A semi-implicit algorithm of the partitioned method is newly proposed for fluid-structure interaction using the finite element method. In particular, an incompressible fluid flow is solved by a splitting method, and t...
详细信息
A semi-implicit algorithm of the partitioned method is newly proposed for fluid-structure interaction using the finite element method. In particular, an incompressible fluid flow is solved by a splitting method, and the solid domain of a reference configuration is solved by a total Lagrangian approach. While the viscous traction of the fluid flow is explicitly estimated in a coupling algorithm, the pressure traction from the fluid flow is implicitly coupled with the solid motion through iterative computations separately performed on the fluid and then the solid domain. By employing a weak formulation of the pressure Poisson equation based on a flux (fluid velocity) boundary condition, solid motion is successfully coupled with the pressure equation during the iterative computation. The proposed method has been found to be more efficient compared with not only a fully-implicit scheme of the partitioned method, but also a monolithic formulation in terms of CPU time and memory usage. Lastly, the parallel implementation of the proposed method is very attractive due to the fluid-solid coupling through a simple pressure Poisson equation.
The phase field method has been widely adopted in brittle fracture analysis for its ability to handle complex crack topology. This paper presents a novel efficient and robust phase field algorithm for quasi-static bri...
详细信息
The phase field method has been widely adopted in brittle fracture analysis for its ability to handle complex crack topology. This paper presents a novel efficient and robust phase field algorithm for quasi-static brittle fracture analysis. This algorithm overcomes two major issues that affect significantly the numerical cost of the method: the treatment of discontinuous crack propagation and the inequality constraint associated with the irreversibility of the damage evolution. To handle discontinuous crack propagation, a semi-implicit scheme, which combines the usual explicit and implicit schemes, is proposed. Different from explicit schemes that require small time steps and purely implicit schemes that lose immediately efficiency when encountering discontinuous propagation, the proposed method can alleviate the steps constraint while keeping a good robustness with discontinuous cracking. Concerning the irreversibility constraint, this work proposes a practical and easy-to-implement method. It is shown that this method is extremely efficient and robust without any supplementary numerical coefficient. The efficiency of the method is demonstrated by means of representative numerical examples. (C) 2020 Elsevier B.V. All rights reserved.
Supplemental viscous damping devices are generally envisioned to be connected in parallel to the inelastic parent structure or hysteretic damping devices. This gives rise to higher base shear, and often greater ductil...
详细信息
Supplemental viscous damping devices are generally envisioned to be connected in parallel to the inelastic parent structure or hysteretic damping devices. This gives rise to higher base shear, and often greater ductility demand of the hysteretic system. The series connection of the viscous and hysteretic system (the inelastic structure or a damper) is an alternative approach. In this paper, comparisons between the series and parallel connections of the hysteretic system and viscous dampers are done through response spectra analyses of single degree of freedom structures. Ductility demand of the hysteretic system and the total base shear are chosen as the response quantities. For the series model, a semi-implicit solution scheme for classical Maxwell model is modified to include the inelasticity of the time-independent hysteretic spring. It is observed that the series connection of the 2 dampers gives lower base shear than does the parallel connection. For long-period and low-damping structures, the ductility demand of the hysteretic system in series connection is higher than that in parallel connection. Increasing the viscous damping in series connection reduces the ductility demand substantially, lower than that obtained in parallel connection. Practical methods for implementing the series and parallel connections, in line with roof isolation, are also suggested.
The MPS (Moving Particle semi-implicit) method has been proven useful in computation free-surface hydrodynamic flows. Despite its applicability, one of its drawbacks in practical application is the high computational ...
详细信息
The MPS (Moving Particle semi-implicit) method has been proven useful in computation free-surface hydrodynamic flows. Despite its applicability, one of its drawbacks in practical application is the high computational load. On the other hand, Graphics Processing Unit (GPU), which was originally developed for acceleration of computer graphics, now provides unprecedented capability for scientific computations. The main objective of this study is to develop a GPU-accelerated MPS code using CUDA (Compute Unified Device Architecture) language. Several techniques have been shown to optimize calculations in CUDA. In order to promote the acceleration by CPU, particular attentions are given to both the search of neighboring particles and the iterative solution of simultaneous linear equations in the Poisson Pressure Equation. In this paper, 2-dimensional calculations of elliptical drop evolution and dam break flow have been carried out by the GPU-accelerated MPS method, and the accuracy and performance of GPU-based code are investigated by comparing the results with those by CPU. It is shown that results of GPU-based calculations can be obtained much faster with the same reliability as the CPU-based ones. (C) 2011 Elsevier Ltd. All rights reserved.
This paper presents two semi-implicit algorithms based on splitting methodology for rigid body rotational dynamics. The first algorithm is a variation of partitioned Runge-Kutta (PRK) methodology that can be formulate...
详细信息
This paper presents two semi-implicit algorithms based on splitting methodology for rigid body rotational dynamics. The first algorithm is a variation of partitioned Runge-Kutta (PRK) methodology that can be formulated as a splitting method. The second algorithm is akin to a multiple time stepping scheme and is based on modified Crouch-Grossman (MCG) methodology, which can also be expressed as a splitting algorithm. These algorithms are second-order accurate and time-reversible;however, they are not Poisson integrators, i.e. non-symplectic. These algorithms conserve some of the first integrals of motion, but some others are not conserved;however, the fluctuations in these invariants are bounded over exponentially long time intervals. These algorithms exhibit excellent long-term behaviour because of their reversibility property and their (approximate) Poisson structure preserving property. The numerical results indicate that the proposed algorithms exhibit superior performance compared to some of the currently well known algorithms such as the Simo-Wong algorithm, Newmark algorithm, discrete Moser-Veselov algorithm, Lewis-Simo algorithm, and the LIEMID[EA] algorithm. Copyright (c) 2006 John Wiley & Sons, Ltd.
暂无评论