A Surface Flow Approach for Predicting Crosshatch Patterns

An analytical model based on liquid layer stability theory is used to predict the stability characteristics and geometric features of crosshatched ablation patterns. This approach postulates the formation of a melt or viscoelastic layer which interacts with the gas boundary layer. For supersonic flow, the dominant amplifying effect is found to be the component of the gas pressure perturbation acting in the valleys of the surface waves, while the dominant damping effect is the component of the gas shear perturbation acting on the wave slope. Solutions for the rate of amplification yield parameters that characterize pattern onset, wave angle, wavelength, and depth. Correlations with experimental data show reasonably good agreement. p g h Km M p Pmag Re t T UL x,y,z XN a p y F 6 5L e