Characterization of shear waves in cortical bone using the axial transmission technique

In this paper, the implementation of a moving sound source and receiver with directivity in the three-dimensional finite-difference time-domain (FDTD) method is described. Fundamental solutions of moving monopole, dipole, and cardioid sources are theoretically derived. Some numerical experiments were performed on the three-dimensional sound field for a moving source and receiver. The numerical experiments showed that the effect of moving velocity on amplitude differs for the monopole and dipole or cardioid sources. Furthermore, it was found that directivity characteristics of dipole and cardioid sources vary depending on the beam and moving directions. The present method can be accurately applied to the moving sound source and receiver with directivity.

Section: Introductionmentioning

confidence: 99%

Three-dimensional finite-difference time-domain simulation of moving sound source and receiver with directivity

Tsuchiya¹,

Teshima²,

Hiryu³

2023

“…Among many numerical analysis methods of the sound field, the finite-difference time-domain (FDTD) method [1][2][3][4][5][6][7][8][9][10] is one of the most commonly used tools. In most sound field analysis including the FDTD method, sound sources and receivers are usually fixed, then the responses between them are mainly calculated.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional finite difference-time domain simulation of moving sound source and receiver

Tsuchiya

Teshima

Hiryu

2022

In this paper, moving sound source and receiver with an arbitrary trajectory are implemented in the three-dimensional compact explicit finite-difference time-domain (CE-FDTD) method. To implement a moving sound source, a driving method in which the grid points around the source position are driven by the source distribution function is proposed. It is confirmed that the Gaussian distribution driving is suitable for the analysis of the moving sound sources. For a moving receiver, the sound pressure at the receiver is interpolated from the sound pressures of the adjacent eight grid points. The formulations and the numerical experiments are made for the three-dimensional sound field, and the accuracy of the proposed method is discussed. It is confirmed that the proposed method can be applied accurately to the moving sound source and receiver including the Doppler effect.

“…Various numerical methods such as the finite-difference method, 1) the finite element method, 2) and the boundary element method 3) have been proposed for the sound field analysis. In recent years, the finite-difference time-domain (FDTD) method [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] has been widely used because of its simple algorithm and easy programming. This is a tutorial paper focusing on the FDTD method.…”

Section: Introductionmentioning

confidence: 99%

Recent techniques on sound field simulation

Tsuchiya

2022

This is a tutorial paper on the basics and applications of the finite-difference time-domain (FDTD) method. Two types of discretization of the linear governing equations, the scalar-type FDTD method and the vector-type one, are first discussed. Then the basic concept of the compact explicit-FDTD (CE-FDTD) method is described. By considering the relationship between the cutoff frequency and the computer resources, it is shown that the interpolated wide band scheme requires the least computer resources among the derivative schemes of the CE-FDTD method. The discretization of the arbitrary shaped sound field by voxels and its boundary conditions, and the implementation of the density variation are also described. The sound field rendering and its real time renderer “Silicon concert hall” are introduced.