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Center for Nonlinear Studies |
We suggest a new rezoning technique for ALE simulations, based on decomposition of mesh movement into simple deformation modes, represented by an orthogonal set of base vectors. Arbitrary Lagrangian-Eulerian (ALE) methods are widely used to simulate problems involving large deformations and volume changes of the computational domain, typically in shock hydrodynamics or plasma physics. To maintain a sufficient precision during the whole computation, it is critical to have a robust general method for mesh rezoning (adaptation), which is able to recognize and remove unphysical mesh distortions. Despite continuous development in the course of last 30 years, none of the methods presented so far is completely satisfactory and sufficiently general. To address this problem, we construct a physically motivated and mathematically rigorous approach to modal decomposition of discrete fluid flows. This is done by expressing mesh movement as a linear combination of simple, synoptic modes such as translation, rotation, inflation and deviatoric strains. Subsequently, we can filter or damp the components causing high-frequency mesh distortion, while preserving the low-frequency deformation which contains valuable information about physical behavior of the simulated system. The final objective of this project is to develop a new general mesh rezoning strategy for ALE simulation codes which are currently under development at LANL as well as at CTU. Although testing and tuning of the method in real physical applications is still under way, promising preliminary results will be presented.
Host: T-07