Low-Reynolds-number flow of a second-order fluid past a porous sphere

The conversion of energy from a laser-generated heat pulse to an acoustic wave in a liquid is considered in detail. In particular, the development of finite and large amplitude pressure waves is treated with the help of a table of state functions for the liquid. Optical saturation is included in the numerical computation and shown to produce increased depth of heating in the dye. Saturation generally decreases the peak pressure and increases the pulse width. An exception is the case when the optical wave saturates the dye and penetrates it with a velocity near Mach one. In this case, pressure amplitude grows with increasing laser pulse penetration. Calculations are carried out for plane, cylindrical, and spherical geometries. Experimental comparisons with calculations are made for the free-surface boundary condition and there is a good agreement.