No abstract

No abstract

A 3D numerical study of the turbulent phase of the evolution of Rayleigh–Taylor instability (RTI) was undertaken using the MAH-3 code. A criterion and a technique have been developed that can be used for diagnostics in computational experiments studying flow transition to self-similar turbulence. It has been found that a criterion of the flow transition to the self-similar turbulence is Kolmogorov's self-similar distribution of the turbulent kinetic energy together with the square law of mixing zone extension. The technique is based on the analysis of the evolution of the dimensionless power spectrum of specific kinetic energy. Three phases of nonlinear mixing are found: “relict chaos”, “formation of classical energy spectrum” and “spectrum degradation.” Determination of a proportionality factor for a square law within the time range incorporating inertial interval gives the value of α ≈ 0.07.

No abstract

Significant progress has been achieved over the last decade in the realistic animation of garments. However it is still a very costly process in terms of computational resources. Since wrinkles and vast smooth areas co-exist commonly, it is tempting to reduce computational cost by avoiding redundant tessellation at the smooth areas. In this paper we present a method for dynamic adaptation of triangular meshes suitable for the most elaborated cloth simulation approaches, such as finite-element based or alike. We use bottom-up approach to mesh refinement, which does not require precomputation and storage of multiresolution hierarchy. The hierarchy is constructed in runtime using √3-refinement rule. The hierarchy is essential to allow reverting of the refinement locally. Local mesh refinement and simplification are triggered by curvature-induced criterion, where the curvature is estimated using methods of discrete differential geometry. In the existing literature of adaptive meshes only the formulas for estimating the discrete mean curvature at the inner mesh vertices can be found. We extend it to the triangulated 2-manifolds with boundary, such as cloth meshes. The results demonstrated are the realistic animation of garment worn by a walking mannequin generated with Baraff-Witkin type cloth solver enhanced with our mesh adaptation scheme.