3-DIMENSIONAL SIMULATIONS AND ANALYSIS OF THE NONLINEAR STAGE OF THE RAYLEIGH-TAYLOR INSTABILITY

The nonlinear stage in the growth of the Rayleigh-Taylor instability i n three dimensions (3D) is studied using a 3D multimaterial hydrodynam ic code. The growth of a single classical 3D square and rectangular mo des is compared to the growth in planar and cylindrical geometries and found to be close to the corresponding cylindrical mode, which is in agreement with a new Layzer-type model for 3D bubble growth. The Atwoo d number effect on the final shape of the instability is demonstrated. Calculations in spherical geometry of the late deceleration stage of a typical ICF pellet have been performed. The different late-time shap es obtained are shown to be a result of the initial conditions and the high Atwood number. Finally, preliminary results of calculations of t wo-mode coupling and random perturbations growth in 3D are presented.