THE EFFECT OF VISCOSITY IN HYPERVELOCITY IMPACT CRATERING

摘要

A numerical method, of second order in both time and space, for the solution of the time-dependent compressible Navier-Stokes equations is presented. Conditions for stability are discussed. The method has been applied to calculate an axisymmetric flow field produced by hypervelocity impact. Results are given for impacts of aluminum cylinders (having diameters of 0.16, 0.32, and 0.64 cm) into aluminum targets. Viscosities of zero and 10~4 poise were assumed. Both plates and semi-infinite targets are considered at an impact speed of 10 km/sec. It is concluded that viscous effects become increasingly important as projectile size diminishes and cannot be neglected during the initial stages of crater formation for projectiles smaller than O.S cm in diameter.