NESC0948 SOLA-VOF.

1. NAME OR DESIGNATION OF PROGRAM:  SOLA-VOF.

3. DESCRIPTION OF PROBLEM OR FUNCTION

SOLA-VOF is a program for the solution of two-dimensional transient fluid flow with free boundaries, based on the concept of a fractional volume of fluid (VOF). Its basic mode of operation is for single fluid calculations  having multiple free surfaces. However, SOLA-VOF can also be used for calculations involving two fluids separated by a sharp interface. In either case, the fluids may be treated as incompressible or as having limited compressibility. Surface tension forces with wall adhesion are permitted in both cases. Internal obstacles may be defined by blocking out any desired combination of  cells in the mesh, which is composed of rectangular cells of variable size.

4. METHOD OF SOLUTION

The basis of the SOLA-VOF method is the fractional volume of fluid scheme for tracking free boundaries. In this technique, a function F(x,y,t) is defined whose value is unity  at any point occupied by fluid and zero elsewhere. When averaged over the cells of a computational mesh, the average value of F in a  cell is equal to the fractional volume of the cell occupied by fluid. In particular, a unit value of F corresponds to a cell full of fluid, whereas a zero value indicates that the cell contains no fluid. Cells with F values between zero and one contain a free surface. SOLA-VOF uses an Eulerian mesh of rectangular cells having  variable sizes. The fluid equations solved are the finite difference approximations of the Navier-Stokes equations.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The setting of array dimensions is controlled through PARAMETER statements.

6. TYPICAL RUNNING TIME

The sample problem requires about 38 seconds  to compile and execute on a CDC CYBER175.
NEA-DB executed the test case on CDC 7600 in 13 CPU seconds.

7. UNUSUAL FEATURES OF THE PROGRAM

Several automatic features are included, such as a generator for variable meshes, an automatic time-step control, and routines to identify and label disjoint void  regions.

8. RELATED AND AUXILIARY PROGRAMS

SOLA is a simplified version of the basic SOLution Algorithm used in the Marker-And-Cell method, and SOLA-SURF is an extended version of SOLA that uses a surface height  function method to treat free surfaces (NESC Abstract 651). SOLA-VOF was developed from SOLA-VM, a variable mesh version of the SOLA code. PELE-IC (NESC Abstract 865) was developed from the basic semi-implicit solution algorithm of SOLA.

10. REFERENCES

- C.W. Hirt, B.D. Nichols, and N.C. Romero,
  SOLA-A Numerical Solution Algorithm for Transient Fluid Flow,
  LA-5852, April 1975.
- C.W. Hirt and B.D. Nichols,
  Volume of Fluid (VOF) Method for the Dynamics of Free Boundaries,  Journal of Computational Physics (to be published).
- C.W. Hirt and B.D. Nichols,
  Adding Limited Compressibility to Incompressible Hydrocodes,
  Journal of Computational Physics, Vol. 34, pp. 390-400, 1980.

- B.D. Nichols, C.W. Hirt and R.S. Hotchkiss:
  SOLA-VOF: A Solution Algorithm for Transient Fluid Flow with
  Multiple Free Boundaries. LA-8355 UC-32 and UC-34 (August 1980)
  and Errata no. 1 (November 8, 1980)

11. MACHINE REQUIREMENTS

72,000 (octal) words of memory.
Main storage requirements on CDC 7600 are 41,000 octal words.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  SCOPE (CDC7600),  NOS (CDC CYBER175).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

SOLA-VOF calls Los Alamos system-dependent graphics routines written for the SC-4020 film recorder which are not included in the package. Dummy routines were supplied by NESC. These LANL routines are described in the reference report and must be replaced with suitable alternatives for the local computer environment if plotting is desired.

15. NAME AND ESTABLISHMENT OF AUTHOR

             B.D. Nichols*, C.W. Hirt and R.S. Hotchkiss
             Los Alamos National Laboratory
             P.O. Box 1663
             Los Alamos, new Mexico 87545
* Contact

File name	File description	Records
NESC0948_03.001	Information file	32
NESC0948_03.002	SOLA-VOF source program (FORTRAN)	2738
NESC0948_03.003	SOLA-VOF test case input data	9
NESC0948_03.004	SOLA-VOF test case printed output	1243