The Wave Induced Motions of a Tension Leg Platform in Deep Water

1981 ◽  
Author(s):  
Tan S. Gie ◽  
W. de Boom
Keyword(s):  
Deep Water ◽  
Tension Leg Platform ◽  
Wave Induced

The Equivalent Depth of Wave-Induced Scour Around Offshore Pipelines

2006 ◽  
Author(s):  
Mir Emad Mousavi ◽  
Abbas Yeganeh Bakhtiary ◽  
Nastaran Enshaei
Keyword(s):  
Deep Water ◽  
Numerical Models ◽  
Scour Depth ◽  
Offshore Pipelines ◽  
Equivalent Depth ◽  
Physical Experiments ◽  
Water Conditions ◽  
Installation Depth ◽  
New Equation ◽  
Wave Induced

Physical experiments have been conducted to study the scouring around a pipe over an erodible bed under waves motion. The results show that the depth of the wave-induced scour is reduced when the pipe is installed in a primary depth. It is also indicated that when the primary installation depth of the pipe, |e|, exceeds a specified depth, no scouring occurs underneath the pipe. This specific depth is called the Equivalent Depth of Wave-Induced scour, Se. The equivalent depth of wave-induced scour is estimated as a function of pipe diameter and the Keulegan Carpenter number. Also for prediction of the scour depth with respect to the primary installation depth of the pipe, a new equation is proposed. In addition, new equations are proposed for prediction of the scour width before the pipe is installed. The results and proposed equations are next simplified in the form of diagrams to be used in practice. The experiments cover small KC numbers (KC < 6) that represent deep water conditions. The results can be used either for the design purposes or for calibration of the numerical models.

scholarly journals Stochastic Response of Tension Leg Platform to Wave and Current Forces

1989 ◽  
Vol 111 (4) ◽  
pp. 221-230 ◽  
Author(s):  
A. Ertas ◽  
J.-H. Lee
Keyword(s):  
Constant Current ◽  
Response Analysis ◽  
Stochastic Dynamic ◽  
Superposition Method ◽  
Random Waves ◽  
Stochastic Response ◽  
Tension Leg Platform ◽  
Single Degree Of Freedom ◽  
Simulation Techniques ◽  
Wave Induced

The linear analysis in the frequency domain is presented for the surge motion of a tension leg platform (TLP) in the case of random waves only and random waves with constant current. A single-degree-of-freedom model of a TLP is employed for response. The superposition method, one of the simulation techniques, is applied to random sea wave, and the response analysis of TLP in time is developed with wave velocity and wave acceleration simulations. Wave-induced forces are calculated using the modified Morison equation, which takes into account relative motion. Computational methods for both analyses are developed, and the results of stochastic, dynamic response of the TLP, with and without the presence of current, are presented and compared.

scholarly journals Experimental study of particle trajectories below deep-water surface gravity wave groups

2019 ◽  
Vol 879 ◽  
pp. 168-186 ◽  
Author(s):  
T. S. van den Bremer ◽  
C. Whittaker ◽  
R. Calvert ◽  
A. Raby ◽  
P. H. Taylor
Keyword(s):  
Gravity Wave ◽  
Deep Water ◽  
Water Waves ◽  
Wave Equations ◽  
Stokes Drift ◽  
Surface Gravity ◽  
Return Flow ◽  
Surface Gravity Wave ◽  
Wave Groups ◽  
Wave Induced

Owing to the interplay between the forward Stokes drift and the backward wave-induced Eulerian return flow, Lagrangian particles underneath surface gravity wave groups can follow different trajectories depending on their initial depth below the surface. The motion of particles near the free surface is dominated by the waves and their Stokes drift, whereas particles at large depths follow horseshoe-shaped trajectories dominated by the Eulerian return flow. For unidirectional wave groups, a small net displacement in the direction of travel of the group results near the surface, and is accompanied by a net particle displacement in the opposite direction at depth. For deep-water waves, we study these trajectories experimentally by means of particle tracking velocimetry in a two-dimensional flume. In doing so, we provide visual illustration of Lagrangian trajectories under groups, including the contributions of both the Stokes drift and the Eulerian return flow to both the horizontal and the vertical Lagrangian displacements. We compare our experimental results to leading-order solutions of the irrotational water wave equations, finding good agreement.

Study Influence on Water and Sediment in Sandbank-Lagoon Harbor

2014 ◽  
Vol 1065-1069 ◽  
pp. 518-521
Author(s):  
Jie He ◽  
Xin Sheng Zhao
Keyword(s):  
South China ◽  
Deep Water ◽  
Wave Power ◽  
The West ◽  
West Side ◽  
Water And Sediment ◽  
And Control ◽  
Wave Induced

Sandbank-lagoons are generally natural harbors for their good defense of wave, deep water near the coast and little source of sediments. Taking Bohe harbor locating on the sandbank-lagoon in South China as the example, water-sediment regime in the harbor block has been studied in this paper. It is shown that wave-induced long-shore current has a significant impact on the sediment movements in the planned harbor block and its back-silting is controlled by SW flow and wave power, and the training dike can trap sediment into the harbor block. And so in the harbor block planned around the west side of Bohe bay mouth not only can shelter the entrance of the lagoon and control wave-induced long-shore current, but also improve environment for back-silting.

Response of a Simple Tension Leg Platform Model to Wave Forces Calculated at Displaced Position

1984 ◽  
Vol 106 (4) ◽  
pp. 437-443 ◽  
Author(s):  
P. D. Spanos ◽  
V. K. Agarwal
Keyword(s):  
Structural Response ◽  
Offshore Structures ◽  
Wave Forces ◽  
Structural Members ◽  
Tension Leg Platform ◽  
Single Degree Of Freedom ◽  
Numerical Studies ◽  
Simple Tension ◽  
Stochastic Solution ◽  
Wave Induced

A simple single-degree-of-freedom model of a tension leg platform is used to assess the reliability of the common practice of calculating wave-induced forces at the undisplaced position of offshore structures. This assessment is conducted in conjunction with the Morison equation based modeling of the wave-induced forces on slender structural members. It is shown by numerically integrating the equation of motion that the calculation of wave forces on the displaced position of the structure introduces a steady offset component in the structural response. This is valid for either deterministically or stochastically described wave fields. Several parameter studies are conducted. Furthermore, reliable approximate analytical deterministic and stochastic solution techniques are developed which conform to and, in fact, predict the conclusions drawn from the results of the numerical studies.

The Equivalent Depth of Wave-Induced Scour Around Offshore Pipelines

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Mir Emad Mousavi ◽  
Abbas Yeganeh Bakhtiary ◽  
Nastaran Enshaei
Keyword(s):  
Deep Water ◽  
Wave Motion ◽  
Scour Depth ◽  
Offshore Pipelines ◽  
Equivalent Depth ◽  
Physical Experiments ◽  
Water Conditions ◽  
Installation Depth ◽  
New Equation ◽  
Wave Induced

Physical experiments have been conducted to study the scouring around a pipe over an erodible bed under wave motion. The results show that the depth of the wave-induced scour is reduced when the pipe is installed in a primary depth. It is also indicated that when the primary installation depth of the pipe, |e|, exceeds a specified depth, no scouring occurs underneath the pipe. This specific depth is called the equivalent depth of wave-induced scour, Se. The equivalent depth of wave-induced scour is estimated as a function of pipe diameter and the Keulegan–Carpenter number. With respect to the primary installation depth of the pipe, a new equation is suggested to predict the scour depth before installation of the pipe. And the scour width is predicted in two other new equations. The proposed equations are then simplified in the form of diagrams. The experiments cover small KC numbers (KC<6) that represent deep water conditions.

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