The Experts below are selected from a list of 1680 Experts worldwide ranked by ideXlab platform
Chongmin Song - One of the best experts on this subject based on the ideXlab platform.
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The computation of dispersion relations for Axisymmetric waveguides using the Scaled Boundary Finite Element Method.
Ultrasonics, 2014Co-Authors: Hauke Gravenkamp, Carolin Birk, Chongmin SongAbstract:This paper addresses the computation of dispersion curves and mode shapes of elastic guided waves in Axisymmetric waveguides. The approach is based on a Scaled Boundary Finite Element formulation, that has previously been presented for plate structures and general three-dimensional waveguides with complex cross-section. The formulation leads to a Hamiltonian eigenvalue problem for the computation of wavenumbers and displacement amplitudes, that can be solved very efficiently. In the Axisymmetric Representation, only the radial direction in a cylindrical coordinate system has to be discretized, while the circumferential direction as well as the direction of propagation are described analytically. It is demonstrated, how the computational costs can drastically be reduced by employing spectral elements of extremely high order. Additionally, an alternative formulation is presented, that leads to real coefficient matrices. It is discussed, how these two approaches affect the computational efficiency, depending on the elasticity matrix. In the case of solid cylinders, the singularity of the governing equations that occurs in the center of the cross-section is avoided by changing the quadrature scheme. Numerical examples show the applicability of the approach to homogeneous as well as layered structures with isotropic or anisotropic material behavior.
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On the computation of dispersion curves for Axisymmetric elastic waveguides using the Scaled Boundary Finite Element Method
Computers & Structures, 2014Co-Authors: Hauke Gravenkamp, Fabian Bause, Chongmin SongAbstract:In this paper we propose an algorithm to compute specific parts of the dispersion curves for elastic waveguides. The formulation is based on an Axisymmetric Representation of the Scaled Boundary Finite Element Method, where the wavenumbers of propagating modes are obtained as solutions of a Hamiltonian eigenvalue problem. The novel solution procedure involves tracing selected modes over a given frequency range and computing the corresponding solutions by means of inverse iteration. The resulting algorithm is applied in the context of material characterization, where the efficiency of the computation is crucial.
Hauke Gravenkamp - One of the best experts on this subject based on the ideXlab platform.
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The computation of dispersion relations for Axisymmetric waveguides using the Scaled Boundary Finite Element Method.
Ultrasonics, 2014Co-Authors: Hauke Gravenkamp, Carolin Birk, Chongmin SongAbstract:This paper addresses the computation of dispersion curves and mode shapes of elastic guided waves in Axisymmetric waveguides. The approach is based on a Scaled Boundary Finite Element formulation, that has previously been presented for plate structures and general three-dimensional waveguides with complex cross-section. The formulation leads to a Hamiltonian eigenvalue problem for the computation of wavenumbers and displacement amplitudes, that can be solved very efficiently. In the Axisymmetric Representation, only the radial direction in a cylindrical coordinate system has to be discretized, while the circumferential direction as well as the direction of propagation are described analytically. It is demonstrated, how the computational costs can drastically be reduced by employing spectral elements of extremely high order. Additionally, an alternative formulation is presented, that leads to real coefficient matrices. It is discussed, how these two approaches affect the computational efficiency, depending on the elasticity matrix. In the case of solid cylinders, the singularity of the governing equations that occurs in the center of the cross-section is avoided by changing the quadrature scheme. Numerical examples show the applicability of the approach to homogeneous as well as layered structures with isotropic or anisotropic material behavior.
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On the computation of dispersion curves for Axisymmetric elastic waveguides using the Scaled Boundary Finite Element Method
Computers & Structures, 2014Co-Authors: Hauke Gravenkamp, Fabian Bause, Chongmin SongAbstract:In this paper we propose an algorithm to compute specific parts of the dispersion curves for elastic waveguides. The formulation is based on an Axisymmetric Representation of the Scaled Boundary Finite Element Method, where the wavenumbers of propagating modes are obtained as solutions of a Hamiltonian eigenvalue problem. The novel solution procedure involves tracing selected modes over a given frequency range and computing the corresponding solutions by means of inverse iteration. The resulting algorithm is applied in the context of material characterization, where the efficiency of the computation is crucial.
Carolin Birk - One of the best experts on this subject based on the ideXlab platform.
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The computation of dispersion relations for Axisymmetric waveguides using the Scaled Boundary Finite Element Method.
Ultrasonics, 2014Co-Authors: Hauke Gravenkamp, Carolin Birk, Chongmin SongAbstract:This paper addresses the computation of dispersion curves and mode shapes of elastic guided waves in Axisymmetric waveguides. The approach is based on a Scaled Boundary Finite Element formulation, that has previously been presented for plate structures and general three-dimensional waveguides with complex cross-section. The formulation leads to a Hamiltonian eigenvalue problem for the computation of wavenumbers and displacement amplitudes, that can be solved very efficiently. In the Axisymmetric Representation, only the radial direction in a cylindrical coordinate system has to be discretized, while the circumferential direction as well as the direction of propagation are described analytically. It is demonstrated, how the computational costs can drastically be reduced by employing spectral elements of extremely high order. Additionally, an alternative formulation is presented, that leads to real coefficient matrices. It is discussed, how these two approaches affect the computational efficiency, depending on the elasticity matrix. In the case of solid cylinders, the singularity of the governing equations that occurs in the center of the cross-section is avoided by changing the quadrature scheme. Numerical examples show the applicability of the approach to homogeneous as well as layered structures with isotropic or anisotropic material behavior.
Fabian Bause - One of the best experts on this subject based on the ideXlab platform.
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On the computation of dispersion curves for Axisymmetric elastic waveguides using the Scaled Boundary Finite Element Method
Computers & Structures, 2014Co-Authors: Hauke Gravenkamp, Fabian Bause, Chongmin SongAbstract:In this paper we propose an algorithm to compute specific parts of the dispersion curves for elastic waveguides. The formulation is based on an Axisymmetric Representation of the Scaled Boundary Finite Element Method, where the wavenumbers of propagating modes are obtained as solutions of a Hamiltonian eigenvalue problem. The novel solution procedure involves tracing selected modes over a given frequency range and computing the corresponding solutions by means of inverse iteration. The resulting algorithm is applied in the context of material characterization, where the efficiency of the computation is crucial.
Leigh A. Stearns - One of the best experts on this subject based on the ideXlab platform.
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Near-glacier surveying of a subglacial discharge plume: implications for plume parameterizations†
Geophysical Research Letters, 2017Co-Authors: Rebecca H. Jackson, Emily L. Shroyer, Jonathan D. Nash, David A. Sutherland, Dustin Carroll, M. Fried, Ginny A. Catania, Timothy C. Bartholomaus, Leigh A. StearnsAbstract:At tidewater glaciers, plume dynamics affect submarine melting, fjord circulation, and the mixing of meltwater. Models often rely on buoyant plume theory to parameterize plumes and submarine melting; however, these parameterizations are largely untested due to a dearth of near-glacier measurements. Here, we present a high-resolution ocean survey by ship and remotely-operated boat near the terminus of Kangerlussuup Sermia in west Greenland. These novel observations reveal the 3D structure and transport of a near-surface plume, originating at a large undercut conduit in the glacier terminus, that is inconsistent with Axisymmetric plume theory, the most common Representation of plumes in ocean-glacier models. Instead, the observations suggest a wider upwelling plume – a ‘truncated’ line plume of ∼200 m width – with higher entrainment and plume-driven melt compared to the typical Axisymmetric Representation. Our results highlight the importance of a subglacial outlet's geometry in controlling plume dynamics, with implications for parameterizing the exchange flow and submarine melt in glacial fjord models.