave and two oblique interfacial waves is analyzed in a three dimensional system of a finite-depth, two-layer fluid. A third order perturbation analysis is carried out to obtain the evolution equations of the waves amplitudes. Taking the waves amplitudes as the perturbation small parameter, the evolution equations of the waves are solved simultaneously to obtain the short and long term behavior of the interfacial waves. In contrast to the second order analysis, the current analysis shows that after an initial exponential growth period, the interfacial waves stop growing and stabilize. Furthermore, the influences of surface wave frequency, density...
Second-order perturbation added mass fluctuation on vertical vibration of tension leg platforms
, Article Marine Structures ; Volume 19, Issue 4 , 2006 , Pages 271-283 ; 09518339 (ISSN) ; Golafshani, A. A ; Seif, M. S ; Sharif University of Technology
2006
Abstract
Total motion in waves can be considered as a superposition of the motion of the body in still water and the forces on the restrained body. In this study the effect of added mass fluctuation on vertical vibration of tension leg platforms (TLP) in the case of vibration in still water for both free and forced vibration subjected to axial load at the top of the leg is presented. This effect is more important when the amplitude of vibration is large. Also this is important in fatigue life study of tethers. The structural model used here is very simple. Perturbation method is used to formulate and solve the problem. First- and second-order perturbations are used to solve the free and forced...
Comprehensive study on the results of tension leg platform responses in random sea
, Article Journal of Zhejiang University: Science ; Volume 7, Issue 8 , 2006 , Pages 1305-1317 ; 10093095 (ISSN) ; Golafshani, A. A ; Seif, M. S ; Sharif University of Technology
2006
Abstract
Compliant offshore structures are used for oil exploitation in deep water. Tension leg platform (TLP) is a suitable type for very deep water. The nonlinear dynamic response of TLP under random sea wave load is necessary for determining the maximum deformations and stresses. Accurate and reliable responses are needed for optimum design and control of the structure. In this paper nonlinear dynamic analysis of TLP is carried out in both time and frequency domains. The time history of random wave is generated based on Pierson-Moskowitz spectrum and acts on the structure in arbitrary direction. The hydrodynamic forces are calculated using the modified Morison equation according to Airy's linear...
Simple model for exact heave motion of tension leg platform
, Article WSEAS Transactions on Mathematics ; Volume 5, Issue 5 , 2006 , Pages 500-506 ; 11092769 (ISSN) ; Golafshani, A. A ; Seif, M. S ; Sharif University of Technology
2006
Abstract
In this paper the dynamic response of the leg of a tension leg platform (tether) subjected to the load simulated as ocean wave at the top of the leg is presented. The structural model is very simple but several complicated factors such as foundation effect, buoyancy and simulated ocean wave load are considered. Two continuous models are proposed to present the structural system and the mentioned effects. The problem is solved by means of non-harmonic Fourier expansion in terms of eigenfunctions obtained from a non-regular Sturm-Liouville system
Wave interaction pitch response of tension leg structures
, Article 13th International Congress on Sound and Vibration 2006, ICSV 2006, Vienna, 2 July 2006 through 6 July 2006 ; Volume 5 , 2006 , Pages 3508-3515 ; 9781627481502 (ISBN) ; Ataie Ashtiani, B ; Seif, M. S ; Golafshani, A. A ; Sharif University of Technology
2006
Abstract
Because of fluctuation in leg tension, pitch motion is very effective in fatigue and life safety of leg elements in tension leg structures (TLSs). In this paper exact solution for pitch vibration of a TLS interacting with ocean wave is presented. The legs are considered as elastic springs. The flow is assumed to be irrotational and single-valued velocity potentials are defined. The effects of radiation and scattering are considered in the boundary value problem. Because of linear behavior of legs during wave excitation, ignoring coupling effects with other degrees of freedom, the analytical solution of pitch response has good agreement with the real behavior of the structure
Seismic analysis of a system of dam-massed foundation-reservoir under inclined excitation
, Article JVC/Journal of Vibration and Control ; 2021 ; 10775463 (ISSN) ; Ghaemian, M ; Sharif University of Technology
SAGE Publications Inc
2021
Abstract
One of the acceptable assumptions in engineering practice is vertical propagation of earthquake waves. When the source of earthquake is located very deep in the ground, this assumption is valid, but for sources located in shallow ground, it loses its viability. In this study, linear seismic analysis of a system of concrete dam-massed foundation-reservoir is performed under inclined earthquake excitation. Both P- and SV-type earthquakes are considered for the purpose of the seismic analysis. To consider the effects of inhomogeneous waves for the case of SV wave propagation, post-critical angles are also considered in the analysis. To investigate the effects of earthquake frequency content on...
Seismic analysis of a system of dam-massed foundation-reservoir under inclined excitation
, Article JVC/Journal of Vibration and Control ; Volume 28, Issue 13-14 , 2022 , Pages 1769-1780 ; 10775463 (ISSN) ; Ghaemian, M ; Sharif University of Technology
SAGE Publications Inc
2022
Abstract
One of the acceptable assumptions in engineering practice is vertical propagation of earthquake waves. When the source of earthquake is located very deep in the ground, this assumption is valid, but for sources located in shallow ground, it loses its viability. In this study, linear seismic analysis of a system of concrete dam-massed foundation-reservoir is performed under inclined earthquake excitation. Both P- and SV-type earthquakes are considered for the purpose of the seismic analysis. To consider the effects of inhomogeneous waves for the case of SV wave propagation, post-critical angles are also considered in the analysis. To investigate the effects of earthquake frequency content on...
Numerical investigation of the stability of armour units in low-crested breakwaters using combined SPH–Polyhedral DEM method
, Article Journal of Fluids and Structures ; Volume 81 , 2018 , Pages 14-35 ; 08899746 (ISSN) ; Pak, A ; Sharif University of Technology
Academic Press
2018
Abstract
Low-crested breakwaters have become more attractive because they do not hinder the beautiful coastal landscape and are more environmentally friendly comparing to traditional breakwaters. The available formulae for design of these types of structures mainly focus on wave transmission, reflection and dissipation aspects. However, stability of the armour blocks are not directly taken into account in the design process. In this study the Lagrangian meshfree method of SPH along with a discrete element method i.e. Polyhedral DEM are used to simulate the interaction between the sea water waves with different characteristics and low-crested breakwaters constructed using cubic armour blocks. SPH is...
A technique for detection of interfacial waves forming a two-dimensional pattern
, Article Fluid Dynamics Research ; Vol. 46, issue. 1 , 2014 ; ISSN: 01695983 ; Fazeli M ; Jamali, M ; Sharif University of Technology
Abstract
In this paper, we consider resonant interaction between a surface wave and sub-harmonic interfacial waves forming a two-dimensional pattern at the interface between two fluid layers. The resulting interfacial pattern changes both in time and space. An image processing technique is proposed to extract information about the evolution of the component interfacial waves in a wave flume. The technique proved to give accurate and consistent results when applied to different stages of the interaction. The experimental measurements were used to verify the theoretical predictions. The method can be used for detection of some other wave motions
Acoustic resonance scattering from a multilayered cylindrical shell with imperfect bonding
, Article Ultrasonics ; Volume 49, Issue 8 , 2009 , Pages 682-695 ; 0041624X (ISSN) ; Hasheminejad, S. M ; Sharif University of Technology
Abstract
The method of wave function expansion is adopted to study the three dimensional scattering of a time-harmonic plane progressive sound field obliquely incident upon a multi-layered hollow cylinder with interlaminar bonding imperfection. For the generality of solution, each layer is assumed to be cylindrically orthotropic. An approximate laminate model in the context of the modal state equations with variable coefficients along with the classical T-matrix solution technique is set up for each layer to solve for the unknown modal scattering and transmission coefficients. A linear spring model is used to describe the interlaminar adhesive bonding whose effects are incorporated into the global...
Lattice Boltzmann method for simulating impulsive water waves generated by landslides
, Article Scientia Iranica ; Vol. 21, issue. 2 , 2014 , p. 318-328 ; 1026-3098 ; Sarfaraz, M ; Sharif University of Technology
Abstract
Impulsive water waves generated by landslides impose severe damage on coastal areas. Very large mass ows in the ocean can generate catastrophic tsunamis. Preventing damage to dams and coastal structures, and saving the lives of local people against landslide-generated waves, has become an increasingly important issue in recent years. Numerical modeling of landslide-generated waves is a challenging subject in CFD. The reason lies in the difficulty of determining the interaction between the moving solids and sea water, which causes complicated turbulent regimes around the moving mass and at the water surface. Submarine or aerial types of landslide can further complicate the problem. Up to now,...
Develop of a fully nonlinear and highly dispersive water wave equation set; analysis of wave interacting with varying bathymetry
, Article Prediction and Simulation Methods for Geohazard Mitigation - Proceedings of the International Symposium on Prediction and Simulation Methods for Geohazard Mitigation, IS-KYOTO 2009, 25 May 2009 through 27 May 2009, Kyoto ; 2009 , Pages 213-218 ; 9780415804820 (ISBN) ; Ataie Ashtiani, B ; Sharif University of Technology
Abstract
Extended Boussinesq-type water wave equations are derived in two horizontal dimensions to capture the nonlinearity effects and frequency dispersion of wave in a high accuracy order. A multi-parameter perturbation analysis is applied in several steps to extend the previous second order Boussinesq-type equations in to 6th order for frequency dispersion and consequential order for nonlinearity terms. The presented high-order Boussinesq-type equation is applied in a numerical model to simulate the wave field transformation due to physical processes such as shoaling, refraction and diffraction. The models results are compared with available experimental data which obtained in a laboratory wave...
Estimation of near-field characteristics of tsunami generation by submarine landslide
, Article Ocean Engineering ; Volume 35, Issue 5-6 , 2008 , Pages 545-557 ; 00298018 (ISSN) ; Ataie Ashtiani, B ; Sharif University of Technology
2008
Abstract
Underwater landslide can trigger impulsive waves with high amplitude and run-up, which may cause substantial damage. In this work, the experimental investigations are performed to study the impulsive wave characteristics caused by underwater landslides. The effects of landslide geometry and kinematics on wave characteristics are studied by performing 84 laboratory experiments. The influences of thickness, volume and shape of failure mass on the characteristics of initial wave are discussed. The impacts of water body conditions such as the slope of sliding bed and the initial submergence of underwater landslide are also examined. The present experimental data as well as the available data in...