The Experts below are selected from a list of 490467 Experts worldwide ranked by ideXlab platform
Yun Zhang - One of the best experts on this subject based on the ideXlab platform.
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Coupled Analysis of floating structures with a new mooring system
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: Chunyan Ji, Minglu Chen, Yun ZhangAbstract:As the exploitation of hydrocarbon reserves moves towards deeper waters, the floating structures are becoming more and more popular, and the catenary and taut mooring systems are two widespread mooring systems which are used for these floating structures. However, both of them have their inherent drawbacks. The aim of the present work is to develop and validate a new mooring system which will overcome these shortcomings. To this end, the motion performance of a semi-submersible platform is simulated by employing a full time domain Coupled Analysis method. It is shown that the new mooring system yields very good motion performance when benchmarked against the taut mooring system, and the reasons for this improved performance are discussed. Also, the new mooring system is compatible with the characteristic of catenary mooring system, which eliminates the requirement of anti-uplift capacity of the anchors. The second aim of this paper is to explore the proper water depth in employing this new mooring system. For this purpose, several typical water depths are simulated. It is found that the new mooring system works well both in deep water and ultra-deep water. But, as the water depth becomes deeper, the advantages of the new mooring system are reduced.Copyright © 2011 by ASME
Rajeev K Jaiman - One of the best experts on this subject based on the ideXlab platform.
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a hybrid variational allen cahn ale scheme for the Coupled Analysis of two phase fluid structure interaction
International Journal for Numerical Methods in Engineering, 2019Co-Authors: Vaibhav Joshi, Rajeev K JaimanAbstract:We present a novel partitioned iterative formulation for modeling of fluid-structure interaction in two-phase flows. The variational formulation consists of a stable and robust integration of three blocks of differential equations, viz., incompressible viscous fluid, a rigid or flexible structure and two-phase indicator field. The fluid-fluid interface between the two phases, which may have high density and viscosity ratios, is evolved by solving the conservative phase-field Allen-Cahn equation in the arbitrary Lagrangian-Eulerian coordinates. While the Navier-Stokes equations are solved by a stabilized Petrov-Galerkin method, the conservative Allen-Chan phase-field equation is discretized by the positivity preserving variational scheme. Fully deCoupled implicit solvers for the two-phase fluid and the structure are integrated by the nonlinear iterative force correction in a staggered partitioned manner. We assess the accuracy and stability of the new phase-field/ALE variational formulation for two- and three-dimensional problems involving the dynamical interaction of rigid bodies with free-surface. We consider the decay test problems of increasing complexity, namely free translational heave decay of a circular cylinder and free rotation of a rectangular barge. Through numerical experiments, we show that the proposed formulation is stable and robust for high density ratios across fluid-fluid interface and for low structure-to-fluid mass ratio with strong added-mass effects. Using three-dimensional unstructured meshes, we demonstrate the second-order temporal accuracy of the Coupled phase-field/ALE method. Finally, we demonstrate the three-dimensional phase-field FSI formulation for a practical problem of internal two-phase flow in a flexible circular pipe subjected to vortex-induced vibrations due to external fluid flow.
Fusao Oka - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation of progressive failure in cut slope of soft rock using a soil water Coupled finite element Analysis
Soils and Foundations, 2003Co-Authors: Feng Zhang, Atsushi Yashima, Hitomi Osaki, Toshihisa Adachi, Fusao OkaAbstract:ABSTRACT In the present paper, based onan elastoplastic model with strain hardening and strain softening, a soil-water Coupled finite element Analysis is conducted to investigate the progressive failure of a cut slope in a model ground. In order to verify the validity of the analyses related to the strain-softening behavior, numerical analyses are firstly conducted for plane-strain compression in different meshes and loading steps under complete drained condition. It is confirmed by the analyses that the Analysis conducted in this paper has a small dependency on the mesh size. Then, the mechanical behaviours of a cut slope, such as the change of excessive pore-water pressure, the redistribution of stress in ground due to strain softening, the propagation of shear band and the progressive failure are discussed in detail by the soil-water Coupled finite element Analysis. It is found that a soil-water Coupled Analysis based on an elastoplastic model can describe the time dependent behavior of soft rock in boundary-value problems. It is also found that a soil-water Coupled Analysis based on a strain-softening model can simulate the progressive failure of a cut slope.
Chunyan Ji - One of the best experts on this subject based on the ideXlab platform.
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Coupled Analysis of floating structures with a new mooring system
ASME 2011 30th International Conference on Ocean Offshore and Arctic Engineering, 2011Co-Authors: Chunyan Ji, Minglu Chen, Yun ZhangAbstract:As the exploitation of hydrocarbon reserves moves towards deeper waters, the floating structures are becoming more and more popular, and the catenary and taut mooring systems are two widespread mooring systems which are used for these floating structures. However, both of them have their inherent drawbacks. The aim of the present work is to develop and validate a new mooring system which will overcome these shortcomings. To this end, the motion performance of a semi-submersible platform is simulated by employing a full time domain Coupled Analysis method. It is shown that the new mooring system yields very good motion performance when benchmarked against the taut mooring system, and the reasons for this improved performance are discussed. Also, the new mooring system is compatible with the characteristic of catenary mooring system, which eliminates the requirement of anti-uplift capacity of the anchors. The second aim of this paper is to explore the proper water depth in employing this new mooring system. For this purpose, several typical water depths are simulated. It is found that the new mooring system works well both in deep water and ultra-deep water. But, as the water depth becomes deeper, the advantages of the new mooring system are reduced.Copyright © 2011 by ASME
Vaibhav Joshi - One of the best experts on this subject based on the ideXlab platform.
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a hybrid variational allen cahn ale scheme for the Coupled Analysis of two phase fluid structure interaction
International Journal for Numerical Methods in Engineering, 2019Co-Authors: Vaibhav Joshi, Rajeev K JaimanAbstract:We present a novel partitioned iterative formulation for modeling of fluid-structure interaction in two-phase flows. The variational formulation consists of a stable and robust integration of three blocks of differential equations, viz., incompressible viscous fluid, a rigid or flexible structure and two-phase indicator field. The fluid-fluid interface between the two phases, which may have high density and viscosity ratios, is evolved by solving the conservative phase-field Allen-Cahn equation in the arbitrary Lagrangian-Eulerian coordinates. While the Navier-Stokes equations are solved by a stabilized Petrov-Galerkin method, the conservative Allen-Chan phase-field equation is discretized by the positivity preserving variational scheme. Fully deCoupled implicit solvers for the two-phase fluid and the structure are integrated by the nonlinear iterative force correction in a staggered partitioned manner. We assess the accuracy and stability of the new phase-field/ALE variational formulation for two- and three-dimensional problems involving the dynamical interaction of rigid bodies with free-surface. We consider the decay test problems of increasing complexity, namely free translational heave decay of a circular cylinder and free rotation of a rectangular barge. Through numerical experiments, we show that the proposed formulation is stable and robust for high density ratios across fluid-fluid interface and for low structure-to-fluid mass ratio with strong added-mass effects. Using three-dimensional unstructured meshes, we demonstrate the second-order temporal accuracy of the Coupled phase-field/ALE method. Finally, we demonstrate the three-dimensional phase-field FSI formulation for a practical problem of internal two-phase flow in a flexible circular pipe subjected to vortex-induced vibrations due to external fluid flow.
