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

Commit id: 2244b47e16ad5c8669643811c7c1ee25e9d01a3e

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If enough energy is deposited, the local increase of temperature could also vaporize a part of the surface of the medium \cite{scruby1990laser}. Using an energy of 200 mJ in equation \ref{eq:eqChaleurApprox}, with same experimental parameters as before, we find a maximum increase of temperature of 60 K, which is close to the vaporization point of our medium, that we could approximate in a first hypothesis as 373K (water vaporization temperature). Besides the uncertainty of some values, it has been demonstrated that the presence of small particles like the graphite particles in our medium acts as nucleation sites for vaporization, which facilitate the vaporization of the medium at lower temperature \cite{Alimpiev_1995}: the energy can in reality be sufficient to get a "vaporization" regime.  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 $G_zz$ $G_{zz}$  \cite{aki1980quantitative}: \begin{equation}  G_{zz}(r,\theta,z) = \frac{\cos^2 \theta}{4\pi \rho c_p^2 r} \delta_P + \frac{\sin^2 \theta}{4\pi \rho c_s^2 r} \delta_S + \frac{3\cos^2 \theta-1}{4\pi \rho r^3} \int_{r/c_p}^{r/c_s}{\tau \delta_{NF}}  \label{eq:Gzz}