Accession Number : ADA302821

Title :   Influence of Geometric Approximations on Computational Results in Complex Tunnel Configurations.

Descriptive Note : Final rept.,

Corporate Author : S-CUBED ALBUQUERQUE NM

Personal Author(s) : Ekler, Robert G. ; Kennedy, Lynn W. ; Needham, Charles E.

PDF Url : ADA302821

Report Date : SEP 1995

Pagination or Media Count : 57

Abstract : This report describes a series of calculations undertaken to compare the effects of geometric approximations/simplifications commonly made when setting up hydrodynamic code simulations of blast and flow in tunnel systems. The approximations are made to save computer resources by running the calculation in two, rather than three, dimensions. A two-dimensional calculation requires less computational time by a factor of one to two orders of magnitude. It also requires less memory to run and less storage space for the computational output. In addition, setup and analysis times are reduced. The questions to be answered by this set of calculations, which included two different two-dimensional representations as well as a three-dimensional representation, are whether the approximations provide results that are sufficiently dose to those provided by calculating in three dimensions, and if so, which two-dimensional approximation is the best. The three calculational representations are set up in the coordinate systems available in SHARC (S-Cubed Hydrodynamic Advanced Research Code), a state-of-the-art, second- order-accurate, multi-material Eulerian hydrocode. These include a two-dimensional cylindrical system, a two-dimensional Cartesian (rectangular) system, and a three-dimensional Cartesian system. Each representation includes an explosive in a detonation chamber, an input tunnel, an expansion chamber, and an output tunnel connecting to the exterior. For each chamber, cross-sectional areas and chamber volumes are the same in each configuration. Yield of the explosive source must also be conserved among the different representations. How this was accomplished is explained in detail in the next section; however, the two-dimensional representations are not unique, and some alternatives are discussed in Section 6.

Descriptors :   *TUNNELS, *GEOMETRY, *HYDRODYNAMIC CONFIGURATIONS, INPUT, OUTPUT, SIMULATION, SOURCES, VOLUME, COMPUTATIONS, COMPUTERS, TWO DIMENSIONAL, EXPLOSIVES, TIME, CODING, CYLINDRICAL BODIES, APPROXIMATION(MATHEMATICS), COORDINATES, CROSS SECTIONS, HYDRODYNAMIC CODES, RESOURCES, EXPANSION, SPACE(ROOM), STORAGE, BLAST, CHAMBERS, DETONATIONS.

Subject Categories : Fluid Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE