Accession Number : ADP002265

Title :   Numerical Simulation of Vortex Breakdown by the Vortex-Filament Method,

Corporate Author : NATIONAL AERONUATICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER

Personal Author(s) : Nakamura,Y. ; Leonard,A. ; Spalart,P. R.

Report Date : JUL 1983

Pagination or Media Count : 13

Abstract : The vortex-filament method was applied to the simulation of vortex breakdown. The principal vortex region was represented by multiple filaments, and an axial velocity component was induced by a sprial winding of the filaments. First, an accuracy check was performed for a cylindrical swirling flow with simple analytical expressions for the axial and theta velocities. The result suggests that the flow field can be simulated to any accuracy by increasing the number of filaments. Second, an axisymmetric-type vortex breakdown was simulated, with experimental data serving as upstream conditions. The calculated axial-and theta-velocity contours show the breakdown of the vortex, including a rapid change in th vortex core, followed axially by a recovery zone and then a second breakdown. When three-dimensional initial data are used the second breakdown appears to be of the spiral type in correspondence with experimental observations. The present method can easily by used to simulate other types of vortex breakdown or other vortex flows with axial velocity. (Author)

Descriptors :   *Vortices, *Flow fields, Stability, Numerical methods and procedures, Accuracy, Equations of motion, Velocity, Downstream flow

Distribution Statement : APPROVED FOR PUBLIC RELEASE