Numerical study of Love wave propagation

Geophysics ◽  
1983 ◽  
Vol 48 (7) ◽  
pp. 833-853 ◽  
Author(s):  
K. R. Kelly
Keyword(s):  
Numerical Modeling ◽  
Wave Propagation ◽  
Love Wave ◽  
Fourier Transforms ◽  
Narrow Band ◽  
Numerical Study ◽  
Two Dimensional ◽  
Band Pass ◽  
The Waves ◽  
Insight Into

Love wave propagation is studied by investigating numerical modeling results for several examples of geologic interest. The modal characteristics of the results are clarified by the use of narrow band‐pass filters and two‐dimensional Fourier transforms in range and time. Such processing makes it possible to study changes in phase and group velocity for the various modes and to locate points of reflection. This permits one to gain insight into changes in the physical properties of the surface channel supporting the waves.

scholarly journals Numerical Study of Bubble Breakup in Fractal Tree-Shaped Microchannels

2019 ◽  
Vol 20 (21) ◽  
pp. 5516
Author(s):  
Chengbin Zhang ◽  
Xuan Zhang ◽  
Qianwen Li ◽  
Liangyu Wu
Keyword(s):  
Stream Flow ◽  
Numerical Study ◽  
Flow Direction ◽  
Underlying Mechanism ◽  
Two Dimensional ◽  
Bubble Breakup ◽  
Hydrodynamic Behaviors ◽  
Different Levels ◽  
Inlet Capillary ◽  
Insight Into

Hydrodynamic behaviors of bubble stream flow in fractal tree-shaped microchannels is investigated numerically based on a two-dimensional volume of fluid (VOF) method. Bubble breakup is examined in each level of bifurcation and the transition of breakup regimes is discussed in particular. The pressure variations at the center of different levels of bifurcations are analyzed in an effort to gain further insight into the underlying mechanism of bubble breakup affected by multi-levels of bifurcations in tree-shaped microchannel. The results indicate that due to the structure of the fractal tree-shaped microchannel, both lengths of bubbles and local capillary numbers decrease along the microchannel under a constant inlet capillary number. Hence the transition from the obstructed breakup and obstructed-tunnel combined breakup to coalescence breakup is observed when the bubbles are flowing into a higher level of bifurcations. Compared with the breakup of the bubbles in the higher level of bifurcations, the behaviors of bubbles show stronger periodicity in the lower level of bifurcations. Perturbations grow and magnify along the flow direction and the flow field becomes more chaotic at higher level of bifurcations. Besides, the feedback from the unequal downstream pressure to the upstream lower level of bifurcations affects the bubble breakup and enhances the upstream asymmetrical behaviors.

Simulation of Convective Flows in Sinusoidal Partitioned Enclosure

2009 ◽  
Author(s):  
S. H. Anilkumar ◽  
Biju T. Kuzhiveli
Keyword(s):  
Numerical Study ◽  
Valuable Insight ◽  
Two Dimensional ◽  
Flow And Heat Transfer ◽  
Aspect Ratios ◽  
Experimental Works ◽  
Isothermal Wall ◽  
Oriented Parallel ◽  
Rayleigh Numbers ◽  
Insight Into

A numerical study is carried out for natural convective flow and heat transfer in a two-dimensional enclosure with centrally located sinusoidal thin partition for a range of Rayleigh numbers, partition heights and aspect ratios. The partition is oriented parallel to the two vertical isothermal walls and the other surfaces are insulated. The flow and temperature distributions are taken to be two-dimensional. Transport equations are modeled by a stream function-vorticity formulation and are solved numerically by finite-difference approach. Comparisons with previously published numerical and experimental works are done and found to be in excellent agreement. The Rayleigh number varies from 103 to 106 and aspect ratio from 0.5 to 5. The results are presented for different fluids in the form of streamlines, vectors and isotherm plots. The variation of local Nusselt number over the sinusoidal partition and isothermal wall provide valuable insight into the physical processes.

scholarly journals Studi Penjalaran Gelombang Laut di Pulau Panjang, Kabupaten Jepara

2021 ◽  
Vol 10 (1) ◽  
pp. 75-87
Author(s):  
Tri Widya Laksana Putra ◽  
Muhammad Zainuri ◽  
Denny Nugroho Sugianto
Keyword(s):  
Wave Propagation ◽  
Direct Measurement ◽  
Hydrodynamic Model ◽  
High Tide ◽  
Acoustic Doppler Current Profiler ◽  
Wind Data ◽  
Two Dimensional ◽  
Single Beam ◽  
Current Profiler ◽  
The Waves

Pulau Panjang terletak di sebelah barat pantai Kota Jepara memiliki luas wilayah teritorial 30 Ha dan dimanfaatan sebagai wisata pulau, wisata ziarah, dan lokasi penangkapan ikan. Kombinasi kondisi gelombang ekstrim dan air pasang mengakibatkan tekanan kuat di pesisir Pulau Panjang sehingga menimbulkan kerusakan pada fasilitas wisata. Berdasarkan hal tersebut, diperlukan adanya analisis mengenai karakteristik penjalaran gelombang laut untuk menunjang segala jenis kegiatan masyarakat. Analisis penjalaran gelombang dilakukan melalui pendekatan pemodelan numerik hidrodinamika dua dimensi (two-dimensional hydrodynamic model). Data primer yang digunakan adalah data pengukuran langsung nilai gelombang menggunakan instrument Acoustic Doppler Current Profiler dan pengukuran langsung data batimetri menggunakan instrument single-beam echosounder. Data sekunder meliputi data angin (1999 – 2019) yang didapatkan dari portal unduh data di www.ogimet.com, data pasang surut BMKG dan data batimetri dari Badan Informasi Geospasial. Tinggi gelombang signifikan (Hs) dan periode signifikan (Ts) didapatkan dari konversi data angin menjadi nilai Hs dan Ts dengan metode DNS. Nilai Hs dan Ts maksimal setiap arah mata angin mmenjadi input perhitungan model hidrdodinamika. Hasil spasial penjalaran gelombang tertinggi terjadi pada arah datang gelombang dari arah timur laut, tenggara dan barat.  Penjalaran gelombang di Pulau Panjang menciptakan daerah terlindung di sisi seberang dari arah datang gelombang dan saat gelombang endekati pantai penjalaran gelombang mengikuti kontur garis pantai diikuti dengan melemahnya kecepatan rambat gelombang. Panjang Island is located on the west coast of Jepara City and has a territorial area of 30 hectares and is used as island tourism, pilgrimage tours, and fishing locations. The combination of extreme wave conditions and high tide resulted in strong force on the coast of Panjang Island causing damage to tourist facilities. Based on this, it is necessary to have an characteristics analysis of the sea waves propagation to support all types of community activities. Analysis of the propagation of the waves was carried out using a two-dimensional hydrodynamic model approach. The primary data used are direct measurement data of wave values using the Acoustic Doppler Current Profiler instrument and direct measurement of bathymetric data using a single-beam echosounder instrument. Secondary data includes wind data (1999 - 2019) obtained from the data download portal at www.ogimet.com, BMKG tidal data and bathymetry data from the Geospatial Information Agency. Significant wave height (Hs) and significant period (Ts) are obtained from the conversion of wind data into Hs and Ts values using the DNS method. The maximum Hs and Ts values for each cardinal direction are the input for calculating the hydrodynamic model. The highest spatial results of wave propagation occur in the coming direction of waves from the northeast, southeast and west. The wave propagation in Panjang Island creates a protected area on the opposite side from the direction of the waves coming and when the waves approach the coast the propagation of the waves follow the contours of the coastline followed by a weakening of the wave propagation speed.

Love-wave propagation in a three-dimensional sedimentary basin

1992 ◽  
Vol 82 (4) ◽  
pp. 1661-1677 ◽  
Author(s):  
Takumi Toshinawa ◽  
Tatsuo Ohmachi
Keyword(s):  
Finite Element ◽  
Wave Propagation ◽  
Love Wave ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Sedimentary Basins ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Time Histories

Abstract A simplified three-dimensional finite-element method has been developed for simulation of Love-wave propagation in three-dimensional sedimentary basins. The eigenfunctions for the fundamental-mode surface waves are employed as interpolation functions in the finite-element scheme. By reducing the number of degrees of freedom, the method enables us to analyze wave propagation in an area of 2000 km2 as large as the southern part of the Kanto plain, Japan. Time histories of the near Izu-Ohshima earthquake of 1990 are calculated and compared with observation. Calculated displacement snapshots show the effect of three-dimensional topography on direction of Love-wave propagation. The three-dimensional simulation is also compared with a two-dimensional one, demonstrating amplitude increase and extended duration. Time histories and their spectra from the three-dimensional model show better agreement with the observations than those from the two-dimensional model.

Spurious multiples in seismic interferometry of primaries

Geophysics ◽  
2006 ◽  
Vol 71 (4) ◽  
pp. SI111-SI124 ◽  
Author(s):  
Roel Snieder ◽  
Kees Wapenaar ◽  
Ken Larner
Keyword(s):  
Wave Propagation ◽  
Free Surface ◽  
Homogeneous Medium ◽  
Physical Principle ◽  
Seismic Interferometry ◽  
Heuristic Argument ◽  
Direct Wave ◽  
Reflected Waves ◽  
The Waves ◽  
Insight Into

Seismic interferometry is a technique for estimating the Green’s function that accounts for wave propagation between receivers by correlating the waves recorded at these receivers. We present a derivation of this principle based on the method of stationary phase. Although this derivation is intended to be educational, applicable to simple media only, it provides insight into the physical principle of seismic interferometry. In a homogeneous medium with one horizontal reflector and without a free surface, the correlation of the waves recorded at two receivers correctly gives both the direct wave and the singly reflected waves. When more reflectors are present, a product of the singly reflected waves occurs in the crosscorrelation that leads to spurious multiples when the waves are excited at the surface only. We give a heuristic argument that these spurious multiples disappear when sources below the reflectors are included. We also extend the derivation to a smoothly varying heterogeneous background medium.

Properties of electromagnetic waves in ferrites

1985 ◽  
Vol 399 (1817) ◽  
pp. 217-241 ◽  
Keyword(s):  
Refractive Index ◽  
Wave Equation ◽  
Electromagnetic Waves ◽  
Permeability Tensor ◽  
Underlying Structure ◽  
Two Dimensional ◽  
Systematic Account ◽  
Dimensional Parameter ◽  
The Waves ◽  
Insight Into

In this paper we present a derivation of the general wave equation governing the propagation of electromagnetic waves in ferrites. This is shown to be equivalent to the usual Helmholtz form obtained by introducing a permeability tensor. Its real underlying structure is somewhat obscured by the Helmholtz form because in this form the time dependence is submerged in the frequency-dependent elements of the permeability tensor. However, the main purpose of the paper is to provide a systematic account of the properties of electromagnetic waves in ferrites and this is done by making use of the close analogy that exists between wave propagation in ferrites and that in cold magnetized plasmas. This facilitates the construction of a so-called ‘C. M. A. diagram’ for a ferrite, which classifies the waves according to the various topologies of the refractive index and ray surfaces (along with the associated wave polarizations) in a two-dimensional parameter space that relates the wave frequency to the precessional frequencies intrinsic to the magnetization of the ferrite. The insight into the behaviour of waves in ferrites that this approach provides is illustrated in connection with the phenomena of cut-offs, resonances and wave-focusing, which give rise to caustics.

Wave Propagation Feature in Two-Dimensional Periodic Beam Lattices with Local Resonance by Numerical Method and Analytical Homogenization Approach

2018 ◽  
Vol 10 (04) ◽  
pp. 1850042 ◽  
Author(s):  
C. W. Zhou ◽  
X. K. Sun ◽  
J. P. Lainé ◽  
M. N. Ichchou ◽  
A. Zine ◽  
...  
Keyword(s):  
Wave Propagation ◽  
Homogenization Method ◽  
Two Dimensional ◽  
Local Resonance ◽  
Homogenization Approach ◽  
Discrete Media ◽  
The Waves ◽  
Locking Phenomena ◽  
Analytical Homogenization ◽  
Propagation Feature

In this paper, the analytical homogenization method of Periodic Discrete Media (HPDM) and the numerical Condensed Wave Finite Element Method (CWFEM) are employed to study the wave propagation in two-dimensional periodic beam lattices. The validity of the HPDM is re-evaluated using the wave propagation feature identified by the CWFEM. Particular attention is paid to the polarization direction of the waves. The wave propagation in two directions is investigated while characteristic wave propagation features such as local resonance, veering and locking phenomena are observed. Complementary results are deduced from the two methods.

Slowly decaying drift turbulence with wave effects

1999 ◽  
Vol 61 (4) ◽  
pp. 601-622 ◽  
Author(s):  
GIOVANNI MANFREDI
Keyword(s):  
Wave Propagation ◽  
Mode Coupling ◽  
Narrow Band ◽  
Perpendicular Direction ◽  
Nonlinear Interactions ◽  
Linear Waves ◽  
Wave Effects ◽  
Geostrophic Turbulence ◽  
Nonlinear Mode Coupling ◽  
The Waves

The effect of linear waves on the Charney–Hasegawa–Mima model of drift and geostrophic turbulence is studied numerically for a slowly decaying field. It is shown that wave effects can reduce the efficiency of nonlinear mode coupling, effectively ‘freezing’ the spectrum to a narrow band in wavenumber space. Selective nonlinear interactions tend to favour velocities parallel to the direction of propagation of the waves. Accordingly, anisotropic spectra are observed, steeper in the direction of wave propagation, and shallower in the perpendicular direction.

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