Accession Number : ADA326280

Title :   Fully Threaded Tree for Adaptive Refinement Fluid Dynamics Simulations,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC

Personal Author(s) : Khokhlov, A. M.

PDF Url : ADA326280

Report Date : 30 MAY 1997

Pagination or Media Count : 41

Abstract : A fully threaded tree (FTT) for adaptive refinement of regular meshes is described. By using a tree threaded at all levels, tree traversals for finding nearest neighbors are avoided. All operations on a tree including tree modifications are O(N), where N is a number of cells, and are performed in parallel. An efficient implementation of the tree is described that requires 2N words of memory. A filtering algorithm for removing high frequency noise during mesh refinement is described. A FTT can be used in various numerical applications. In this paper, it is applied to the integration of the Euler equations of fluid dynamics. An adaptive mesh time stepping algorithm is described in which different time steps are used at different levels of the tree. Time stepping and mesh refinement are interleaved to avoid extensive buffer layers of fine mesh which were otherwise required ahead of moving shocks. Test examples are presented, and the FTT performance is evaluated. The three dimensional simulation of the interaction of a shock wave and a spherical bubble is carried out that shows the development of azimuthal perturbations on the bubble surface.

Descriptors :   *FINITE ELEMENT ANALYSIS, *FLUID DYNAMICS, ALGORITHMS, SHOCK WAVES, THREE DIMENSIONAL, TOPOLOGY, BUBBLES, ADAPTIVE SYSTEMS, FAST FOURIER TRANSFORMS, EULER EQUATIONS, NUMERICAL METHODS AND PROCEDURES.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE