Please use this identifier to cite or link to this item: https://scholarbank.nus.edu.sg/handle/10635/165564
Title: FORCES ON A SMOOTH SUBMARINE PIPELINE IN REGULAR AND RANDOM WAVES
Authors: K. SUBBIAH
Keywords: Submarine pipeline
regular and random wave forces
hydrodynamic coefficients
maximum force and pressure coefficients
period parameter
scattering parameter
gap ratio and depth parameter
Issue Date: 1989
Citation: K. SUBBIAH (1989). FORCES ON A SMOOTH SUBMARINE PIPELINE IN REGULAR AND RANDOM WAVES. ScholarBank@NUS Repository.
Abstract: Forces induced by regular and random waves on a smooth, small / large diameter submarine pipeline, fixed horizontally at various gaps from a plane boundary, are investigated in this thesis. From the regular wave force tests, the in-line hydrodynamic coefficients for a pipeline in the inertia-drag regime are evaluated through the use of Morison equation and the least squares method. The in-line root mean square (rms) coefficient is derived using the Morison equation and the linear wave theory. The maximum and overall (without decomposition) rms transverse force coefficients are determined from the measured forces. Fourier analysis on the transverse forces is carried out and the n-th harmonic transverse rms coefficients for first three harmonic components are computed. The in-line and transverse rms coefficients are combined together to give the combined or total rms coefficients. The in-line and transverse force transfer coefficients and the total rms coefficients are correlated with the Keulegan-Carpenter number or period parameter, gap ratio and depth parameter. The pipeline is subjected to random waves with a P-M spectrum at various energy levels in the random wave force tests. The in-line hydrodynamic coefficients are evaluated using two different methods, one in the frequency domain and the other in the time domain. The transverse hydrodynamic coefficients are evaluated using five different force models and these are compared in terms of the correlation coefficient. The results of the random wave force tests based on the significant wave concept are compared with those of regular wave pipeline conditions. The large diameter pipeline is first considered to be in the predominantly inertial regime, considering the size of the pipe and wave.conditions employed in this phase of the study. The in-line hydrodynamic coefficient of inertia and transverse hydrodynamic coefficients of lift and vertical inertia are evaluated through the use of least squares method. The wave forces and pressures that act on the pipeline in a finite water depth are obtained using Green's second identity formulation for potential functions. The normalized maximum in-line and transverse forces and pressures at salient pressure ports around the pipeline are obtained by solving the resulting integral equation numerically. The numerical results are compared with those of the experimental investigation on wave induced forces and pressures on a large diameter pipeline, placed at various gaps from a plane boundary. The hydrodynamic and maximum force and pressure coefficients are correlated with the scattering parameter, gap ratio and depth parameter. The large diameter pipeline is also subjected to random waves with a P-M spectrum. The hydrodynamic and maximum force and pressure coefficients, obtained from random wave force and pressure tests are compared with those of regular waves under the same pipeline conditions.
URI: https://scholarbank.nus.edu.sg/handle/10635/165564
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