scholarly journals Time domain room acoustic simulations using the spectral element method

2019 ◽  
Vol 145 (6) ◽  
pp. 3299-3310 ◽  
Author(s):  
Finnur Pind ◽  
Allan P. Engsig-Karup ◽  
Cheol-Ho Jeong ◽  
Jan S. Hesthaven ◽  
Mikael S. Mejling ◽  
...  
Keyword(s):  
Time Domain ◽  
Spectral Element Method ◽  
Spectral Element ◽  
Element Method

scholarly journals An axisymmetric time-domain spectral-element method for full-wave simulations: Application to ocean acoustics

2016 ◽  
Vol 140 (5) ◽  
pp. 3520-3530 ◽  
Author(s):  
Alexis Bottero ◽  
Paul Cristini ◽  
Dimitri Komatitsch ◽  
Mark Asch
Keyword(s):  
Time Domain ◽  
Spectral Element Method ◽  
Spectral Element ◽  
Ocean Acoustics ◽  
Full Wave ◽  
Element Method

scholarly journals Removing the CFL stability criterion of the explicit time-domain very high degree spectral-element method with eigenvalue perturbation

Geophysics ◽  
2021 ◽  
pp. 1-29
Author(s):  
Chao Lyu ◽  
Yann Capdeville ◽  
Gang Lv ◽  
Liang Zhao
Keyword(s):  
Time Domain ◽  
Stability Criterion ◽  
Spectral Element Method ◽  
Waveform Inversion ◽  
Spectral Element ◽  
Time Step ◽  
Transform Method ◽  
Time Dispersion ◽  
The Stability ◽  
Element Method

The explicit time-domain spectral-element method (SEM) for synthesizing seismograms hasgained tremendous credibility within the seismological community at all scales. Althoughthe recent introduction of non-periodic homogenization has addressed the spatial meshing difficulty of the mechanical discontinuities, the Courant-Friedrichs-Lewy (CFL) stability criterionstrictly constrains the maximum time step, which still puts a great burden on the numericalsimulation. In the explicit time-domain SEM, the source of instability of using a time stepbeyond the stability criterion is that some unstable eigenvalues of the updated matrix are largerthan what can be accurately simulated. We succeed in removing the CFL stability condition inthe explicit time-domain SEM by combining the forward time dispersion-transform method,the eigenvalue perturbation, and the inverse time dispersion-transform method. Our theoretical analyses and numerical experiments both in the homogeneous, moderate and strong heterogeneous models, show that this combination can precisely simulate waveforms with timesteps dozens of the CFL limit even towards the Nyquist limit especially for the efficient veryhigh degree SEM, which abundantly saves the iteration times without suffering from the time-dispersion error. It demonstrates a potential application prospect in some situations such as thefull waveform inversion which requires multiple numerical simulations for the same model.

Wave transmission characteristics for higher-order sandwich panel with flexible core using time-domain spectral element method

2016 ◽  
Vol 19 (3) ◽  
pp. 364-393 ◽  
Author(s):  
B Raja Sekhar ◽  
S Gopalakrishnan ◽  
MVVS Murthy
Keyword(s):  
Wave Propagation ◽  
Time Domain ◽  
Spectral Element Method ◽  
Sandwich Panel ◽  
Spectral Element ◽  
Free Vibrations ◽  
Higher Order ◽  
Frequency Wave ◽  
Beam Design ◽  
Element Method

A new time-domain spectral element with nine degrees of freedom per node is formulated based on higher-order sandwich panel theory, incorporating the flexible behaviour of the core with composite face sheets. Static, free vibrations and wave propagation analysis are carried out using the formulated element. Results obtained using this element are compared with those available in the literature and with commercial finite element codes. The fast convergence of the spectral element method is demonstrated by solving the high-frequency wave propagation problem. A method of computing the wave characteristics, namely wavenumbers and group velocities, in a higher-order sandwich panel is developed using the formulated element. The effect of core damping is studied in detail with different core types, which can be used effectively in sandwich beam design.

Efficient time-domain 3D elastic and viscoelastic full-waveform inversion using a spectral-element method on flexible Cartesian-based mesh

Geophysics ◽  
2019 ◽  
Vol 84 (1) ◽  
pp. R61-R83 ◽  
Author(s):  
Phuong-Thu Trinh ◽  
Romain Brossier ◽  
Ludovic Métivier ◽  
Laure Tavard ◽  
Jean Virieux
Keyword(s):  
Time Domain ◽  
Spectral Element Method ◽  
Waveform Inversion ◽  
Spectral Element ◽  
Body Waves ◽  
P Wave ◽  
Full Waveform Inversion ◽  
Full Waveform ◽  
Anisotropic Elastic ◽  
Element Method

Viscoelastic full-waveform inversion is recognized as a challenging task for current acquisition deployment at the crustal scale. We have developed an efficient formulation based on a time-domain spectral-element method on a flexible Cartesian-based mesh. We consider anisotropic elastic coefficients and isotropic attenuation. Complete gradient expressions including the attenuation contribution spread into those of elastic components are given in a consistent way. The influence of attenuation on the P-wave velocity reconstruction is illustrated through a toy configuration. The numerical implementation of the forward problem includes efficient matrix-vector products for solving second-order elastodynamic equations for 3D geometries: An original high-order integration for topography effects is performed at nearly no extra cost. Combined adjoint and forward field recomputation from the final state and previously saved boundary values allows the estimation of misfit gradients for density, elastic parameters, and attenuation factors with no I/O efforts. Two-level parallelism is implemented over the sources and domain decomposition, which is necessary for a realistic 3D configuration. The misfit gradient preconditioning is performed by a so-called Bessel filter using an efficient differential implementation based on finite-element ingredients on the forward mesh instead of the often-used, costly convolution approach. A 3D synthetic illustration is provided on a subset ([Formula: see text]) of the SEG Advanced Modeling (SEAM) Phase II Foothills model with 4 lines of 20 sources. The structurally based Bessel filter and a simple data hierarchy strategy considering early body waves before all waves including surface waves allow a precise reconstruction of the P- and S-wavespeeds while keeping a smooth density description.

Sign in / Sign up

Export Citation Format

Share Document