Developing Vertical Column Induced Gas Flotation for Floating Platforms Using Computational Fluid Dynamics

2004 ◽  
Author(s):  
Chang-Ming Lee ◽  
Ted Frankiewicz
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Vertical Column ◽  
Floating Platforms

CFD Simulation for Vortex Induced Motions of a Multi-Column Floating Platform

2013 ◽  
Author(s):  
Jaime Hui Choo Tan ◽  
Allan Magee ◽  
Jang Whan Kim ◽  
Yih Jeng Teng ◽  
NorBahrain Ahmad Zukni
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Research Effort ◽  
Model Tests ◽  
Floating Platform ◽  
Time Step ◽  
Time Step Size ◽  
Standard Design ◽  
Computational Fluid Dynamics Cfd ◽  
Floating Platforms

The potential of vortex induced motion (VIM) in multi-column floating platforms such as semi-submersibles and tension leg platforms (TLPs) is well-acknowledged although the industry guidelines for design for VIM are not comprehensive and more research effort is required. Significant VIM in multi-column floating platforms will affect the fatigue life of the steel catenary risers and must be quantified and sometimes reduced. Industry-standard design tools used for drag estimation based on model tests of fixed structures may not accurately reflect the effects of drag augmentation due to VIM. Model tests and Computational Fluid Dynamics (CFD) analysis are feasible methods to investigate VIM, with the latter being more resource-efficient, provided sufficient benchmarking has been carried out to ensure reliable results. Subsequent to the model tests and preliminary Computational Fluid Dynamics (CFD) simulations done for a multi-column floating platform [1, 2], further CFD analyses for the VIM of the floating platform have been carried out using improved simulation techniques with a commercial software. Good agreement between model test results and CFD calculations for VIM of a multi-column floating platform is observed. Sensitivity of CFD results to the modeling assumptions such as mesh size and density, time-step size and different turbulence models is presented.

Computational Fluid Dynamics Reproduction of Nonlinear Loads on a Vertical Column During Extreme Irregular Wave Events

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Erin E. Bachynski ◽  
Csaba Pákozdi ◽  
Anders Östman ◽  
Carl Trygve Stansberg
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Vertical Cylinder ◽  
Test Case ◽  
Wave Loads ◽  
Reconstruction Procedure ◽  
Vertical Column ◽  
Irregular Wave ◽  
Wave Maker ◽  
The Waves

Recently, a method for numerical reproduction of measured irregular wave events has been developed. The measured motion of the wave maker flaps defines the wave kinematics at the boundary of the numerical simulation in order to generate the waves. When such data are not available, the control signal of the wave maker can, instead, be generated from a given free surface elevation following the same procedure as in model tests. This procedure is applied to a model test case with extreme irregular wave events and resulting nonlinear global wave loads on a vertical cylinder, focusing on higher-order ringing excitation. The purpose of the investigation is twofold: (1) to validate the wave reconstruction procedure and (2) to validate the resulting computational fluid dynamics (CFD) ringing loads with the given waves. In order to better understand the frequency content in the CFD-generated loads, wavelet analysis as well as the response of a single degree-of-freedom (SDOF) oscillator is examined and compared with the corresponding results for the third-order wave forcing based on the MacCamy–Fuchs (MF) and Faltinsen, Newman, Vinje (FNV) formulations. The results show generally good agreement between CFD and experiment both in the waves and in the loads; discrepancies found in the loads mainly originate from corresponding uncertainties in the wave reconstruction. Wave breaking may be one source of uncertainty. The MF + FNV formulation showed reasonable prediction of the maximum responses of an SDOF oscillator, but could not capture the loads well at all of the important frequencies.

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