AFDM: An Advanced Fluid-Dynamics Model

Technical Report · Sat Sep 01 00:00:00 EDT 1990

DOI:https://doi.org/10.2172/6664961· OSTI ID:6664961

Bohl, W R; Parker, F R ^[1]; Wilhelm, D ^[2]; Berthier, J ^[3]; Goutagny, L ^[4]; Ninokata,

---

1. Los Alamos National Lab., NM (USA)
2. Kernforschungszentrum Karlsruhe GmbH (Germany, F.R.). Inst. fuer Neutronenphysik und Reaktortechnik
3. CEA Centre d'Etudes Nucleaires de Grenoble, 38 (France)
4. CEA Centre d'Etudes Nucleaires de Cadarache, 13 - Saint-Paul-lez-Durance (France). Inst. de Protection et de Surete Nucleaire

AFDM, or the Advanced Fluid-Dynamics Model, is a computer code that investigates new approaches simulating the multiphase-flow fluid-dynamics aspects of severe accidents in fast reactors. The AFDM formalism starts with differential equations similar to those in the SIMMER-II code. These equations are modified to treat three velocity fields and supplemented with a variety of new models. The AFDM code has 12 topologies describing what material contacts are possible depending on the presence or absence of a given material in a computational cell, on the dominant liquid, and on the continuous phase. Single-phase, bubbly, churn-turbulent, cellular, and dispersed flow regimes are permitted for the pool situations modeled. Virtual mass terms are included for vapor in liquid-continuous flow. Interfacial areas between the continuous and discontinuous phases are convected to allow some tracking of phenomenological histories. Interfacial areas are also modified by models of nucleation, dynamic forces, turbulence, flashing, coalescence, and mass transfer. Heat transfer is generally treated using engineering correlations. Liquid-vapor phase transitions are handled with the nonequilibrium, heat-transfer-limited model, whereas melting and freezing processes are based on equilibrium considerations. Convection is treated using a fractional-step method of time integration, including a semi-implicit pressure iteration. A higher-order differencing option is provided to control numerical diffusion. The Los Alamos SESAME equation-of-state has been implemented using densities and temperatures as the independent variables. AFDM programming has vectorized all computational loops consistent with the objective of producing an exportable code. 24 refs., 4 figs.

• Research Organization: Los Alamos National Lab., NM (USA)
• Sponsoring Organization: USNRC
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 6664961
• Report Number(s): LA-11692-MS-Vol.1; ON: DE90016723; TRN: 90-029492
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE
LMFBR TYPE REACTORS
LOSS OF FLOW
MULTIPHASE FLOW
S CODES
COMPUTERIZED SIMULATION
CORIUM
EVAPORATION
HEAT TRANSFER
HYDRAULICS
PRESSURE DROP
PRESSURE EFFECTS
REACTOR SAFETY
SENSITIVITY
STABILITY
TEMPERATURE EFFECTS
TRANSIENTS
VAPORS
VELOCITY
ACCIDENTS
BREEDER REACTORS
COMPUTER CODES
ENERGY TRANSFER
EPITHERMAL REACTORS
FAST REACTORS
FBR TYPE REACTORS
FLUID FLOW
FLUID MECHANICS
FLUIDS
GASES
LIQUID METAL COOLED REACTORS
MECHANICS
PHASE TRANSFORMATIONS
REACTOR ACCIDENTS
REACTORS
SAFETY
SIMULATION
220900* - Nuclear Reactor Technology- Reactor Safety
210500 - Power Reactors
Breeding
990200 - Mathematics & Computers