Pol Grasland-Mongrain edited Simu disp maps.tex  over 8 years ago

Commit id: e96ae1434acf0b10e4ba180cc011a503cd78fb61

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  This physical phenomenon was then modeled numerically. The vaporization was modeled as a point force directed along Z direction with a depth of 50 $\mu$m and increasing linearly from -2.5 to 0 mm and decreasing symmetrically from 0 to 2.5 mm, to simulate an approximate Gaussian shape. Propagation as a shear wave was calculated using Green operators $G_y$ and $G_z$ as calculated by Aki Richards \cite{aki1980quantitative}:  \begin{equation}  G_z G_y  = \frac{\cos^2 \frac{\cos \beta \sin  \beta}{4\pi \rho c_p^2 r} \delta_P + \frac{\sin^2 \frac{-\sin \beta \cos  \beta}{4\pi \rho c_s^2 r} \delta_S + \frac{3\cos^2 \beta-1}{4\pi \frac{3\cos \beta \sin \beta}{4\pi  \rho r^3} \tau Rect \\ Rect\\  G_y G_z  = \frac{\cos \beta \sin \frac{\cos^2  \beta}{4\pi \rho c_p^2 r} \delta_P + \frac{-\sin \beta \cos \frac{\sin^2  \beta}{4\pi \rho c_s^2 r} \delta_S + \frac{3\cos \beta \sin \beta}{4\pi \frac{3\cos^2 \beta-1}{4\pi  \rho r^3} \tau Rect \\  \label{eq:akirichards}  \end{equation}  where $\beta$ is the angle between the applied force and the axis y or z, $\rho$ the medium density, $c_p$ and $c_s$ the compression and shear wave speed respectively, $\delta_S$ and $\delta_P$ Dirac distribution indicating the position of the compression and shear waves along space and time, $\tau$ the time and $Rect$ the near-field term. The three terms correspond respectively to the far-field compression wave, the far-field shear wave and the near-field term.