Assessment of the nearly implicit solution scheme of RELAP5/MOD2: Numerical viscosity and suppression of oscillations

Conference · Fri Jan 01 04:00:00 EST 1988 · Transactions of the American Nuclear Society; (USA)

OSTI ID:5655770

Analytis, G Th

The nearly implicit hydrodynamic solution scheme of RELAP5/MOD2, which allows the code to run at time steps higher (for transients, 5 times) than the Courant limit was partly assessed with a low flooding rate reflooding experiment in the Neptune test facility. It is shown that for a large user-specified maximum time step, instabilities start appearing, which persist even after adding numerical viscosity terms (as is done in the semi-implicit scheme). Finally, it is shown that by linearization of the phasic velocity-dependent interfacial shear term, the instabilities are suppressed even if the (code-inherent) maximum time-step limit is increased to 10 times the Courant limit.

• OSTI ID: 5655770
• Report Number(s): CONF-881011--
• Conference Information: Journal Name: Transactions of the American Nuclear Society; (USA) Journal Volume: 57
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
220100* -- Nuclear Reactor Technology-- Theory & Calculation
42 ENGINEERING
420400 -- Engineering-- Heat Transfer & Fluid Flow
ACCIDENTS
COMPUTER CODES
FLUID MECHANICS
HYDRODYNAMICS
KINETICS
LOSS OF COOLANT
MECHANICS
R CODES
REACTOR ACCIDENTS
REACTOR KINETICS
SHEAR
STABILITY
TEST FACILITIES
TIME DEPENDENCE
TRANSIENTS