共查询到20条相似文献，搜索用时 15 毫秒
1.
T. C. S. Rendall C. B. Allen 《International journal for numerical methods in engineering》2009,78(10):1188-1208
Previous work by the authors has developed a universal interpolation scheme, using radial basis functions (RBFs), which results in a unified formulation for robust fluid–structure interpolation and high‐quality mesh motion. The method has several significant advantages. Primarily, all volume mesh, structural mesh, and flow‐solver‐type dependence is removed entirely, as all operations are performed on totally arbitrary point clouds of any form. Hence, all connectivity requirements are removed from both the coupling and mesh motion problems. Furthermore, only matrix‐vector multiplications are required during unsteady simulation because dependence relations are computed once prior to any simulation and then remain constant. This property means that the method is both perfectly parallel and totally independent from the flow‐solver. However, the full method is expensive, since the dependence matrix between two sets of points is N × N. The fluid–structure coupling behaviour can also be influenced by parameters used in the interpolation. To alleviate these difficulties a more efficient form of the RBF fluid–structure coupling is presented, which also greatly reduces the interpolation parameter influence. A pointwise form of the partition of unity approach is developed that localizes the interpolation, with results presented for static aeroelastic simulations of the Brite‐Euram multi‐disciplinary optimization wing using a very fine mesh containing 58 000 surface points. It is shown that a 58 × reduction in data size is achieved, and equally importantly the interpolation has a much smaller influence on final aeroelastic results. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
2.
Stefan Schoder Klaus Roppert Michael Weitz Clemens Junger Manfred Kaltenbacher 《International journal for numerical methods in engineering》2020,121(9):2051-2067
In low Mach number aeroacoustics, the known disparity of length scales makes it possible to apply well-suited simulation models using different meshes for flow and acoustics. The workflow of these hybrid methodologies include performing an unsteady flow simulation, computing the acoustic sources, and simulating the acoustic field. Therefore, hybrid methods seek for robust and flexible procedures, providing a conservative mesh to mesh interpolation of the sources while ensuring high computational efficiency. We propose a highly specialized radial basis function interpolation for the challenges during hybrid simulations. First, the computationally efficient local radial basis function interpolation in conjunction with a connectivity-based neighbor search technique is presented. Second, we discuss the computation of spatial derivatives based on radial basis functions. These derivatives are computed in a local-global approach, using a Gaussian kernel on local point stencils. Third, radial basis function interpolation and derivatives are used to compute complex aeroacoustic source terms. These ingredients are necessary to provide flexible source term calculations that robustly connect flow and acoustics. Finally, the capabilities of the presented approach are shown in a numerical experiment with a co-rotating vortex pair. 相似文献
3.
Shuvam Sen Guillaume De Nayer Michael Breuer 《International journal for numerical methods in engineering》2017,111(3):273-300
The present work introduces an efficient technique for the deformation of block‐structured grids occurring in simulations of fluid–structure interaction (FSI) problems relying on large‐eddy simulation (LES). The proposed hybrid approach combines the advantages of the inverse distance weighting (IDW) interpolation with the simplicity and low computational effort of transfinite interpolation (TFI), while preserving the mesh quality in boundary layers. It is an improvement over the state‐of‐the‐art currently in use. To reach this objective, in a first step, three elementary mesh deformation methods (TFI, IDW, and radial basis functions) are investigated based on several test cases of different complexities analyzing not only their capabilities but also their computational costs. That not only allows to point out the advantages of each method but also demonstrates their drawbacks. Based on these specific properties of the different methods, a hybrid methodology is suggested that splits the entire grid deformation into two steps: first, the movement of the block‐boundaries of the block‐structured grid and second, the deformation of each block of the grid. Both steps rely on different methodologies, which allows to work out the most appropriate method for each step leading to a reasonable compromise between the grid quality achieved and the computational effort required. Finally, a hybrid IDW‐TFI methodology is suggested that best fits to the specific requirements of coupled FSI‐LES applications. This hybrid procedure is then applied to a real‐life FSI‐LES case. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
4.
T. C. S. Rendall C. B. Allen 《International journal for numerical methods in engineering》2010,81(1):89-105
Radial basis functions are used to provide a solution to the problem of mesh motion for unsteady aerodynamic simulation. The method is independent of connectivity and produces high‐quality meshes, but is expensive for large meshes in its full form. Hence, the efficiency of the technique has been greatly improved here by reducing the number of surface points used to define deformations of the surface, and the minor error in position that this implies at other surface points is corrected with a simple decaying perturbation, thus splitting the method into a primary basis function method and a secondary local correction method. This means that the exact surface is retained, but the mesh motion is significantly faster, while splitting the motion into two stages allows both the methods to work on appropriate problems given their relative strengths. An example deformation for a 5×106 cell helicopter rotor mesh with an exaggerated cyclic pitch motion shows excellent mesh quality, thus validating a scheme that is also simple, robust and readily parallelized. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
5.
采用基于紧支距离基函数近似的配点型无网格方法对波在各向异性层状介质中的传播规律进行了数值模拟,得到了应力波的传播历程,并与冲击载荷作用下的有限元计算结果值进行了比较。该方法所得到的结果与有限元计算的结果吻合较好。说明该方法可以有效地模拟波在各向异性材料中的传播过程。 相似文献
6.
Z. Luo N. Zhang W. Gao H. Ma 《International journal for numerical methods in engineering》2012,90(3):369-389
This paper aims to propose a meshless Galerkin level set method for shape and topology optimization of continuum structures. To take advantage of the implicit free boundary representation scheme, the design boundary is represented as the zero level set of a scalar level set function, to flexibly handle complex shape fidelity and topology changes by maintaining concise and smooth interface. Compactly supported radial basis functions (CSRBFs) are used to parameterize the level set function and construct the shape functions for meshfree approximations based on a set of unstructured field nodes. The meshless Galerkin method with global weak form is used to implement the discretization of the state equations. This provides a pathway to unify the two different numerical stages in most conventional level set methods: (1) the propagation of discrete level set function on a set of Eulerian grid and (2) the approximation of discrete equations on a set of Lagrangian mesh. The original more difficult shape and topology optimization based on the level set equation is transformed into a relatively easier size optimization, to which many efficient optimization algorithms can be applied. The proposed level set method can describe the moving boundaries without remeshing for discontinuities. The motion of the free boundary is just a question of advancing the discrete level set function in time by solving the size optimization. Several benchmark examples are used to demonstrate the effectiveness of the proposed method. The numerical results show that the proposed method can simplify numerical process and avoid numerical difficulties involved in most conventional level set methods. It is straightforward to apply the proposed method to more advanced shape and topology optimization problems. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
7.
M. Cordero‐Gracia M. Gómez E. Valero 《International journal for numerical methods in engineering》2014,99(12):888-905
In loosely‐coupled aeroelastic computation, the aerodynamic and elastomechanical models are based on different grids and eventually a simplified structural model, like a shell or stick, is considered. CFD tools are applied over the aerodynamic grid, whereas CSM tools are over the structural one. The meshes are usually non‐conforming; thus, three‐dimensional and non‐intrusive interpolation procedures are necessary to transfer structural deformations to the aerodynamic surface grid and aerodynamic loads to the structure. For that purpose, an interpolator based on radial basis functions has been developed. This tool does not require grid connectivities and can be applied to any three‐dimensional data. We have developed two strategies to deal with two special cases of interest. The first is when the structure is represented by a beam model and there is not a proper structural mesh close to the aerodynamic surface. The second is when managing a full configuration aircraft and the problem has been split into some small blocks in such a way that there are aerodynamic nodes belonging to more than one block. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
8.
Joan Baiges Ramon Codina 《International journal for numerical methods in engineering》2010,81(12):1529-1557
In this paper we propose a method to solve Solid Mechanics and fluid–structure interaction problems using always a fixed background mesh for the spatial discretization. The main feature of the method is that it properly accounts for the advection of information as the domain boundary evolves. To achieve this, we use an Arbitrary Lagrangian–Eulerian (ALE) framework, the distinctive characteristic being that at each time step results are projected onto a fixed, background mesh. For solid mechanics problems subject to large strains, the fixed‐mesh (FM)‐ALE method avoids the element stretching found in fully Lagrangian approaches. For FSI problems, FM‐ALE allows for the use of a single background mesh to solve both the fluid and the structure. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
9.
Y. C. Hon Zongmin Wu 《International journal for numerical methods in engineering》2000,48(8):1187-1197
Based on the idea of quasi‐interpolation and radial basis functions approximation, a numerical method is developed to quasi‐interpolate the forcing term of differential equations by using radial basis functions. A highly accurate approximation for the solution can then be obtained by solving the corresponding fundamental equation and a small size system of equations related to the initial or boundary conditions. This overcomes the ill‐conditioning problem resulting from using the radial basis functions as a global interpolant. Error estimation is given for a particular second‐order stiff differential equation with boundary layer. The result of computations indicates that the method can be applied to solve very stiff problems. With the use of multiquadric, a special class of radial basis functions, it has been shown that a reasonable choice for the optimal shape parameter is obtained by taking the same value of the shape parameter as the perturbed parameter contained in the stiff equation. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
10.
In this work, we present a new monolithic strategy for solving fluid–structure interaction problems involving incompressible fluids, within the context of the finite element method. This strategy, similar to the continuum dynamics, conserves certain properties, and thus provides a rational basis for the design of the time‐stepping strategy; detailed proofs of the conservation of these properties are provided. The proposed algorithm works with displacement and velocity variables for the structure and fluid, respectively, and introduces no new variables to enforce velocity or traction continuity. Any existing structural dynamics algorithm can be used without change in the proposed method. Use of the exact tangent stiffness matrix ensures that the algorithm converges quadratically within each time step. An analytical solution is presented for one of the benchmark problems used in the literature, namely, the piston problem. A number of benchmark problems including problems involving free surfaces such as sloshing and the breaking dam problem are used to demonstrate the good performance of the proposed method. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
11.
Gaëtan Compère Jean‐François Remacle Johan Jansson Johan Hoffman 《International journal for numerical methods in engineering》2010,82(7):843-867
In this paper, we identify and propose solutions for several issues encountered when designing a mesh adaptation package, such as mesh‐to‐mesh projections and mesh database design, and we describe an algorithm to integrate a mesh adaptation procedure in a physics solver. The open‐source MAdLib package is presented as an example of such a mesh adaptation library. A new technique combining global node repositioning and mesh optimization in order to perform arbitrarily large deformations is also proposed. We then present several test cases to evaluate the performances of the proposed techniques and to show their applicability to fluid–structure interaction problems with arbitrarily large deformations. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
12.
Matteo Aletti Damiano Lombardi 《International journal for numerical methods in engineering》2017,111(6):581-600
This work investigates a model reduction method applied to coupled multi‐physics systems. The case in which a system of interest interacts with an external system is considered. An approximation of the Poincaré–Steklov operator is computed by simulating, in an offline phase, the external problem when the inputs are the Laplace–Beltrami eigenfunctions defined at the interface. In the online phase, only the reduced representation of the operator is needed to account for the influence of the external problem on the main system. An online basis enrichment is proposed in order to guarantee a precise reduced‐order computation. Several test cases are proposed on different fluid–structure couplings. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
13.
M. Zerroukat H. Power C. S. Chen 《International journal for numerical methods in engineering》1998,42(7):1263-1278
Simple, mesh/grid free, numerical schemes for the solution of heat transfer problems are developed and validated. Unlike the mesh or grid-based methods, these schemes use well-distributed quasi-random collocation points and approximate the solution using radial basis functions. The schemes work in a similar fashion as finite differences but with random points instead of a regular grid system. This allows the computation of problems with complex-shaped boundaries in higher dimensions with no extra difficulty. © 1998 John Wiley & Sons, Ltd. 相似文献
14.
XIAODONG WANG KLAUS-JÜRGEN BATHE 《International journal for numerical methods in engineering》1997,40(11):2001-2017
We present reliable finite element discretizations based on displacement/pressure interpolations for the analysis of acoustic fluid–structure interaction problems. The finite element interpolations are selected using the inf-sup condition, and emphasis is given to the fact that the boundary conditions must satisfy the mass and momentum conservation. We show that with our analysis procedure no spurious non-zero frequencies are encountered, as heretofore calculated with other displacement-based discretizations. © 1997 by John Wiley & Sons, Ltd. 相似文献
15.
Jos L. Ortiz Alan A. Barhorst Rush D. Robinett 《International journal for numerical methods in engineering》1998,41(3):409-433
Modelling the dynamics of a flexible multibody system coupled to a rigid container carrying a fluid with a free surface is addressed. The proposed methodology allows the analyst to implement all sort of non-linearities inherent in the dynamics of the structure. Potential flow with modified Rayleigh damping is used to model the fluid. Non-linear sloshing effects are considered and no simplifications are made on the field equations and boundary conditions. A set of first-order differential equations for the motion of both the structure and the fluid are presented. Emphasis is placed on the point that the motion of the flexible multibody system is not prescribed but is found as part of the solution procedure. Some improvements are presented with respect to a previous introductory work by the authors. Detailed derivations and two numerical examples are presented: a flexible column supporting a rigid water tank (with a comparison using an approximate method) and a double flexible-link pendulum coupled to a rigid container. © 1998 This paper was produced under the auspices of the U.S. Government and it is therefore not subjected to copyright in the U.S. 相似文献
16.
Jing Li Charbel Farhat Philip Avery Radek Tezaur 《International journal for numerical methods in engineering》2012,89(4):418-437
The dual‐primal finite element tearing and interconnecting method (FETI‐DP) is extended to systems of linear equations arising from a finite element discretization for a class of fluid–structure interaction problems in the frequency domain. A preconditioned generalized minimal residual method is used to solve the linear equations for the Lagrange multipliers introduced on the subdomain boundaries to enforce continuity of the solution. The coupling between the fluid and the structure on the fluid–structure interface requires an appropriate choice of coarse level degrees of freedom in the FETI‐DP algorithm to achieve fast convergence. Several choices are proposed and tested by numerical experiments on three‐dimensional fluid–structure interaction problems in the mid‐frequency regime that demonstrate the greatly improved performance of the proposed algorithm over the standard FETI‐DP method. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
17.
Cornel Marius Murea Soyibou Sy 《International journal for numerical methods in engineering》2017,109(8):1067-1084
We propose a numerical method for a fluid–structure interaction problem. The material of the structure is homogeneous, isotropic, and it can be described by the compressible neo‐Hookean constitutive equation, while the fluid is governed by the Navier–Stokes equations. Our study does not use turbulence model. Updated Lagrangian method is used for the structure and fluid equations are written in Arbitrary Lagrangian–Eulerian coordinates. One global moving mesh is employed for the fluid–structure domain, where the fluid–structure interface is an ‘interior boundary’ of the global mesh. At each time step, we solve a monolithic system of unknown velocity and pressure defined on the global mesh. The continuity of velocity at the interface is automatically satisfied, while the continuity of stress does not appear explicitly in the monolithic fluid–structure system. This method is very fast because at each time step, we solve only one linear system. This linear system was obtained by the linearization of the structure around the previous position in the updated Lagrangian formulation and by the employment of a linear convection term for the fluid. Numerical results are presented. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
18.
M. Cremonesi A. Frangi U. Perego 《International journal for numerical methods in engineering》2010,84(5):610-630
A Lagrangian finite element method for the analysis of incompressible Newtonian fluid flows, based on a continuous re‐triangulation of the domain in the spirit of the so‐called Particle Finite Element Method, is here revisited and applied to the analysis of the fluid phase in fluid–structure interaction problems. A new approach for the tracking of the interfaces between fluids and structures is proposed. Special attention is devoted to the mass conservation problem. It is shown that, despite its Lagrangian nature, the proposed combined finite element‐particle method is well suited for large deformation fluid–structure interaction problems with evolving free surfaces and breaking waves. The method is validated against the available analytical and numerical benchmarks. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
19.
F. Toth M. Kaltenbacher 《International journal for numerical methods in engineering》2016,107(11):947-969
Incompressible free‐surface flow is a common assumption for the modelling of water waves. Connected with the aim to develop very large floating platforms, air chamber supported floating structures have attracted considerable research interest in the past. Such structures are carried by air entrapped in chambers formed by stiff, vertical walls. In order to model these types of structures, the interactions between surface gravity waves and compressible air must be taken into account. If the payload requirements for air chamber supported structures are low enough, the air chambers may be formed by flexible membrane cylinders. In such systems, pressure variations can lead to considerable changes in chamber volume. Therefore, the flexibility of the bounding structures must be taken into account. We present a modelling strategy to tackle the fully coupled problem of compressible gas in a flexible chamber and incompressible free‐surface flow in an unbounded domain. The governing equations and boundary conditions are described and solved by the finite element method. A perfectly matched layer is used to obtain a solution for an unbounded domain. Finally, the numerical implementation is validated by various test cases. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
20.
David J. Chappell Paul J. Harris David Henwood Roma Chakrabarti 《International journal for numerical methods in engineering》2008,75(3):275-290
Coupled finite and boundary element methods for solving transient fluid–structure interaction problems are developed. The finite element method is used to model the radiating structure, and the boundary element method (BEM) is used to determine the resulting acoustic field. The well‐known stability problems of time domain BEMs are avoided by using a Burton–Miller‐type integral equation. The stability, accuracy and efficiency of two alternative solution methods are compared using an exact solution for the case of a thin spherical elastic shell. The convergence properties of the preferred solution method are then investigated more thoroughly. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献