A short cut numerical method for determination of periods of free oscillations for basins with irregular geometry and bathymetry

A short cut numerical method for evaluation of the modes of free oscillations of the basins which have irregular geometry and bathymetry is presented in this paper. In the method, a single wave is inputted to the basin as an initial impulse. The respective agitation in the basin is computed by using the numerical method solving the nonlinear form of long wave equations. The time histories of water surface fluctuations at different locations due to propagation of the waves in relation to the initial impulse are stored and analyzed by the fast Fourier transform technique (FFT) and energy spectrum curves for each location are obtained. The frequencies of each mode of free oscillations are determined from the peaks of the spectrum curves. The method is tested by using regular shaped flat bottom basins with different depths. The computed periods of free oscillations are compared with the theoretical values. The accuracy and performance of the method are discussed. As a case study for the application to the basins of irregular shape and bathymetry, the periods of free oscillations of the sea of Marmara is determined and discussed.


A numerical and experimental study of local hydrodynamics due to interactions between a solitary wave and an impervious structure
Arabi, Mahsa Ghazian; Sogut, Deniz Velioglu; Khosronejad, Ali; Yalçıner, Ahmet Cevdet; Farhadzadeh, Ali (Elsevier BV, 2019-05-01)
A series of experiments and numerical simulations on the interactions between a solitary wave and an impervious structure of square cross-section (block) in relatively shallow water were conducted to shed light on the physical processes of origination and evolution of coherent structures induced during such events. The block was placed at two different positions in a laboratory flume and was exposed to a solitary wave. The flow fields around the block were measured spatially and temporally for the validatio...
A new modal superposition method for nonlinear vibration analysis of structures using hybrid mode shapes
Ferhatoglu, Erhan; Ciğeroğlu, Ender; Özgüven, Hasan Nevzat (Elsevier BV, 2018-07-01)
In this paper, a new modal superposition method based on a hybrid mode shape concept is developed for the determination of steady state vibration response of nonlinear structures. The method is developed specifically for systems having nonlinearities where the stiffness of the system may take different limiting values. Stiffness variation of these nonlinear systems enables one to define different linear systems corresponding to each value of the limiting equivalent stiffness. Moreover, the response of the n...
A two dimensional euler flow solver on adaptive cartesian grids
Siyahhan, Bercan; Aksel, Mehmet Haluk; Department of Mechanical Engineering (2008)
In the thesis work, a code to solve the two dimensional compressible Euler equations for external flows around arbitrary geometries have been developed. A Cartesianmesh generator is incorporated to the solver. Hence the pre-processing can be performed together with the solution within a single code. The code is written in the C++ programming language and its object oriented capabilities have been exploited to save memory in the data structure developed. The Cartesian mesh is formed by dividing squares succe...
An accurate nonlinear 3d Timoshenko beam element based on Hu-Washizu functional
Soydas, Ozan; Sarıtaş, Afşin (Elsevier BV, 2013-09-01)
An accurate 3d mixed beam element that is efficient especially in nonlinear analysis is presented in this paper. The mathematical theory is based on Hu-Washizu principle that uses three-fields in the variational form. The composition of the variational form ensures independent selection of displacement, stress and strain fields. Timoshenko beam theory is extended to three dimensions for deriving strains from displacement field. Numerical integration of stress strain relations along control sections is carri...
A Mechanistic Model for Predicting Frictional Pressure Losses for Newtonian Fluids in Concentric Annulus
SORGUN, MEHMET; Ozbayoglu, M. E. (Informa UK Limited, 2010-01-01)
A mathematical model is introduced estimating the frictional pressure losses of Newtonian fluids flowing through a concentric annulus. A computer code is developed for the proposed model. Also, extensive experiments with water have been conducted at Middle East Technical University, Petroleum and Natural Gas Engineering Department Flow Loop and recorded pressure drop within the test section for various flow rates. The performance of the proposed model is compared with computational fluid dynamics (CFD) soft...
Citation Formats
A. C. Yalçıner, “A short cut numerical method for determination of periods of free oscillations for basins with irregular geometry and bathymetry,” OCEAN ENGINEERING, pp. 747–757, 2007, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/38644.