Comprehensive numerical and experimental analyses of the effect of viscosity on cavitation oscillations are performed. This numerical approach is based on the Rayleigh-Plesset equation. The model predictions are compared with experimental results obtained by using a fibre-optic diagnostic technique based on optical beam deflection (OBD). The maximum and minimum bubble radii as well as the oscillation times for each oscillation cycle are determined according to the characteristic signals. It is observed that the increasing of viscosity decreases the maximum bubble radii but increases the minimum bubble radii and the oscillation time. These experimental results are consistent with numerical results.
A plasma is produced in air by using a high-intensity Q-switch Nd:YAG pulsed laser to irradiate a solid target,and the impulses delivering from the plasma to the target are measured at different laser power densities.Analysing the formation process of laser plasma and the laser supported detonation wave (LSDW) and using fluid mechanics theory and Pirri's methods,an approximately theoretical solution of the impulse delivering from the plasma to the target under our experimental condition is found.Furthermore,according to the formation time of plasma and the variation of pressure in plasma in a non-equilibrium state,a physical model of the interaction between the pulse laser and the solid target is developed.The plasma evolutions with time during and after the laser pulse irradiating the target are simulated numerically by using a three-dimensional difference scheme.And the numerical solutions of the impulse delivering from the plasma to the target are obtained.A comparison among the theoretical,numerical and experimental results and their analyses are performed.The experimental results are explained reasonably.The consistency between numerical results and experimental results implies that the numerical calculation model used in this paper can well describe the mechanical action of the laser on the target.
