Interaction of vortex shedding processes on flow over a deep-draft semi-submersible

Liang, Yibo; Tao, Longbin

doi:10.1016/j.oceaneng.2017.06.056

Cited by 14 publications

(10 citation statements)

References 26 publications

(33 reference statements)

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“…It is noted that the Froude number is quite small (Fr < 0.2, Fr = U/√gD, where U is the current velocity, g is the acceleration of gravity and D is the projected width of the column) in all simulations of the present investigation. As observed in the physical model tests [22], the free surface effects were rather limited and can be ignored. Therefore, only the submerged geometry is considered, and the geometry of the structure above the waterline will not affect the simulation results.…”

Section: Computational Domainmentioning

confidence: 84%

“…Three different corner shapes (sharp, chamfered and rounded) of a typical deep-draft semi-submersible under 45 degree flow incidence have been numerically investigated after present and previous rigorous validations [21][22][23] against the experimental data. The hydrodynamic loads on different members of the structure, such as four columns and pontoons, are compared in order to quantify the corner shape effects.…”

Section: Results and Analysismentioning

confidence: 99%

“…The details of mesh and time step sensitivity studies have been presented in the previous studies [22,23]. In the present study, the results for all cases were obtained by averaging after more than fifty vortex shedding cycles.…”

Section: Sensitivity and Validation Studymentioning

confidence: 99%

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Hydrodynamics Around a Deep-Draft Semi-Submersible With Various Corner Shapes

Liang

Tao

2018

Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics

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A numerical study on flow over a stationary deep-draft semi-submersible (DDS) with various corner shapes was carried out to investigate the corner shape effects on the overall hydrodynamics. Three models based on a typical DDS design with different corner shapes were numerically investigated under 45° incidence. The present numerical model has been validated by an experimental test carried out in a circulating water channel. It is demonstrated that, as the corner shape design changed, the hydrodynamic characteristics alter drastically. In addition, the flow patterns were examined to reveal some insights of the fluid physics due to the changing of different corner shape designs. The detailed numerical results from the geometric study will provide a good guidance for future practical designs.

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Section: Computational Domainmentioning

confidence: 84%

Section: Results and Analysismentioning

confidence: 99%

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Hydrodynamics Around a Deep-Draft Semi-Submersible With Various Corner Shapes

Liang

Tao

2018

Volume 9: Offshore Geotechnics; Honoring Symposium for Professor Bernard Molin on Marine and Offshore Hydrodynamics

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“…There are few papers contributing to the examination of the physics of FIV on a multi finite length column structure. Therefore, the second contribution of the present study is to provide a comprehensive numerical study to examine the mechanism of FIV on a multi finite length column structure based on our well-validated numerical model 13,14 .…”

Section: Please Cite This Article As Doi:101063/15131325mentioning

confidence: 99%

Energy transformation on flow-induced motions of multiple cylindrical structures with various corner shapes

Tao

2020

Physics of Fluids

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A comprehensive numerical study on flow-induced motions (FIM) of a deepdraft semi-submersible (DDS), a typical multiple cylindrical structure in offshore engineering was carried out to investigate the energy transformation of the vortex shedding process. In addition, the corner shape effect on the flow characteristics, the hydrodynamic forces and the FIM responses are presented for a multiple cylindrical structure with various corner shapes (sharp, rounded and chamfered) under 45° current incidence. Different energy transformations, hydrodynamic characteristics and FIM responses were observed due to the slight variation of the corner shape. The galloping at 45° incidence for a square-section shape column was observed when the corner shape modified as a chamfered corner. A "re-attached vortex shedding" phenomenon is

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“…This technique is defined as an error percentage, providing a confidence bound in which the numerical solution will likely to be. Several authors used the mentioned GCI in computer fluid dynamics (Jin and Shaw, 2010;Liang and Tao, 2017;Ndebele and Skews, 2019). However, it is less mentioned in discrete methods (Kwaśniewski, 2013;Schwer, 2008), with no sources found for shock waves produced by explosive detonation.…”

Section: Introductionmentioning

confidence: 99%

Application of grid convergence index to shock wave validated with LS-DYNA and ProsAir

et al. 2020

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The discretization error is not always calculated, even though it is essential for the studies of computational solid mechanics. However, it is well known that an error committed by the mesh used can be as large as the measured variable, which greatly invalidates the results obtained. The grid convergence index (GCI) method makes possible to determine on a solid basis, the order of convergence and the asymptotic solution. This method seems to be a suitable estimator despite further research is needed in the context of blast situations and finite element (FE) calculations. For this purpose, field trials were performed consisting in the detonation of a spherical hanging load of homemade explosive. The pressure generated by the shock wave was measured in different positions at two distances. With these data, a TNT equivalent has been obtained and used to calculate the shock propagation with the solvers LS-DYNA and ProsAir. This work aims to verify the GCI method by comparing its results with field data along with the simulations carried out. The comparison also seeks to validate the methodology used to obtain the TNT equivalent.This research shows that the GCI gives good results for both solvers despite the complexity of the physical problem. Besides, LS-DYNA displays better correlation with the experimental data than the ProsAir results, with an error of less than 10% in all values. RESUMENLa estimación del error de discretización no siempre se calcula, aunque es algo fundamental para el estudio de la mecánica computacional de los sólidos. Sin embargo, es bien sabido que el error cometido por la malla utilizada puede ser del mismo orden que la variable medida, lo que llega a invalidar los resultados obtenidos. El método del ındice de convergencia de la malla (GCI) permite determinar sobre una base sólida el orden de convergencia y la solución asintótica, por lo que parece ser un buen estimador, a pesar de que es necesario seguir investigando en el contexto de las situaciones de ondas de choque (explosivos) y de los cálculos de elementos finitos (FE). Para este fin, se realizaron pruebas de campo consistentes en la detonación de una carga esférica colgada de explosivo casero. La presión generada por la onda de choque se midió en diferentes posiciones a dos distancias. Con estos datos, se obtuvo un equivalente de TNT que se utilizó para calcular la propagación del choque con los programas LS-DYNA y ProsAir. Este trabajo pretende verificar el método GCI comparando sus resultados con los datos de campo junto con las simulaciones realizadas. También, la comparación busca validar la metodologıa empleada para la obtención del equivalente TNT.La investigación muestra que el GCI da buenos resultados para ambos programas a pesar de la complejidad del problema fısico. Además, el LS-DYNA produce una mejor correlación con los datos experimentales que los aportados por el ProsAir, con todos los valores por debajo del 10 % de error.Palabras clave: ındice de convergencia de malla (GCI), equivalente de TNT, LS-DYNA, ProsAir.How to ...

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Interaction of vortex shedding processes on flow over a deep-draft semi-submersible

Cited by 14 publications

References 26 publications

Hydrodynamics Around a Deep-Draft Semi-Submersible With Various Corner Shapes

Hydrodynamics Around a Deep-Draft Semi-Submersible With Various Corner Shapes

Energy transformation on flow-induced motions of multiple cylindrical structures with various corner shapes

Application of grid convergence index to shock wave validated with LS-DYNA and ProsAir

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