Accession Number : ADA297454

Title :   The Dependence of the Time-Asymptotic Structure of 3-D Vortex Breakdown on Boundary and Initial Conditions.

Descriptive Note : Doctoral thesis,

Corporate Author : AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH

Personal Author(s) : Tromp, Jeffrey C.

PDF Url : ADA297454

Report Date : JUL 1995

Pagination or Media Count : 251

Abstract : The three-dimensional, compressible Navier-Stokes equations are solved numerically to simulate vortex breakdown in tubes. Time integration is performed with an implicit Beam-Warming algorithm, which uses fourth-order compact operators to discretize spatial derivatives. Initial conditions are obtained by solving the steady, compressible, and axisymmetric form of the Navier-Stokes equations using Newton's method. Stability of the axisymmetric initial conditions is assessed through 3-D time integration. Unique axisymmetric solutions at a Reynolds number of 250 lose stability to 3-D disturbances at a critical value of vortex strength, resulting in 3-D and time-periodic flow. Axisymmetric solutions at a Reynolds number of 1000 contain regions of nonuniqueness. Within this region, 3-D time integration reveals only unique solutions, with nonunique, axisymmetric initial conditions converging to a unique solution that is steady and axisymmetric. Past the primary limit point, which approximately identifies critical flow, the solutions bifurcate into 3-D periodic flows.

Descriptors :   *VORTICES, *COMPUTATIONAL FLUID DYNAMICS, *COMPRESSIBLE FLOW, *NAVIER STOKES EQUATIONS, MATHEMATICAL MODELS, ALGORITHMS, STABILITY, EQUATIONS OF MOTION, TIME DEPENDENCE, GRIDS, THESES, FLOW VISUALIZATION, SOLUTIONS(GENERAL), NUMERICAL INTEGRATION, SUPERCRITICAL FLOW, OPERATORS(MATHEMATICS), MACH NUMBER, FREE STREAM, BIFURCATION(MATHEMATICS), DELTA WINGS, REYNOLDS NUMBER, PERIODIC VARIATIONS, STEADY FLOW, STAGNATION POINT, COUETTE FLOW, THREE DIMENSIONAL FLOW, AXISYMMETRIC FLOW, BURSTING STRENGTH.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE