NESC0802 SCHAFF

1. NAME OR DESIGNATION OF PROGRAM:  SCHAFF

3. DESCRIPTION OF PROBLEM OR FUNCTION

The     SCHAFF      (Slightly
Compressible  Heat  and  Fluid Flow)  program  was  developed  for
numerical modeling of liquid  geothermal systems involving natural
convection and hot  spring discharge.  For  one-, two-,  or three-
dimensional porous media, the single-phase fluid and heat transfer
equations  are solved  interlaced  in  time, using  an  integrated
finite difference  method.  The mathematical model  describing the
physical  behavior of  hot-water  geothermal  systems is  used  to
analyze natural or cellular convection  in permeable layers heated
from below.

4. METHOD OF SOLUTION

The  model  consists  of  a  set  of  coupled
partial  differential equations  for  heat  and mass  transfer  in
porous media  and an equation of  state relating fluid  density to
temperature.   Simultaneous  solution  of   the  flow  and  energy
equations is  accomplished by interlacing  the solutions  in time,
first assuming temperatures  and fluid densities constant  over an
interval  and  solving   for  new  fluid  pressure   and  velocity
distributions,   then  using   the  new   pressure  and   velocity
distributions  to  compute  new   temperature  and  fluid  density
distributions and so  on.  These equations are  solved numerically
using  an   integrated  finite  difference  method   which  treats
arbitrary nodal  configurations in  up to  three dimensions.   The
concepts  of fluid  and thermal  time constants  as indicators  of
nodal response times and numerical stability limits is an inherent
part of the numerical scheme.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The equations used
do  not include  source  terms.  With  a mass  source,  such as  a
recharge or discharge  well, the flow field  would not necessarily
equilibrate within each thermal cycle.

6. TYPICAL RUNNING TIME

SCHAFF requires approximately 30 seconds CP
time to complete the sample problem on a CDC7600.

7. UNUSUAL FEATURES OF THE PROGRAM:

8. RELATED AND AUXILIARY PROGRAMS:

10. REFERENCES

- M.L. Sorey:
  Numerical Modeling of Liquid Geothermal Systems
  Ph.D. Thesis, University of California, Berkeley, California
  (1975).

- M.J. Lippmann:
  Preparation of Input Data for Program SCHAFF (preliminary notes)
  Lawrence Berkeley Laboratory (May 1976)

11. MACHINE REQUIREMENTS

The  program  requires  approximately  110K
words of central memory for  execution.  Standard system input and
print and  punch output  units are required  along with  units for
temporary storage of two tape or disk files.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED:  SCOPE 2.1.

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS

     A
dummy HOUR  subroutine has been supplied  by NESC as  a substitute
for the LBL system routine of  that name which returns the current
wall-clock time  in A10 format.  The  user will have to  supply an
alternative routine applicable in the local environment.

15. NAME AND ESTABLISHMENT OF AUTHORS

                 M. L. Sorey and M. J. Lippmann*
                 Lawrence Berkeley Laboratory
                 Berkeley, California  94720
* Contact

File name	File description	Records
SCHAFF	SOURCE (F4,EBCDIC)	682
SCHAFF	S. P. INPUT DATA	1068
SCHAFF	S. P. OUTPUT	5811
SCHAFF	INFORMATIONS	5