Analysis of one-dimensional algorithms to use with operator splitting in programs for computing wave propagation. [Improvements to THREEDY code]

Technical Report · Sat Feb 01 04:00:00 EST 1975

OSTI ID:7209491

Hicks, D L; Lauson, H S; Madsen, M M

The analysis of the techniques of wavefitting, movable meshes, controlled entropy production, and an implicit-optional-explicit conservative discrete scheme indicates that these methods can be used to improve the THREEDY wavecode. THREEDY employs operator splitting. Operator splitting decomposes the three-dimensional operator into three one-dimensional operators, and thus simplifies the code. Wavefitting improves the accuracy around wavefronts. A movable mesh alleviates the severe distortion suffered in material coordinates on certain problems. The implicit-optional-explicit scheme is used to avoid the CFL (Courant, Friedrichs, and Lewy) constraint when it is overly restrictive. The explicit option is employed to save time by not iterating to the implicit solution when the CFL restriction happens to be satisfied by the growth restriction timestep. The growth restriction timestep prevents volumes and energies from changing too rapidly and/or going negative. Controlled entropy production avoids the extremes of severe oscillations associated with too little entropy production and excessive smearing with too much entropy increase.

• Research Organization: Sandia Labs., Albuquerque, N.Mex. (USA)
• DOE Contract Number: EY-76-C-04-0789
• OSTI ID: 7209491
• Report Number(s): SAND-74-0189
• Country of Publication: United States
• Language: English

Related Subjects

640410 -- Fluid Physics-- General Fluid Dynamics
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
99 GENERAL AND MISCELLANEOUS
990200* -- Mathematics & Computers
ALGORITHMS
COMPUTER CALCULATIONS
COMPUTER CODES
FLUID MECHANICS
HYDRODYNAMICS
MATHEMATICAL LOGIC
MATHEMATICAL OPERATORS
MECHANICS
ONE-DIMENSIONAL CALCULATIONS
SHOCK WAVES
T CODES
WAVE PROPAGATION