**RSICC CODE PACKAGE PSR-409**

**1. NAME AND TITLE**

KFIX: Code System to Calculate Transient 2-Dimensional 2-Fluid Flow Dynamics.

**2. CONTRIBUTORS**

Los Alamos National Laboratory, Los Alamos, New Mexico through Energy Science and Technology Software Center, Oak Ridge, Tennessee.

**3. CODING LANGUAGE AND COMPUTER**

FORTRAN IV; CDC 7600 (P00409C760000).

**4. NATURE OF PROBLEM SOLVED**

The transient dynamics of two-dimensional, two-phase flow with interfacial exchange are calculated at all flow speeds. Each phase is described in terms of its own density, velocity, and temperature. Separate sets of field equations govern the gas and liquid phase dynamics. The six field equations for the two phases couple through mass, momentum, and energy exchange.

**5. METHOD OF SOLUTION**

The equations are solved using an Eulerian finite difference technique that implicity couples the rates of phase transitions, momentum, and energy exchange to determination of the pressure, density, and velocity fields. The implicit solution is accomplished iteratively using a point relaxation technique without linearizing the equations, thus eliminating the need for numerous derivative terms. Solutions can be obtained in one and two space dimensions in plane geometry and in cylindrical geometry with axial symmetry and zero azimuthal velocity. Solutions in spherical geometry can also be obtained in one space dimension. The geometric region of interest is divided into many finite-sized, space-fixed zones called cells which form the computing mesh. In plane geometry the cells are rectangular cylinders, in cylindrical geometry they are toroids with rectangular cross section, and in spherical geometry they are spherical shells.

**6. RESTRICTIONS OR LIMITATIONS**

None noted.

**7. TYPICAL RUNNING TIME**

The sample problem took less than 14 CPU seconds to compile and less than 62 CPU seconds to calculate all variables for 140 time cycles on a CDC CYBER 170/875.

**8. COMPUTER HARDWARE REQUIREMENTS**

The sample problem, excluding plotting routines, required 55,000 (octal) words of memory on a CDC CYBER 170/875.

**9. COMPUTER SOFTWARE REQUIREMENTS**

KFIX was developed under SCOPE (CDC7600); NOS 2.4 (CDC CYBER170). A Fortran IV compiler is required.

**10. REFERENCES**

W. C. Rivard, M. D. Torrey, "K-FIX: A Computer Program for Transient, Two-Dimensional, Two-Fluid Flow," LA-NUREG-6623 (April 1977).

W. C. Rivard, M. D. Torrey, "PERM: Corrections to the K-FIX Code," LA-NUREG-6623, Suppl. (March 1978).

J. R. Travis, W. C. Rivard, "PRESBC: Pressure Boundary Conditions for the K-FIX Code," NUREG/CR-1536, LA-NUREG-6623, Suppl. III (July 1980).

L. Eyberger, "K-FIX, NESC No. 727.7600B," NESC Note 88-81 (June 30, 1988).

"Fortran Functions and System Subroutines in K-FIX" (May 1977).

**11. CONTENTS OF CODE PACKAGE**

Included in the package are the referenced documents, abstract and a DOS self-extracting file on one diskette which includes the source files, control info, and sample problems. No executables are included with the package.

**12. DATE OF ABSTRACT**

July 1999.

** KEYWORDS:** FLUID DYNAMICS; HEAT TRANSFER