Статті в журналах: "Partitioned coupling method"

1

Akbay, Muzaffer, Nicholas Nobles, Victor Zordan, and Tamar Shinar. "An extended partitioned method for conservative solid-fluid coupling." ACM Transactions on Graphics 37, no. 4 (August 10, 2018): 1–12. http://dx.doi.org/10.1145/3197517.3201345.

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2

Yusa, Yasunori, and Shinobu Yoshimura. "Elastic-Plastic Fracture Analysis of Structure Using Partitioned Coupling Method." Proceedings of The Computational Mechanics Conference 2014.27 (2014): 466–67. http://dx.doi.org/10.1299/jsmecmd.2014.27.466.

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3

Schmidt, Patrick, Alexander Jaust, Holger Steeb, and Miriam Schulte. "Simulation of flow in deformable fractures using a quasi-Newton based partitioned coupling approach." Computational Geosciences 26, no. 2 (January 20, 2022): 381–400. http://dx.doi.org/10.1007/s10596-021-10120-8.

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AbstractWe introduce a partitioned coupling approach for iterative coupling of flow processes in deformable fractures embedded in a poro-elastic medium that is enhanced by interface quasi-Newton (IQN) methods. In this scope, a unique computational decomposition into a fracture flow and a poro-elastic domain is developed, where communication and numerical coupling of the individual solvers are realized by consulting the open-source library preCICE. The underlying physical problem is introduced by a brief derivation of the governing equations and interface conditions of fracture flow and poro-elastic domain followed by a detailed discussion of the partitioned coupling scheme. We evaluate the proposed implementation and undertake a convergence study to compare a classical interface quasi-Newton inverse least-squares (IQN-ILS) with the more advanced interface quasi-Newton inverse multi-vector Jacobian (IQN-IMVJ) method. These coupling approaches are verified for an academic test case before the generality of the proposed strategy is demonstrated by simulations of two complex fracture networks. In contrast to the development of specific solvers, we promote the simplicity and computational efficiency of the proposed partitioned coupling approach using preCICE and FEniCS for parallel computations of hydro-mechanical processes in complex, three-dimensional fracture networks.

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4

Lim, W. Z., and R. Y. Xiao. "Fluid—Structure Interaction Analysis of Flexible Plate with Partitioned Coupling Method." China Ocean Engineering 33, no. 6 (December 2019): 713–22. http://dx.doi.org/10.1007/s13344-019-0069-6.

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5

Ramegowda, Prakasha Chigahalli, Daisuke Ishihara, Tomoya Niho, and Tomoyoshi Horie. "Performance Evaluation of Numerical Finite Element Coupled Algorithms for Structure–Electric Interaction Analysis of MEMS Piezoelectric Actuator." International Journal of Computational Methods 16, no. 07 (July 26, 2019): 1850106. http://dx.doi.org/10.1142/s0219876218501062.

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This work presents multiphysics numerical analysis of piezoelectric actuators realized using the finite element method (FEM) and their performances to analyze the structure-electric interaction in three-dimensional (3D) piezoelectric continua. Here, we choose the piezoelectric bimorph actuator without the metal shim and with the metal shim as low-frequency problems and a surface acoustic wave device as a high-frequency problem. More attention is given to low-frequency problems because in our application micro air vehicle’s wings are actuated by piezoelectric bimorph actuators at low frequency. We employed the Newmark’s time integration and the central difference time integration to study the dynamic response of piezoelectric actuators. Monolithic coupling, noniterative partitioned coupling and partitioned iterative coupling schemes are presented. In partitioned iterative coupling schemes, the block Jacobi and the block Gauss–Seidel methods are employed. Resonance characteristics are very important in micro-electro-mechanical system (MEMS) applications. Therefore, using our proposed coupled algorithms, the resonance characteristics of bimorph actuator is analyzed. Comparison of the accuracy and computational efficiency of the proposed numerical finite element coupled algorithms have been carried out for 3D structure–electric interaction problems of a piezoelectric actuator. The numerical results obtained by the proposed algorithms are in good agreement with the theoretical solutions.

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6

MITSUME, N., S. YOSHIMURA, K. MUROTANI, and T. YAMADA. "MPS–FEM PARTITIONED COUPLING APPROACH FOR FLUID–STRUCTURE INTERACTION WITH FREE SURFACE FLOW." International Journal of Computational Methods 11, no. 04 (August 2014): 1350101. http://dx.doi.org/10.1142/s0219876213501016.

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Fluid–structure interaction analysis involving free surface flow has been investigated using mesh-based methods or mesh-free particle methods. While mesh-based methods have several problems in dealing with the fragmentation of geometry and moving interfaces and with the instability of nonlinear advective terms, mesh-free particle methods can deal with free surface and moving boundary relatively easily. In structural analyses, the finite element method, which is a mesh-based method, has been investigated extensively and can accurately deal with not only elastic problems but also plastic and fracture problems. Thus, the present study proposes a partitioned coupling strategy for fluid–structure interaction problems involving free surfaces and moving boundaries that calculates the fluid domain using the moving particle simulation method and the structure domain using the finite element method. As the first step, we apply a conventional serial staggered algorithm as a weak coupling scheme. In addition, for the verification of the proposed method, the problem of a breaking dam on an elastic wall is calculated, and the results are compared with the results obtained by other methods.

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7

Li, Yuting, Minghao Liu, Yinxing Li, and Peng You. "Research on Population Spatialization Method Based on PMST-SRCNN." E3S Web of Conferences 165 (2020): 03019. http://dx.doi.org/10.1051/e3sconf/202016503019.

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How to improve the accuracy of population spatialization by using downscaling technology has always been a difficult issue in academic research. The population spatialization model constructed from the global or local perspective alone has its own limitations that cannot capture the local and global characteristics of the population distribution. Based on the counties of Chongqing municipality in 2010, this paper uses the two steps of “removing-rough” rasterizationof partitioned multivariate statistical regression and the “getting-accuracy” of super-resolution convolutional neural network to construct a coupling model of population spatialization to complete global and local Feature learning and compare and analyze with other four schemes. The results show that the mean square error and root mean square error of the coupled model of partitioned multivariate statistical regression and super-resolution convolutional neural network are the lowest, especially in densely populated areas. Studies have shown that although super-resolution convolutional neural network has a good ability to downscale learning, it still does not reflect the heterogeneity of population spatial patterns well, and the coupling of multilevel global feature learning models and super-resolution convolutional neural network models can make up for this to a certain extent.

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8

He, Tao, Dai Zhou, Zhaolong Han, Jiahuang Tu, and Jin Ma. "Partitioned subiterative coupling schemes for aeroelasticity using combined interface boundary condition method." International Journal of Computational Fluid Dynamics 28, no. 6-10 (June 27, 2014): 272–300. http://dx.doi.org/10.1080/10618562.2014.927057.

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9

Delgado, Carlos, Javier Moreno, and Felipe Cátedra. "Application of a Sparsity Pattern and Region Clustering for Near Field Sparse Approximate Inverse Preconditioners in Method of Moments Simulations." International Journal of Antennas and Propagation 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/9845050.

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This document presents a technique for the generation of Sparse Inverse Preconditioners based on the near field coupling matrices of Method of Moments simulations where the geometry has been partitioned in terms of regions. A distance parameter is used to determine the sparsity pattern of the preconditioner. The rows of the preconditioner are computed in groups at a time, according to the number of unknowns contained in each region of the geometry. Two filtering thresholds allow considering only the coupling terms with a significant weight for a faster generation of the preconditioner and storing only the most significant preconditioner coefficients in order to decrease the memory required. The generation of the preconditioner involves the computation of as many independent linear least square problems as the number of regions in which the geometry is partitioned, resulting in very good scalability properties regarding its parallelization.

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10

Li, Hui, Hongwu Zhang, Yonggang Zheng, Hongfei Ye, and Mengkai Lu. "An Implicit Coupling Finite Element and Peridynamic Method for Dynamic Problems of Solid Mechanics with Crack Propagation." International Journal of Applied Mechanics 10, no. 04 (May 2018): 1850037. http://dx.doi.org/10.1142/s1758825118500370.

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An implicit coupling finite element and peridynamic (PD) method is developed in this paper for the dynamic problems of solid mechanics with crack propagation. In this method, an implicit PD formulation is derived from the bond-based pairwise force that is described as a linear function of the displacements by using the first-order Taylor’s expansion technique. The equivalent incremental equations of the PD method and the finite element method are obtained on the basis of the Newmark and the Newton–Raphson schemes. To combine these two methods, the system is partitioned into two subregions and a convenient and efficient coupling strategy is proposed to form the coupling equivalent equation. The coupling domain is achieved by considering that the nodes and material points share the common information. Furthermore, displacement and load control-based incremental-iterative methods are adopted to solve the nonlinear equations. Several representative numerical examples are carried out and the results demonstrate the effectiveness and accuracy of the proposed coupling method.

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11

Yang, Ming, Jubao Liu, Yuqi Ding, Qianbei Yue, and Qiang Zhang. "A direct numerical simulation method for solid-solid collision and coupling with fluid." Journal of Mechanics 39 (2023): 2–23. http://dx.doi.org/10.1093/jom/ufad001.

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Abstract The collision between solids in fluid is common in engineering, but the numerical simulation method is less studied. A direct numerical simulation method combining the sharp interface immersed boundary method and the finite element method based on penalty function was established for solid–solid collision and coupling with fluid. The lubrication model for cylinder structures with and without fluid flow was developed using the data regression method. The partitioned coupling algorithm was used to realize the coupling solution between the fluid and solid domains. Four numerical examples were presented to demonstrate the validity of the established method. The numerical simulation of the vortex-induced collisions between two side-by-side cylinders showed the capabilities of the proposed method.

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12

Zhang, Yufei, Jingtao Du, and Yang Liu. "Vibro-Acoustic Energy Transmission Analysis of the Acoustic Cavity with Multiple Partial Partitions." Symmetry 13, no. 12 (November 26, 2021): 2257. http://dx.doi.org/10.3390/sym13122257.

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The general dynamic characteristics of the acoustic cavity with multiple partial partitions are presented in this thesis. A theoretical model has been developed for predictions, and several configurations are analyzed. To describe the apertures on the interface of subcavities, the virtual air panel assumption is introduced into the improved Fourier series system. The governing equations of the coupling system are derived by using the energy principle. The results obtained with the proposed model are firstly compared with the numerical calculations based on the finite element method (FEM). Subsequently, a configuration made up from a rigid cavity partitioned by a partial steel panel has been specifically built, and the forced responses of the coupling system have been measured for comparison and model validation. The present results are excellent over most of the studied frequency range. Furthermore, the visualizations of the interior sound intensity field of the acoustic cavity with three partial partitions under different frequencies are researched to illustrate the energy transmission paths and vibro-acoustic coupling mechanism of the complicated system. The obtained results are believed to be helpful in the optimal design of the vibro-acoustic coupling system with optimal sound insulation capacity.

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13

He, Tao. "On a Partitioned Strong Coupling Algorithm for Modeling Fluid–Structure Interaction." International Journal of Applied Mechanics 07, no. 02 (April 2015): 1550021. http://dx.doi.org/10.1142/s1758825115500210.

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This paper presents a partitioned strong coupling algorithm for fluid–structure interaction in the arbitrary Lagrangian–Eulerian finite element framework. The incompressible Navier–Stokes equations are solved by the semi-implicit characteristic-based split (CBS) scheme while the structural equations are temporally advanced by the Bathe method. The celled-based smoothed finite element method is adopted for the solution of a geometrically nonlinear solid. To update the dynamic mesh, the moving submesh approach is performed in conjunction with the ortho-semi-torsional spring analogy method. A mass source term is implanted into the pressure Poisson equation to respect the geometric conservation law for the fractional-step-type CBS fluid solver. The iterative solution is achieved by fixed-point method with Aitken's Δ2 accelerator. The proposed methodology is validated against flow-induced oscillations of a bluff body and a flexible body. The overall numerical results agree well with the available data. Some important flow phenomena have been disclosed successfully.

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14

Gao, Yichao, Feng Jin, Xiang Wang, and Jinting Wang. "Finite Element Analysis of Dam-Reservoir Interaction Using High-Order Doubly Asymptotic Open Boundary." Mathematical Problems in Engineering 2011 (2011): 1–23. http://dx.doi.org/10.1155/2011/210624.

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The dam-reservoir system is divided into the near field modeled by the finite element method, and the far field modeled by the excellent high-order doubly asymptotic open boundary (DAOB). Direct and partitioned coupled methods are developed for the analysis of dam-reservoir system. In the direct coupled method, a symmetric monolithic governing equation is formulated by incorporating the DAOB with the finite element equation and solved using the standard time-integration methods. In contrast, the near-field finite element equation and the far-field DAOB condition are separately solved in the partitioned coupled methodm, and coupling is achieved by applying the interaction force on the truncated boundary. To improve its numerical stability and accuracy, an iteration strategy is employed to obtain the solution of each step. Both coupled methods are implemented on the open-source finite element code OpenSees. Numerical examples are employed to demonstrate the performance of these two proposed methods.

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15

Yusa, Yasunori, and Shinobu Yoshimura. "2309 An Application of Partitioned Iterative Coupling Method to Elasto-plastic Crack Analysis." Proceedings of The Computational Mechanics Conference 2013.26 (2013): _2309–1_—_2309–2_. http://dx.doi.org/10.1299/jsmecmd.2013.26._2309-1_.

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16

He, Tao. "A Partitioned Implicit Coupling Strategy for Incompressible Flow Past an Oscillating Cylinder." International Journal of Computational Methods 12, no. 02 (March 2015): 1550012. http://dx.doi.org/10.1142/s0219876215500127.

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A partitioned implicit coupling strategy is proposed for fluid–structure interaction (FSI) problems in this paper. The incompressible Navier–Stokes equations under arbitrary Lagrangian–Eulerian description are solved by the characteristic-based split scheme while the structural equation is evaluated by the composite implicit time integration method. Moving submesh approach is performed for the mesh deformation and a mass source term (MST) is introduced into the pressure Poisson equation for respecting geometric conservation law. Fluid-structure coupling is achieved by the combined interface boundary condition (CIBC) method. The iterative loops are realized by fixed-point iterations with Aitken's Δ2 method. A structural force predictor is employed within the present algorithm, ensuring that the latest quantities belonging to different subdomains are adopted for the CIBC method. The proposed methodology is validated by flow-induced oscillations of a bluff body. The obtained results agree with the well-documented data. Some well-known flow phenomena have been detected successfully.

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17

González, Jose A., K. C. Park, and Ramon Abascal. "A Partitioned Formulation for FEM/BEM Coupling in Contact Problems Using Localized Lagrange Multipliers." Key Engineering Materials 618 (July 2014): 23–48. http://dx.doi.org/10.4028/www.scientific.net/kem.618.23.

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This paper presents a state-of-the-art in the use of localized Lagrange multipliers (LLMs)for 3D frictional contact problems coupling the Finite Element Method (FEM) and the BoundaryElement Method (BEM). Resolution methods for the contact problem between non-matching mesheshave traditionally been based on a direct coupling of the contacting solids using classical Lagrangemultipliers. These methods tend to generate strongly coupled systems that require a deep knowledgeof the discretization characteristics on each side of the contact zone complicating the process ofmixing different numerical techniques. In this work a displacement contact frame is inserted betweenthe FE and BE interface meshes, discretized and ﬁnally connected to the contacting substructuresusing LLMs collocated at the mesh-interface nodes. This methodology will provide a partitionedformulation which preserves software modularity and facilitates the connection of non-matching FEand BE meshes.

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18

Totounferoush, Amin, Frédéric Simonis, Benjamin Uekermann, and Miriam Schulte. "Efficient and Scalable Initialization of Partitioned Coupled Simulations with preCICE." Algorithms 14, no. 6 (May 27, 2021): 166. http://dx.doi.org/10.3390/a14060166.

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preCICE is an open-source library, that provides comprehensive functionality to couple independent parallelized solver codes to establish a partitioned multi-physics multi-code simulation environment. For data communication between the respective executables at runtime, it implements a peer-to-peer concept, which renders the computational cost of the coupling per time step negligible compared to the typical run time of the coupled codes. To initialize the peer-to-peer coupling, the mesh partitions of the respective solvers need to be compared to determine the point-to-point communication channels between the processes of both codes. This initialization effort can become a limiting factor, if we either reach memory limits or if we have to re-initialize communication relations in every time step. In this contribution, we remove two remaining bottlenecks: (i) We base the neighborhood search between mesh entities of two solvers on a tree data structure to avoid quadratic complexity, and (ii) we replace the sequential gather-scatter comparison of both mesh partitions by a two-level approach that first compares bounding boxes around mesh partitions in a sequential manner, subsequently establishes pairwise communication between processes of the two solvers, and finally compares mesh partitions between connected processes in parallel. We show, that the two-level initialization method is fives times faster than the old one-level scheme on 24,567 CPU-cores using a mesh with 628,898 vertices. In addition, the two-level scheme is able to handle much larger computational meshes, since the central mesh communication of the one-level scheme is replaced with a fully point-to-point mesh communication scheme.

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19

Olivier, Mathieu, and Olivier Paré-Lambert. "Strong fluid–solid interactions with segregated CFD solvers." International Journal of Numerical Methods for Heat & Fluid Flow 29, no. 7 (July 1, 2019): 2237–52. http://dx.doi.org/10.1108/hff-09-2018-0497.

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Purpose This paper aims to present a fluid-structure coupling partitioned scheme involving rigid bodies supported by spring-damper systems. This scheme can be used with already existing fluid flow solvers without the need to modify them. Design/methodology/approach The scheme is based on a modified Broyden method. It solves the equations of solid body motion in which the external forces coming from the flow are provided by a segregated flow solver used as a black box. The whole scheme is implicit. Findings The proposed partitioned method is stable even in the ultimate case of very strong fluid–solid interactions involving a massless cylinder oscillating with no structural damping. The overhead associated with the coupling scheme represents an execution time increase by a factor of about 2 to 5, depending on the context. The scheme also has the advantage of being able to incorporate turbulence modeling directly through the flow solver. It has been tested successfully with URANS simulations without wall law, thus involving thin high aspect-ratio cells near the wall. Originality/value Such problems are known to be very difficult to solve and previous studies usually rely on monolithic approaches. To the authors' knowledge, this is the first time a partitioned scheme is used to solve fluid–solid interactions involving massless components.

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20

Yang, Zhi-Bo, Hao-Qi Li, Bai-Jie Qiao, and Xue-Feng Chen. "Wavelet Element Modelling for Inviscid Fluid–Solid Coupling Problem based on Partitioned Approach." Materials 13, no. 17 (August 21, 2020): 3699. http://dx.doi.org/10.3390/ma13173699.

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To provide a simple numerical formulation based on fixed grids, a wavelet element method for fluid–solid modelling is introduced in this work. Compared with the classical wavelet finite element method, the presented method can potentially handle more complex shapes. Considering the differences between the solid and fluid regions, a damping-like interface based on wavelet elements is designed, in order to ensure consistency between the two parts. The inner regions are constructed with the same wavelet function in space. In the time and spatial domains, a partitioned approach based on Jacobi iteration is combined with the pseudo-parallel calculation method. Numerical convergence analyses show that the method can serve as an alternative choice for fluid–solid coupling modelling.

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21

Yamada, Kai, Yasunori Yusa, Tomonori Yamada, and Shinobu Yoshimura. "116 Convergence Improvement of Partitioned Coupling Method for Solid-Solid Interaction Analysis with Cracks." Proceedings of The Computational Mechanics Conference 2015.28 (2015): _116–1_—_116–3_. http://dx.doi.org/10.1299/jsmecmd.2015.28._116-1_.

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22

Feng, Huaize, Tongren Xu, Liangyun Liu, Sha Zhou, Jingxue Zhao, Shaomin Liu, Ziwei Xu, et al. "Modeling Transpiration with Sun-Induced Chlorophyll Fluorescence Observations via Carbon-Water Coupling Methods." Remote Sensing 13, no. 4 (February 22, 2021): 804. http://dx.doi.org/10.3390/rs13040804.

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Successfully applied in the carbon research area, sun-induced chlorophyll fluorescence (SIF) has raised the interest of researchers from the water research domain. However, current works focused on the empirical relationship between SIF and plant transpiration (T), while the mechanistic linkage between them has not been fully explored. Two mechanism methods were developed to estimate T via SIF, namely the water-use efficiency (WUE) method and conductance method based on the carbon–water coupling framework. The T estimated by these two methods was compared with T partitioned from eddy covariance instrument measured evapotranspiration at four different sites. Both methods showed good performance at the hourly (R2 = 0.57 for the WUE method and 0.67 for the conductance method) and daily scales (R2 = 0.67 for the WUE method and 0.78 for the conductance method). The developed mechanism methods provide theoretical support and have a great potential basis for deriving ecosystem T by satellite SIF observations.

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23

Ogino, Masao, Takuya Iwama, and Mitsuteru Asai. "Development of a Partitioned Coupling Analysis System for Fluid–Structure Interactions Using an In-House ISPH Code and the Adventure System." International Journal of Computational Methods 16, no. 04 (May 13, 2019): 1843009. http://dx.doi.org/10.1142/s0219876218430090.

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In this paper, a partitioned coupling analysis system is developed for a numerical simulation of 3-dimensional fluid–structure interaction (FSI) problems, adopting an incompressible smoothed particle hydrodynamics (SPH) method for fluid dynamics involving free surface flow and the finite element method (FEM) for structural dynamics. A coupling analysis of a particle-based method and a grid-based method has been investigated. However, most of these are developed as a function-specific application software, and therefore lack versatility. Hence, to save cost in software development and maintenance, the open source software is utilized. Especially, a general-purpose finite element analysis system, named ADVENTURE, and a general-purpose coupling analysis platform, named REVOCAP_Coupler, are employed. Moreover, techniques of an interface marker on fluid–structure boundaries and a dummy mesh for fluid analysis domain are adopted to solve the problem that the REVOCAP_Coupler performs to unify two or more grid-based method codes. To verify a developed system, the dam break problem with an elastic obstacle is demonstrated, and the result is compared with the results calculated by the other methods.

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24

Hong, Giwon, Tomonori Yamada, and Shinobu Yoshimura. "065 Simulation and Evaluation of Flapping Motion Considering Passive Feathering by Partitioned Iterative Coupling Method." Proceedings of The Computational Mechanics Conference 2015.28 (2015): _065–1_—_065–2_. http://dx.doi.org/10.1299/jsmecmd.2015.28._065-1_.

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25

Lim, W. Z., and R. Y. Xiao. "Fluid-structure interaction analysis of gravity-based structure (GBS) offshore platform with partitioned coupling method." Ocean Engineering 114 (March 2016): 1–9. http://dx.doi.org/10.1016/j.oceaneng.2015.12.059.

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26

He, Tao. "A CBS-based partitioned semi-implicit coupling algorithm for fluid–structure interaction using MCIBC method." Computer Methods in Applied Mechanics and Engineering 298 (January 2016): 252–78. http://dx.doi.org/10.1016/j.cma.2015.09.020.

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27

Bukač, Martina. "An Extension of Explicit Coupling for Fluid–Structure Interaction Problems." Mathematics 9, no. 15 (July 24, 2021): 1747. http://dx.doi.org/10.3390/math9151747.

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We present an extension of a non-iterative, partitioned method previously designed and used to model the interaction between an incompressible, viscous fluid and a thick elastic structure. The original method is based on the Robin boundary conditions and it features easy implementation and unconditional stability. However, it is sub-optimally accurate in time, yielding only O(Δt12) rate of convergence. In this work, we propose an extension of the method designed to improve the sub-optimal accuracy. We analyze the stability properties of the proposed method, showing that the method is stable under certain conditions. The accuracy and stability of the method are computationally investigated, showing a significant improvement in the accuracy when compared to the original scheme, and excellent stability properties. Furthermore, since the method depends on a combination parameter used in the Robin boundary conditions, whose values are problem specific, we suggest and investigate formulas according to which this parameter can be determined.

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28

Davis, Kyle, Miriam Schulte, and Benjamin Uekermann. "Enhancing Quasi-Newton Acceleration for Fluid-Structure Interaction." Mathematical and Computational Applications 27, no. 3 (May 6, 2022): 40. http://dx.doi.org/10.3390/mca27030040.

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We propose two enhancements of quasi-Newton methods used to accelerate coupling iterations for partitioned fluid-structure interaction. Quasi-Newton methods have been established as flexible, yet robust, efficient and accurate coupling methods of multi-physics simulations in general. The coupling library preCICE provides several variants, the so-called IQN-ILS method being the most commonly used. It uses input and output differences of the coupled solvers collected in previous iterations and time steps to approximate Newton iterations. To make quasi-Newton methods both applicable for parallel coupling (where these differences contain data from different physical fields) and to provide a robust approach for re-using information, a combination of information filtering and scaling for the different physical fields is typically required. This leads to good convergence, but increases the cost per iteration. We propose two new approaches—pre-scaling weight monitoring and a new, so-called QR3 filter, to substantially improve runtime while not affecting convergence quality. We evaluate these for a variety of fluid-structure interaction examples. Results show that we achieve drastic speedups for the pure quasi-Newton update steps. In the future, we intend to apply the methods also to volume-coupled scenarios, where these gains can be decisive for the feasibility of the coupling approach.

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29

Tian, Fang-Bao, Yong Wang, John Young, and Joseph C. S. Lai. "An FSI solution technique based on the DSD/SST method and its applications." Mathematical Models and Methods in Applied Sciences 25, no. 12 (August 24, 2015): 2257–85. http://dx.doi.org/10.1142/s0218202515400084.

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This paper presents a fluid–structure interaction (FSI) solution technique in which the incompressible fluid dynamics involving moving boundaries is solved with the deforming-spatial-domain/stabilized space–time (DSD/SST) method and the structural dynamics is solved with the finite difference (FD) method. The DSD/SST and FD solvers are coupled by an implicit partitioned coupling strategy based on staggered subiterations. Three types of relaxation are applied on the FSI surface velocity and hydrodynamic force. The first one is applied to delay the coupling conditions at the beginning of each simulation; the second one is applied to relax the increment during each subiteration; and the third one is applied to filter high frequency oscillations between each time step. A pitching plate in a uniform flow is calculated to validate the FSI technique. The present results are in good agreement with data predicted by other methods. In addition, two problems are calculated to demonstrate the capability of this solver: an orbital flow over flapping foil propulsion and energy harvesting and a flexible plate in a cavity excited by an external force.

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30

Chen, Hao, Min Xu, Zihua Qiu, Dan Xie, and Yabin Wang. "Aerothermoelastic Load Calculation for Hypersonic Vehicles Based on Multiphysics Coupled Analysis." Mathematical Problems in Engineering 2018 (September 18, 2018): 1–15. http://dx.doi.org/10.1155/2018/6051924.

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To fulfill the design objective of a structure and thermal protection system, accurate load environment prediction is very important, so we present a high-fidelity aerothermoelastic load calculation method based on a partitioned computational fluid dynamics/computational structural dynamics/computational thermal dynamics (CFD/CSD/CTD) coupling analysis. For the data transformation between the CFD/CSD/CTD systems, finite element interpolation (FEI) is explored, and a shape-preserving grid deformation strategy is achieved via radical basis functions (RBFs). Numerical results are presented for validation of the proposed CFD/CSD/CTD coupling analysis. First, a simply supported panel in hypersonic flow is investigated for results comparison of the proposed coupling method and previous work. Second, a hypersonic forebody is investigated to explore the aerothermoelastic effects while considering the feedback between deformation and aerodynamic heating. The results show that the CFD/CSD/CTD coupling method is accurate for analysis of aerothermoelasticity. In addition, considering the aerothermoelastic effect, the shear force and bending movement increase with time before 900s and decrease after 900s, and at 900s increased percentages of 5.7% and 4.1% are observed, respectively. Therefore, it is necessary to adopt high-fidelity CFD/CSD/CTD coupling in the design of a structure and thermal protection system for hypersonic vehicles.

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31

Sautter, Klaus Bernd, Tobias Teschemacher, Miguel Ángel Celigueta, Philipp Bucher, Kai-Uwe Bletzinger, and Roland Wüchner. "Partitioned Strong Coupling of Discrete Elements with Large Deformation Structural Finite Elements to Model Impact on Highly Flexible Tension Structures." Advances in Civil Engineering 2020 (November 20, 2020): 1–28. http://dx.doi.org/10.1155/2020/5135194.

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This article presents a staggered approach to couple the interaction of very flexible tension structures with large deformations, described with the finite element method (FEM), and objects undergoing large, complex, and arbitrary motions discretized with particle methods, in this case the discrete element method (DEM). The quantitative solution quality and convergence rate of this partitioned approach is highly time step dependent. Thus, the strong coupling approach is presented here, where the convergence is achieved in an iterative manner within each time step. This approach helps increase the time step size significantly, decreases the overall computational costs, and improves the numerical stability. Moreover, the proposed algorithm enables the application of two independent, standalone codes for simulating DEM and structural FEM as blackbox solvers. Systematic evaluations of the newly proposed iterative coupling scheme with respect to accuracy, robustness, and efficiency as well as cross comparisons between strong and weak FEM-DEM coupling approaches are performed. Additionally, the approach is validated against the rest position of an impacting object, and further examples with objects impacting highly flexible protection structures are presented. Here, the protection nets are described with nonlinear structural finite elements and the impacting objects as DEM elements. To allow the interested reader to independently reproduce the results, detailed code and algorithm descriptions are included in the appendix.

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32

Li, Zhi Miao, Ju Bao Liu, Min Luo, and Qiang Zhang. "Dynamic Finite Element Analysis and Experimental Study of Rotating Column in Cylinder." Applied Mechanics and Materials 229-231 (November 2012): 453–56. http://dx.doi.org/10.4028/www.scientific.net/amm.229-231.453.

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Rotary slender column in cylinder is a special structure in oil engineering. It contacts with outer cylinder and interacts with its inner pipe fluid and outer annular fluid. A partitioned coupling model was founded by dispersing slender column into beam element, dividing fluid domain into some sections, dispersing fluid section into hexahedron unit and transfer method of the information of coupling interface was described. Dynamics experimental device of column-liquid interaction was built to do column rotating test with considering the displacement and force boundary conditions of rotating column and testing axial excitation force of bottom column, axial acceleration of head column, transverse displacement of columns and collision and contact forces between inner columns and outer pipeline. The maximum absolute error between experimental results and numerical results is 0.31mm and this research provides the methods of numerical simulation and experimental study.

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33

AIKAWA, Shoichi, Daisuke ISHIHARA, Takeru KUMAGAI, Naoki IWAMARU, P. C. RAMAGOWDA, and Minato OONISHI. "A Study on Partitioned Iterative Method for Piezoelectric, Inverse Piezoelectric and Structural Coupling in Electro-Mechanical Systems." Proceedings of The Computational Mechanics Conference 2021.34 (2021): 249. http://dx.doi.org/10.1299/jsmecmd.2021.34.249.

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34

Racca, Alberto, Tom Verstraete, and Lorenzo Casalino. "Radial Turbine Thermo-Mechanical Stress Optimization by Multidisciplinary Discrete Adjoint Method." International Journal of Turbomachinery, Propulsion and Power 5, no. 4 (November 25, 2020): 30. http://dx.doi.org/10.3390/ijtpp5040030.

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This paper addresses the problem of the design optimization of turbomachinery components under thermo-mechanical constraints, with focus on a radial turbine impeller for turbocharger applications. Typically, turbine components operate at high temperatures and are exposed to important thermal gradients, leading to thermal stresses. Dealing with such structural requirements necessitates the optimization algorithms to operate a coupling between fluid and structural solvers that is computationally intensive. To reduce the cost during the optimization, a novel multiphysics gradient-based approach is developed in this work, integrating a Conjugate Heat Transfer procedure by means of a partitioned coupling technique. The discrete adjoint framework allows for the efficient computation of the gradients of the thermo-mechanical constraint with respect to a large number of design variables. The contribution of the thermal strains to the sensitivities of the cost function extends the multidisciplinary outlook of the optimization and the accuracy of its predictions, with the aim of reducing the empirical safety factors applied to the design process. Finally, a turbine impeller is analyzed in a demanding operative condition and the gradient information results in a perturbation of the grid coordinates, reducing the stresses at the rotor back-plate, as a demonstration of the suitability of the presented method.

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35

Prasad, Chandra Shekhar, and Luděk Pešek. "Analysis of classical flutter in steam turbine blades using reduced order aeroelastic model." MATEC Web of Conferences 211 (2018): 15001. http://dx.doi.org/10.1051/matecconf/201821115001.

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In the present paper classical flutter phenomena in LP steam turbine rotor is studied . A reduced order aeroelastic model (ROAM) with acceptable accuracy and fast execution is developed for this purpose. The aerodynamics damping (AD) is estimated using Traveling wave mode (TWM) method. Flow field is modeled using Panel method. For the structural part ROM non-linear beam element method (BEM) based FEM structural solver is used. Partitioned based ( loose) coupling approach is adopted to perform aeroelastic (flutter) cosimulation. Both 2D cascade flow and 3D cascade are modeled.The estimated stability parameters are compared with experimental data. Moreover, present ROAM shows significant reduction in computational time.

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36

Minami, Satsuki, Tomonori Yamada, and Shinobu Yoshimura. "1901 Comparison of Non-linear Coupling Algorithms on the Partitioned Iterative Method for Parallel Computing of FSI Problems." Proceedings of The Computational Mechanics Conference 2007.20 (2007): 159–60. http://dx.doi.org/10.1299/jsmecmd.2007.20.159.

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37

Xie, Fangfang, Dingyi Pan, Yao Zheng, and Jianfeng Zou. "Smoothed profile method and its applications in VIV." International Journal of Numerical Methods for Heat & Fluid Flow 27, no. 7 (July 3, 2017): 1623–35. http://dx.doi.org/10.1108/hff-12-2016-0503.

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Purpose The purpose of this paper is to propose a partitioned approach by coupling the smoothed profile method (SPM) and the Euler tension beam model in simulating a vortex-induced vibration of both rigid and flexible cylinders at various reduced velocities. Design/methodology/approach For the fluid part, SPM in the framework of the spectral element method is adopted to simulate the flow. The advantage of SPM lies in modelling multiple complex shapes as it uses a fixed computational mesh without conformation to the geometry of the particles. For the structure part, an elastic-mounted rigid cylinder is considered in two-dimensional (2D) simulations, while a flexible cylinder with a Euler tension beam model is used in three-dimensional simulations. Findings Firstly, in the flow past a freely vibrating cylinder, the maximum vibration responses of the cylinder are about 0.73D and 0.1D in the y and x directions, respectively, which occur at the point Ur = 5.75 and are much higher than Ur = 5 in 2D simulations. It is found that the numerical results from the SPM solver are very consistent with those from the NEKTAR-Arbitrary Lagrangian Eulerian method (NEKTAR-ALE) solver or the NEKTAR-Fourier solver. Furthermore, the flow past the tandem cylinders is also investigated, where the upstream cylinder is static while the downstream one is free to vibrate. Specifically, the beating behaviour is captured from the vibration response of the freely vibrating cylinder under the reduced velocity of Ur = 6 with a gap distance of L = 3.5D. Originality/value The originality of the paper lies in coupling the SEM with the Euler beam model in simulating the vortex induced vibration (VIV) of flexible cylinders.

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38

Haussmann, Marc, Peter Reinshaus, Stephan Simonis, Hermann Nirschl, and Mathias J. Krause. "Fluid–Structure Interaction Simulation of a Coriolis Mass Flowmeter Using a Lattice Boltzmann Method." Fluids 6, no. 4 (April 20, 2021): 167. http://dx.doi.org/10.3390/fluids6040167.

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In this paper, we use a fluid–structure interaction (FSI) approach to simulate a Coriolis mass flowmeter (CMF). The fluid dynamics is calculated by the open-source framework OpenLB, based on the lattice Boltzmann method (LBM). For the structural dynamics we employ the open-source software Elmer, an implementation of the finite element method (FEM). A staggered coupling approach between the two software packages is presented. The finite element mesh is created by the mesh generator Gmsh to ensure a complete open source workflow. The Eigenmodes of the CMF, which are calculated by modal analysis, are compared with measurement data. Using the estimated excitation frequency, a fully coupled, partitioned, FSI simulation is applied to simulate the phase shift of the investigated CMF design. The calculated phase shift values are in good agreement to the measurement data and verify the suitability of the model to numerically describe the working principle of a CMF.

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39

Sun, Ying, Ding Zhou, Jiadong Wang, Zhenyuan Gu, and Wangping Qian. "Sloshing of Liquid in a Cylindrical Tank with Multiple Baffles and Considering Soil-Structure Interaction." Applied Sciences 12, no. 22 (November 21, 2022): 11841. http://dx.doi.org/10.3390/app122211841.

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In this study, the liquid sloshing in a cylindrical tank considering soil–structure interaction and undergoing horizontal excitation is investigated analytically. Multiple rigid annular baffles are positioned on the rigid wall to mitigate the liquid sloshing. Firstly, combined with the subdomain partition method for sloshing, the complex liquid domain is partitioned into simple subdomains with the single condition for boundary. Based on continuity conditions of velocity and pressure as well as the linear sloshing equation for free surface, the exact solution for convective velocity potential is derived with high accuracy. By yielding the similar hydrodynamic shear and moment as those of the original system, a mechanical model is developed to describe continuous sloshing, and parameters of the model are given in detail. Then, by means of the least squares approach, the Chebyshev polynomials are utilized to fit impedances for the circular surface foundation. A lumped parameter model is employed to represent influences of soil on the superstructure. Finally, by using the substructure method, a coupling model of the soil–tank system is developed to simplify the dynamic analysis. Comparison investigations are carried out to verify the effectiveness of the model. Detailed sloshing characteristics and dynamic responses of sloshing are analyzed with regard to different baffle sizes and positions as well as soil parameters, respectively. The novelty of the present study is that an equivalent analytical model for the soil–foundation–tank–liquid system with multiple baffles is firstly obtained and it allows the dynamic behaviors of the coupling system to be investigated with high computation efficiency and acceptable accuracy.

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40

SATO, Taiki, Makoto YANESHITA, and Masayuki OGURO. "PREDICTING TURF THERMAL ENVIRONMENT IN SPORTS STADIUMS USING COUPLING ANALYSIS OF RADIATION, CONVECTION, AND MOISTURE BASED ON ITERATIVE PARTITIONED METHOD." Journal of Environmental Engineering (Transactions of AIJ) 83, no. 754 (2018): 965–74. http://dx.doi.org/10.3130/aije.83.965.

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41

Yang, Zhao, and Jie Li. "Numerical Aeroelastic Analysis of a High-Aspect-Ratio Wing Considering Skin Flexibility." Aerospace 9, no. 9 (September 15, 2022): 515. http://dx.doi.org/10.3390/aerospace9090515.

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Aeroelastic deformation of the high-aspect-ratio wing from a solar-powered UAV will definitely lead to the difference of its performance between design and actual flight. In the present study, the numerical fluid-structural coupling analysis of a wing with skin flexibility is performed by a loosely coupled partitioned approach. The bidirectional coupling framework is established by combining an in-house developed computational fluid dynamics (CFD) code with a computational structural dynamics (CSD) analysis solver and a time-adaptive coupling strategy is integrated in it to improve the computational stability and efficiency of the process. With the proposed method, the fluid-structure interactions between the wing and fluid are simulated, and the results are compared between the deformed wing and its rigid counterpart regarding the aerodynamic coefficients, transition location, and flow structures at large angles of attack. It can be observed that after deformation, the laminar transition on the upper surface is triggered earlier at small angles of attack and the stall characteristic becomes worse. The calculated difference in aerodynamic performance between the deformed and the designed rigid wing can help designers better understand the wing’s real performance in the preliminary stage of design.

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42

Savino, Alberto, Alessandro Cocco, Alex Zanotti, Matteo Tugnoli, Pierangelo Masarati, and Vincenzo Muscarello. "Coupling Mid-Fidelity Aerodynamics and Multibody Dynamics for the Aeroelastic Analysis of Rotary-Wing Vehicles." Energies 14, no. 21 (October 25, 2021): 6979. http://dx.doi.org/10.3390/en14216979.

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A mid-fidelity aerodynamic solver based on the vortex particle method for wake modeling, DUST, is coupled through the partitioned multi-physics coupling library preCICE to a multibody dynamics code, MBDyn, to improve the accuracy of aeroelastic numerical analysis performed on rotary-wing vehicles. In this paper, the coupled tool is firstly validated by solving simple fixed-wing and rotary-wing problems from the open literature. The transient roll maneuver of a complete tiltrotor aircraft is then simulated, to show the capability of the coupled solver to analyze the aeroelasticity of complex rotorcraft configurations. Simulation results show the importance of the accurate representation of rotary wing aerodynamics provided by the vortex particle method for loads evaluation, aeroelastic stability assessment, and analysis of transient maneuvers of aircraft configurations characterized by complex interactional aerodynamics. The limited computational effort required by the mid-fidelity aerodynamic approach represents an effective trade-off in obtaining fast and accurate solutions that can be used for the preliminary design of novel rotary-wing vehicle configurations.

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43

Fahmy, Mohamed Abdelsabour. "A Computational Model for Nonlinear Biomechanics Problems of FGA Biological Soft Tissues." Applied Sciences 12, no. 14 (July 16, 2022): 7174. http://dx.doi.org/10.3390/app12147174.

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The principal objective of this work was to develop a semi-implicit hybrid boundary element method (HBEM) to describe the nonlinear fractional biomechanical interactions in functionally graded anisotropic (FGA) soft tissues. The local radial basis function collocation method (LRBFCM) and general boundary element method (GBEM) were used to solve the nonlinear fractional dual-phase-lag bioheat governing equation. The boundary element method (BEM) was then used to solve the poroelastic governing equation. To solve equations arising from boundary element discretization, an efficient partitioned semi-implicit coupling algorithm was implemented with the generalized modified shift-splitting (GMSS) preconditioners. The computational findings are presented graphically to display the influences of the graded parameter, fractional parameter, and anisotropic property on the bio-thermal stress. Different bioheat transfer models are presented to show the significant differences between the nonlinear bio-thermal stress distributions in functionally graded anisotropic biological tissues. Numerical findings verified the validity, accuracy, and efficiency of the proposed method.

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44

Chaudhuri, Arjun, Sanmitra Banerjee, Jinwoo Kim, Heechun Park, Bon Woong Ku, Sukeshwar Kannan, Krishnendu Chakrabarty, and Sung Kyu Lim. "Built-in Self-Test and Fault Localization for Inter-Layer Vias in Monolithic 3D ICs." ACM Journal on Emerging Technologies in Computing Systems 18, no. 1 (January 31, 2022): 1–37. http://dx.doi.org/10.1145/3464430.

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Monolithic 3D (M3D) integration provides massive vertical integration through the use of nanoscale inter-layer vias (ILVs). However, high integration density and aggressive scaling of the inter-layer dielectric make ILVs especially prone to defects. We present a low-cost built-in self-test (BIST) method that requires only two test patterns to detect opens, stuck-at faults, and bridging faults (shorts) in ILVs. We also propose an extended BIST architecture for fault detection, called Dual-BIST, to guarantee zero ILV fault masking due to single BIST faults and negligible ILV fault masking due to multiple BIST faults. We analyze the impact of coupling between adjacent ILVs arranged in a 1D array in block-level partitioned designs. Based on this analysis, we present a novel test architecture called Shared-BIST with the added functionality of localizing single and multiple faults, including coupling-induced faults. We introduce a systematic clustering-based method for designing and integrating a delay bank with the Shared-BIST architecture for testing small-delay defects in ILVs with minimal yield loss. Simulation results for four two-tier M3D benchmark designs highlight the effectiveness of the proposed BIST framework.

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45

Qiu, C., B. Raverdy, and V. Faucher. "Development of a partitioned coupling method based on multi-scale data exchanges between porous and CFD solvers for a nuclear core." Annals of Nuclear Energy 180 (January 2023): 109470. http://dx.doi.org/10.1016/j.anucene.2022.109470.

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46

Zhou, Heng, Xiaofan An, Ying Zhang, Xuguang Chen, Shengjie Di, and Xi Lu. "Study on Formation Mechanism of Zonal Disintegration of Surrounding Rock in Deep Tunnel." E3S Web of Conferences 276 (2021): 01018. http://dx.doi.org/10.1051/e3sconf/202127601018.

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With the construction of underground rock engineering, the surrounding rock in deep tunnels appears zonal disintegration of fracture and intact zones alternate distribution, which is a special engineering geological phenomenon. This study establishes a partitioned fracture model under the coupling of high in-situ stress and osmotic pressure, and identify the key influencing factors of the fracture model. Furthermore, a stress intensity factor (SIF) of initial cracks on surrounding rock elastoplastic boundary is derived using the transformation of complex functions. Considering the high seepage pressure of the surrounding rocks, a zonal fracture initiation criterion is established combined with the analysis of redistributed stress fields. Finally, the obtained criterion is embedded into an extended finite element method (XFEM) platform for numerical simulation. Taking the maximum circumferential tensile stress as a cracking criterion, the propagation trajectory of rock cracks is traced by contour methods. Calculation results have realized the modelling of a whole process of crack initiation, propagation, and formation. And the established criterion has be verified.

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47

Xu, Yuan-Qing, Yan-Qun Jiang, Jie Wu, Yi Sui, and Fang-Bao Tian. "Benchmark numerical solutions for two-dimensional fluid–structure interaction involving large displacements with the deforming-spatial-domain/stabilized space–time and immersed boundary–lattice Boltzmann methods." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 232, no. 14 (August 1, 2017): 2500–2514. http://dx.doi.org/10.1177/0954406217723942.

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Body-fitted and Cartesian grid methods are two typical types of numerical approaches used for modelling fluid–structure interaction problems. Despite their extensive applications, there is a lack of comparing the performance of these two types of approaches. In order to do this, the present paper presents benchmark numerical solutions for two two-dimensional fluid–structure interaction problems: flow-induced vibration of a highly flexible plate in an axial flow and a pitching flexible plate. The solutions are obtained by using two partitioned fluid–structure interaction methods including the deforming-spatial-domain/stabilized space–time fluid–structure interaction solver and the immersed boundary–lattice Boltzmann method. The deforming-spatial-domain/stabilized space–time fluid–structure interaction solver employs the body-fitted-grid deforming-spatial-domain/stabilized space–time method for the fluid motions and the finite-difference method for the structure vibrations. A new mesh update strategy is developed to prevent severe mesh distortion in cases where the boundary does not oscillate periodically or needs a long time to establish a periodic motion. The immersed boundary–lattice Boltzmann method uses lattice Boltzmann method as fluid solver and the same finite-difference method as structure solver. In addition, immersed boundary method is used in the immersed boundary–lattice Boltzmann solver to handle the fluid–structure interaction coupling. Results for the characteristic force coefficients, tail position, plate deformation pattern and the vorticity fields are presented and discussed. The present results will be useful for evaluating the performance and accuracy of existing and new numerical methodologies for fluid–structure interaction.

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48

Ngo, Linh Dan, Dumitru Duca, Yvain Carpentier, Jennifer A. Noble, Raouf Ikhenazene, Marin Vojkovic, Cornelia Irimiea, et al. "Chemical discrimination of the particulate and gas phases of miniCAST exhausts using a two-filter collection method." Atmospheric Measurement Techniques 13, no. 2 (February 28, 2020): 951–67. http://dx.doi.org/10.5194/amt-13-951-2020.

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Abstract. Combustion of hydrocarbons produces both particulate- and gas-phase emissions responsible for major impacts on atmospheric chemistry and human health. Ascertaining the impact of these emissions, especially on human health, is not straightforward because of our relatively poor knowledge of how chemical compounds are partitioned between the particle and gas phases. Accordingly, we propose coupling a two-filter sampling method with a multi-technique analytical approach to fully characterize the particulate- and gas-phase compositions of combustion by-products. The two-filter sampling method is designed to retain particulate matter (elemental carbon possibly covered in a surface layer of adsorbed molecules) on a first quartz fiber filter while letting the gas phase pass through and then trap the most volatile components on a second black-carbon-covered filter. All samples thus collected are subsequently subjected to a multi-technique analytical protocol involving two-step laser mass spectrometry (L2MS), secondary ion mass spectrometry (SIMS), and micro-Raman spectroscopy. Using the combination of this two-filter sampling–multi-technique approach in conjunction with advanced statistical methods, we are able to unravel distinct surface chemical compositions of aerosols generated with different set points of a miniCAST burner. Specifically, we successfully discriminate samples by their volatile, semi-volatile, and non-volatile polycyclic aromatic hydrocarbon (PAH) contents and reveal how subtle changes in combustion parameters affect particle surface chemistry.

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49

Geng, Meixia, J. Kim Welford, Colin G. Farquharson, Alexander L. Peace, and Xiangyun Hu. "3-D joint inversion of airborne gravity gradiometry and magnetic data using a probabilistic method." Geophysical Journal International 223, no. 1 (June 18, 2020): 301–22. http://dx.doi.org/10.1093/gji/ggaa283.

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SUMMARY A probabilistic approach is presented for jointly inverting gravity gradient and magnetic data for 3-D subsurface distributions of density and magnetic susceptibility. The coupling of the physical property models is incorporated in the inversion by using a cross-covariance matrix of density and magnetic susceptibility. This enables structural similarity such as the orientation and spatial extent of the sources and cross-variance between the two physical properties to be incorporated. A user-defined correlation coefficient can control the level of similarity between the two models. By applying a marginalizing algorithm in the joint inversion, the inversion domain is allowed to be partitioned into various zones, each of which can have its own covariance, cross-covariance matrix, as well as correlation coefficient, depending upon the feature and similarity of sources. Thus, sources with different shapes, sizes and relationships between the two physical properties can be simultaneously recovered. The validity of the method is verified using three synthetic examples, which demonstrate how incorrect parameters of the cross-covariance matrix affect the inverted results. Finally, the proposed method is successfully applied to full tensor gradiometry and magnetic data collected over the Budgell Harbour Stock (BHS) intrusion in north-central Newfoundland, Canada. Compared with models generated from independent inversions, better definition and localization of the main intrusion, as well as associated lamprophyre dykes at shallow depth, are achieved by using the joint inversion. The resolved physical properties for the intrusions show good agreement with field observations of lamprophyre dykes in proximity to the BHS.

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50

DÜTSCH, H., F. DURST, and A. MELLING. "Fluid–structure interactions of a torsion spring pendulum at large initial amplitudes." Journal of Fluid Mechanics 471 (November 5, 2002): 219–38. http://dx.doi.org/10.1017/s0022112002002057.

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The motion of a lamina of high aspect ratio suspended in a Newtonian fluid was studied experimentally and numerically. The damped oscillations for one rotational degree of freedom showed strong nonlinear fluid–structure interactions, mainly caused by the vortex structures forming at the lamina tips. The numerical results were obtained by a fully implicit Navier–Stokes solver, using partitioned coupling of the equations of motion of the fluid and suspended structure. Computations were carried out for different grid levels and time steps, providing information on the accuracy of the numerical results. For the fluid domain, a Langrangian–Eulerian finite-volume method was applied in order to solve the two-dimensional Navier–Stokes equation on grids moving with the oscillating lamina. The elastic motion of the lamina was computed as that of a torsion spring pendulum. The computed time traces of the angular position are in close agreement with corresponding experimental results. An equivalent empirical model which accounted for the fluid moments by empirical coefficients was much less successful in predicting the experimentally observed behaviour.

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