The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Jianming Jin - One of the best experts on this subject based on the ideXlab platform.

  • an accurate and efficient finite element boundary integral Method with gpu acceleration for 3 d electromagnetic analysis
    IEEE Transactions on Antennas and Propagation, 2014
    Co-Authors: Jian Guan, Su Yan, Jianming Jin
    Abstract:

    An accurate and efficient finite element-boundary integral (FE-BI) Method with graphics processing unit (GPU) acceleration is presented for solving electromagnetic problems with complex structures and materials. A mixed testing scheme, in which the Rao-Wilton-Glisson and the Buffa-Christiansen functions are both employed as the testing functions, is first presented to improve the accuracy of the FE-BI Method. An efficient absorbing boundary condition (ABC)-based preconditioner is then proposed to accelerate the convergence of the iterative solution. To further improve the efficiency of the total computation, a GPU-accelerated multilevel fast multipole algorithm (MLFMA) is applied to the iterative solution. The radar cross sections (RCS) of several benchmark objects are calculated to demonstrate the numerical accuracy of the solution and also to show that the proposed Method not only is free of interior resonance corruption, but also has a better convergence than the conventional FE-BI Methods. The capability and efficiency of the proposed Method are analyzed through several numerical examples, including a large dielectric coated sphere, a partial human body, and a coated missile-like object. Compared with the 8-threaded CPU-based algorithm, the GPU-accelerated FE-BI-MLFMA algorithm can achieve a total speedup up to 25.5 times.

  • a higher order finite element boundary integral Method for electromagnetic scattering from bodies of revolution
    IEEE Antennas and Propagation Society International Symposium, 2005
    Co-Authors: Eric Dunn, Jinkyu Byun, Jianming Jin
    Abstract:

    A higher-order finite element - boundary integral (FE-BI) Method is presented to calculate the radar cross section (RCS) of body-of-revolution (BOR) geometries. The Method is based on a finite element Method (FEM) that uses higher-order nodal based scalar functions for the azimuthal field components and higher-order edge based vector basis for the transverse field. The FEM mesh is truncated with a boundary integral based on a first order Method of moments (MoM). Such a Method is void of spurious modes and more accurate than earlier first order formulations

  • a higher order finite element boundary integral Method for electromagnetic scattering and radiation from bodies of revolution
    Ph.D. Thesis, 2005
    Co-Authors: Jianming Jin, Eric Dunn
    Abstract:

    The hybrid finite element - boundary integral Method (FE-BI) is used to compute the radar cross section (RCS) and radiated fields of bodies of revolution (BOR). This is a 2.5-D problem since it allows simulations in a 2-D domain to correspond to a full 3-D object. The interior region, which corresponds to the local near-field of the scatterer/radiator is modeled with a higher-order finite element Method (FEM) using interpolatory mixed node/vector basis functions. The radiation condition for the exterior region is enforced by using the Method of moments (MoM) to form a boundary integral to enclose the interior region. Scattering problems are excited by a uniform plane wave which is decomposed into a superposition of cylindrical waves. Likewise, radiation problems are excited by local current sources which are decomposed into a Fourier series. For both scattering and radiation analysis each Fourier/cylindrical mode can be evaluated independently. The FE-BI Method very accurately models the fields generated by any BOR. Increasing the order of the basis functions is shown to further improve the accuracy.

  • a fast higher order time domain finite element boundary integral Method for 3 d electromagnetic scattering analysis
    IEEE Transactions on Antennas and Propagation, 2002
    Co-Authors: Dan Jiao, Balasubramaniam Shanker, Eric Michielssen, A. Arif Ergin, Jianming Jin
    Abstract:

    A novel hybrid time-domain finite element-boundary integral Method for analyzing three-dimensional (3-D) electromagnetic scattering phenomena is presented. The Method couples finite element and boundary integral field representations in a way that results in a sparse system matrix and solutions that are devoid of spurious modes. To accurately represent the unknown fields, the scheme employs higher-order vector basis functions defined on curvilinear tetrahedral elements. To handle problems involving electrically large objects, the multilevel plane-wave time-domain algorithm is used to accelerate the evaluation of the boundary integrals. Numerical results demonstrate the accuracy and versatility of the proposed scheme.

  • a fast higher order time domain finite element boundary integral Method for 3 d electromagnetic scattering analysis
    IEEE Antennas and Propagation Society International Symposium, 2001
    Co-Authors: Dan Jiao, Balasubramaniam Shanker, Eric Michielssen, A. Arif Ergin, Jianming Jin
    Abstract:

    We present a hybrid time-domain finite element-boundary integral (FE-BI) Method for analyzing 3D electromagnetic open-region transient scattering phenomena. This Method has three unique features. The first is the hybridization scheme that combines the FE and BI representations of the fields. Instead of following the standard hybridization scheme used in the frequency domain, we propose a novel scheme that preserves the sparsity of the finite element matrix and that yields solutions free of spurious modes associated with interior BI resonances. The second feature is the use of a fast algorithm, the multilevel plane-wave time-domain (PWTD) Method, for evaluating the BI. Invoking this scheme greatly reduces the computational expense when an object of large electrical dimensions is considered. Third, the FE component of the solver employs curvilinear tetrahedral elements to precisely model the scatterer's geometry and higher-order vector basis functions to accurately represent the fields.

Dan Jiao - One of the best experts on this subject based on the ideXlab platform.

  • a fast higher order time domain finite element boundary integral Method for 3 d electromagnetic scattering analysis
    IEEE Transactions on Antennas and Propagation, 2002
    Co-Authors: Dan Jiao, Balasubramaniam Shanker, Eric Michielssen, A. Arif Ergin, Jianming Jin
    Abstract:

    A novel hybrid time-domain finite element-boundary integral Method for analyzing three-dimensional (3-D) electromagnetic scattering phenomena is presented. The Method couples finite element and boundary integral field representations in a way that results in a sparse system matrix and solutions that are devoid of spurious modes. To accurately represent the unknown fields, the scheme employs higher-order vector basis functions defined on curvilinear tetrahedral elements. To handle problems involving electrically large objects, the multilevel plane-wave time-domain algorithm is used to accelerate the evaluation of the boundary integrals. Numerical results demonstrate the accuracy and versatility of the proposed scheme.

  • a fast higher order time domain finite element boundary integral Method for 3 d electromagnetic scattering analysis
    IEEE Antennas and Propagation Society International Symposium, 2001
    Co-Authors: Dan Jiao, Balasubramaniam Shanker, Eric Michielssen, A. Arif Ergin, Jianming Jin
    Abstract:

    We present a hybrid time-domain finite element-boundary integral (FE-BI) Method for analyzing 3D electromagnetic open-region transient scattering phenomena. This Method has three unique features. The first is the hybridization scheme that combines the FE and BI representations of the fields. Instead of following the standard hybridization scheme used in the frequency domain, we propose a novel scheme that preserves the sparsity of the finite element matrix and that yields solutions free of spurious modes associated with interior BI resonances. The second feature is the use of a fast algorithm, the multilevel plane-wave time-domain (PWTD) Method, for evaluating the BI. Invoking this scheme greatly reduces the computational expense when an object of large electrical dimensions is considered. Third, the FE component of the solver employs curvilinear tetrahedral elements to precisely model the scatterer's geometry and higher-order vector basis functions to accurately represent the fields.

  • A fast time-domain finite element-boundary integral Method for electromagnetic analysis
    IEEE Transactions on Antennas and Propagation, 2001
    Co-Authors: Dan Jiao, Mingyu Lu, Eric Michielssen
    Abstract:

    A time-domain, finite element-boundary integral (FE-BI) Method is presented for analyzing electromagnetic (EM) scattering from two-dimensional (2-D) inhomogeneous objects. The scheme's finite-element component expands transverse fields in terms of a pair of orthogonal vector basis functions and is coupled to its boundary integral component in such a way that the resultant finite element mass matrix is diagonal, and more importantly, the Method delivers solutions that are free of spurious modes. The boundary integrals are computed using the multilevel plane-wave time-domain algorithm to enable the simulation of large-scale scattering phenomena. Numerical results demonstrate the capabilities and accuracy of the proposed hybrid scheme.

Eric Michielssen - One of the best experts on this subject based on the ideXlab platform.

  • a fast higher order time domain finite element boundary integral Method for 3 d electromagnetic scattering analysis
    IEEE Transactions on Antennas and Propagation, 2002
    Co-Authors: Dan Jiao, Balasubramaniam Shanker, Eric Michielssen, A. Arif Ergin, Jianming Jin
    Abstract:

    A novel hybrid time-domain finite element-boundary integral Method for analyzing three-dimensional (3-D) electromagnetic scattering phenomena is presented. The Method couples finite element and boundary integral field representations in a way that results in a sparse system matrix and solutions that are devoid of spurious modes. To accurately represent the unknown fields, the scheme employs higher-order vector basis functions defined on curvilinear tetrahedral elements. To handle problems involving electrically large objects, the multilevel plane-wave time-domain algorithm is used to accelerate the evaluation of the boundary integrals. Numerical results demonstrate the accuracy and versatility of the proposed scheme.

  • a fast higher order time domain finite element boundary integral Method for 3 d electromagnetic scattering analysis
    IEEE Antennas and Propagation Society International Symposium, 2001
    Co-Authors: Dan Jiao, Balasubramaniam Shanker, Eric Michielssen, A. Arif Ergin, Jianming Jin
    Abstract:

    We present a hybrid time-domain finite element-boundary integral (FE-BI) Method for analyzing 3D electromagnetic open-region transient scattering phenomena. This Method has three unique features. The first is the hybridization scheme that combines the FE and BI representations of the fields. Instead of following the standard hybridization scheme used in the frequency domain, we propose a novel scheme that preserves the sparsity of the finite element matrix and that yields solutions free of spurious modes associated with interior BI resonances. The second feature is the use of a fast algorithm, the multilevel plane-wave time-domain (PWTD) Method, for evaluating the BI. Invoking this scheme greatly reduces the computational expense when an object of large electrical dimensions is considered. Third, the FE component of the solver employs curvilinear tetrahedral elements to precisely model the scatterer's geometry and higher-order vector basis functions to accurately represent the fields.

  • A fast time-domain finite element-boundary integral Method for electromagnetic analysis
    IEEE Transactions on Antennas and Propagation, 2001
    Co-Authors: Dan Jiao, Mingyu Lu, Eric Michielssen
    Abstract:

    A time-domain, finite element-boundary integral (FE-BI) Method is presented for analyzing electromagnetic (EM) scattering from two-dimensional (2-D) inhomogeneous objects. The scheme's finite-element component expands transverse fields in terms of a pair of orthogonal vector basis functions and is coupled to its boundary integral component in such a way that the resultant finite element mass matrix is diagonal, and more importantly, the Method delivers solutions that are free of spurious modes. The boundary integrals are computed using the multilevel plane-wave time-domain algorithm to enable the simulation of large-scale scattering phenomena. Numerical results demonstrate the capabilities and accuracy of the proposed hybrid scheme.

George Biros - One of the best experts on this subject based on the ideXlab platform.

  • dynamic simulation of locally inextensible vesicles suspended in an arbitrary two dimensional domain a boundary integral Method
    Journal of Computational Physics, 2010
    Co-Authors: Abtin Rahimian, Shravan Veerapaneni, George Biros
    Abstract:

    We consider numerical algorithms for the simulation of hydrodynamics of two-dimensional vesicles suspended in a viscous Stokesian fluid. The motion of vesicles is governed by the interplay between hydrodynamic and elastic forces. Continuum models of vesicles use a two-phase fluid system with interfacial forces that include tension (to maintain local ''surface'' inextensibility) and bending. Vesicle flows are challenging to simulate. On the one hand, explicit time-stepping schemes suffer from a severe stability constraint due to the stiffness related to high-order spatial derivatives in the bending term. On the other hand, implicit time-stepping schemes can be expensive because they require the solution of a set of nonlinear equations at each time step. Our Method is an extension of the work of Veerapaneni et al. [S.K. Veerapaneni, D. Gueyffier, D. Zorin, G. Biros, A boundary integral Method for simulating the dynamics of inextensible vesicles suspended in a viscous fluid in 2D, Journal of Computational Physics 228(7) (2009) 2334-2353], in which a semi-implicit time-marching scheme based on a boundary integral formulation of the Stokes problem for vesicles in an unbounded medium was proposed. In this paper, we consider two important generalizations: (i) confined flows within arbitrary-shaped stationary/moving geometries; and (ii) flows in which the interior (to the vesicle) and exterior fluids have different viscosity. In the rest of the paper, we will refer to this as the ''viscosity contrast''. These two problems require solving additional integral equations and cause nontrivial modifications to the previous numerical scheme. Our Method does not have severe time-step stability constraints and its computational cost-per-time-step is comparable to that of an explicit scheme. The discretization is pseudo-spectral in space, and multistep BDF in time. We conduct numerical experiments to investigate the stability, accuracy and the computational cost of the algorithm. Overall, our Method achieves several orders of magnitude speed-up compared to standard explicit schemes. As a preliminary validation of our scheme, we study the dependence of the inclination angle of a single vesicle in shear flow on the viscosity contrast and the reduced area of the vesicle, the lateral migration of vesicles in shear flow, the dispersion of two vesicles, and the effective viscosity of a dilute suspension of vesicles.

  • a boundary integral Method for simulating the dynamics of inextensible vesicles suspended in a viscous fluid in 2d
    Journal of Computational Physics, 2009
    Co-Authors: Shravan Veerapaneni, Denis Gueyffier, Denis Zorin, George Biros
    Abstract:

    We present a new Method for the evolution of inextensible vesicles immersed in a Stokesian fluid. We use a boundary integral formulation for the fluid that results in a set of nonlinear integro-differential equations for the vesicle dynamics. The motion of the vesicles is determined by balancing the non-local hydrodynamic forces with the elastic forces due to bending and tension. Numerical simulations of such vesicle motions are quite challenging. On one hand, explicit time-stepping schemes suffer from a severe stability constraint due to the stiffness related to high-order spatial derivatives and a milder constraint due to a transport-like stability condition. On the other hand, an implicit scheme can be expensive because it requires the solution of a set of nonlinear equations at each time step. We present two semi-implicit schemes that circumvent the severe stability constraints on the time step and whose computational cost per time step is comparable to that of an explicit scheme. We discretize the equations by using a spectral Method in space, and a multistep third-order accurate scheme in time. We use the fast multipole Method (FMM) to efficiently compute vesicle-vesicle interaction forces in a suspension with a large number of vesicles. We report results from numerical experiments that demonstrate the convergence and algorithmic complexity properties of our scheme.

Derek Y C Chan - One of the best experts on this subject based on the ideXlab platform.

  • field only integral equation Method for time domain scattering of electromagnetic pulses
    Applied Optics, 2017
    Co-Authors: Evert Klaseboer, Qiang Sun, Derek Y C Chan
    Abstract:

    The scattering of electromagnetic pulses is described using a non-singular boundary integral Method to solve directly for the field components in the frequency domain, and Fourier transform is then used to obtain the complete space-time behavior. This approach is stable for wavelengths both small and large relative to characteristic length scales. Amplitudes and phases of field values can be obtained accurately on or near material boundaries. Local field enhancement effects due to multiple scattering of interest to applications in microphotonics are demonstrated.

  • space time domain solutions of the wave equation by a non singular boundary integral Method and fourier transform
    arXiv: Computational Physics, 2017
    Co-Authors: Evert Klaseboer, Shahrokh Sepehrirahnama, Derek Y C Chan
    Abstract:

    The general space-time evolution of the scattering of an incident acoustic plane wave pulse by an arbitrary configuration of targets is treated by employing a recently developed non-singular boundary integral Method to solve the Helmholtz equation in the frequency domain from which the fast Fourier transform is used to obtain the full space-time solution of the wave equation. The non-singular boundary integral solution can enforce the radiation boundary condition at infinity exactly and can account for multiple scattering effects at all spacings between scatterers without adverse effects on the numerical precision. More generally, the absence of singular kernels in the non-singular integral equation confers high numerical stability and precision for smaller numbers of degrees of freedom. The use of fast Fourier transform to obtain the time dependence is not constrained to discrete time steps and is particularly efficient for studying the response to different incident pulses by the same configuration of scatterers. The precision that can be attained using a smaller number of Fourier components is also quantified.

  • a robust and non singular formulation of the boundary integral Method for the potential problem
    Engineering Analysis With Boundary Elements, 2014
    Co-Authors: Qiang Sun, Evert Klaseboer, Boo Cheong Khoo, Derek Y C Chan
    Abstract:

    A non-singular formulation of the boundary integral Method (BIM) is presented for the Laplace equation whereby the well-known singularities that arise from the fundamental solution are eliminated analytically. A key advantage of this approach is that numerical errors that arise due to the proximity of nodes located on osculating boundaries are suppressed. This is particularly relevant in multi-scale problems where high accuracy is required without undue increase in computational cost when the spacing between boundaries become much smaller than their characteristic dimensions. The elimination of the singularities means that standard quadrature can be used to evaluate the surface integrals and this results in about 60% savings in coding effort. The new formulation also affords a numerically robust way to calculate the potential close to the boundaries. Detailed implementations of this approach are illustrated with problems involving osculating boundaries, 2D domains with corners and a wave drag problem in a 3D semi-infinite domain. The explicit formulation of problems with axial symmetry is also given.