1. NAME AND TITLE

COMMIX-1C: 3-D Single-Phase Thermal Hydraulics.
 

2. CONTRIBUTORS

Argonne National Laboratory, Argonne, Illinois and US DOE Pittsburgh Energy Technology Center, Pittsburgh, Pennsylvania through the Energy Science and Technology Software Center, Oak Ridge, Tennessee.
 

3. CODING LANGUAGE AND COMPUTER

FORTRAN 77; Cray, RS/6000, Sun (P00393MNYCP00) (1996 release).

Previous versions available: COMMIX-1B for Vax and IBM Mainframes.

(P00393DVX1100 and P00393I303300) (1991 release).
 

4. NATURE OF PROBLEM SOLVED

COMMIX-1C is designed to perform steady-state or transient, single-phase, three-dimensional analysis of fluid flow with heat transfer in a single-component or multicomponent system. The program was developed for the analysis of heat transfer and fluid flow processes in a nuclear reactor system; however, it can easily be applied to non-nuclear systems requiring heat transfer and/or fluid flow analysis. COMMIX-1C solves the conservation equations of mass, momentum, and energy, and transport equations of turbulence parameters and provides detailed local velocity, temperature, and pressure fields for the problem under consideration. It is capable of solving thermal-hydraulic problems involving either a single component, such as a rod bundle, reactor plenum, piping system, heat exchanger, etc., or a multicomponent system that is a combination of these components.
 

5. METHOD OF SOLUTION

COMMIX-1C uses the finite-difference approach to solve the conservation equations of mass, momentum, and energy and transport equations of turbulence parameters. These equations are solved as a boundary-value problem in space and an initial-value problem in time. The solution of the equations is achieved by the successive over relaxation procedure. The staggered grid system is used, which considers the field variables as located at the center of a cell and flow variables as located at the surface of a cell. In COMMIX-1C, the finite-difference discretization equations are formulated by integrating the conservation equations over a control volume. There are two alternative formulation schemes in COMMIX-1C. One is semi-implicit and is a modification of the ICE technique. It is ideally suited for analyzing fast transients. The other, a fully implicit scheme called SIMPLEST-ANL, is a modification of the numerical procedure known as SIMPLER. It is particularly suitable for the analysis of slow and normal transients.
 

6. RESTRICTIONS OR LIMITATIONS

Maxima of 99 calculational cells in each of the x, y, and z directions, 99 surfaces, 50 user-defined rebalancing regions, 20 correlation types available for force structures, 10 heat transfer correlations, and 10 materials.
 

7. TYPICAL RUNNING TIME

Running time is dependent on the size and complexity of the problem being simulated and can vary from a few seconds to several hours of CPU time.
 

8. COMPUTER HARDWARE REQUIREMENTS

COMMIX-1C runs on Cray, IBM RS/6000 and Sun computers. Problem size determines the memory requirements, which range from 550K to several megabytes.

COMMIX-1B ran on DEC Vax 11 under VMS 5.2 or on IBM 3033 under VM/CMS.
 

9. COMPUTER SOFTWARE REQUIREMENTS

Version 1C runs on Unix-based operating systems and requires Fortran 77 and C compilers. Version 1B requires a Fortran 77 compiler and an assembler for the IBM version.
 

10. REFERENCES

a) Included in documentation:

H. M. Domanus, Y. S. Cha, T. H. Chien, R. C. Schmitt, W. T. Sha, "COMMIX-1C: A Three-Dimensional Transient Single-Phase Computer Program for Thermal-Hydraulic Analysis of Single-Component and Multicomponent Engineering Systems, Equations and Numbers," NUREG/CR-5649, ANL-90/33, Vol. 1 (November 1990).

H. M. Domanus, Y. S. Cha, T. H. Chien, R. C. Schmitt, W. T. Sha, "COMMIX-1C: A Three-Dimensional Transient Single-Phase Computer Program for Thermal-Hydraulic Analysis of Single-Component and Multicomponent Engineering Systems, User's Guide and Manual," NUREG/CR-5649, ANL-90/33, Vol. 2 (November 1990).
 

b) Background information:

"COMMIX-1B: A Three-Dimensional Transient Single-Phase Computer Program for Thermal Hydraulic Analysis of Single and Multicomponent Systems Volume I: Equations and Numerics," NUREG/CR-4348, ANL-85-42 Vol. I (September 1985) and Erratum (January 31, 1986).

"COMMIX-1B: A Three-Dimensional Transient Single-Phase Computer Program for Thermal Hydraulic Analysis of Single and Multicomponent Systems Volume II: User's Manual," NUREG/CR-4348, ANL-85-42, Vol., II (September 1985).

"COMIX-1B, NESC No. R1066.VAX, COMMIX-1B DEC VAX Version tape Description and Implementation Information, NESC Note 91-98 (September 6, 1991).

"COMMIX-1B, NESC No. R1066.3033C, COMMIX-1B Edition C Tape Description and Implementation Information," NESC Note 91-97 (September 6, 1991).
 

11. CONTENTS OF CODE PACKAGE

Included are the referenced documents in (10.a) and one diskette which include the source code, makefiles, and input/output files written in a self-extracting compressed DOS file. No executables are provided with the package.
 

12. DATE OF ABSTRACT

April 1999.
 

KEYWORDS: HEAT TRANSFER; THERMAL HYDRAULICS