NESC0737 DIFFUSER

1. NAME OR DESIGNATION OF PROGRAM:  DIFFUSER

3. DESCRIPTION OF PROBLEM OR FUNCTION

The DIFFUSER  program uses  a
turbulent-flow model  to   calculate  the   performance  of   two-
dimensional subsonic diffusers and  of three-dimensional diffusers
under the  assumption of similarity of  the top, bottom,  and side
wall boundary layers.

4. METHOD OF SOLUTION

The analytical model used is the Patankar and
Spalding two-dimensional boundary layer  computer code modified to
handle internal  channel flows.  The numerical  algorithm employed
is a variable grid implicit finite difference scheme used to solve
the von  Mises form  of the  conservation of  momentum and  energy
equations  for  turbulent  flow.   At  each  integration  step  an
iteration procedure is performed to  predict the pressure gradient
such that the mass flow is conserved.

5. RESTRICTIONS ON THE COMPLEXITY OF THE PROBLEM

The  code   cannot
handle properly 1)  the modeling of the  turbulent Reynolds stress
in an  adverse pressure  gradient with  large boundary  layers, 2)
interaction  corner effects  of the  boundary layers  on the  four
walls  of the  channel, 3)  transitionary stall  and 4)  separated
flow.

6. TYPICAL RUNNING TIME

Running time is dependent on the number of grid points and maximum step sizes as well as the geometry input specified. With 77 grid points across the diffuser the execution time is about 7.5 seconds for every 100 integration steps (2 meters for a 2 cm step size). The sample problem executed in 21 CPU seconds on an IBM370/195.

NEA-DB executed the test case included in this package  on an IBM 3084 computer in 6 seconds of CPU time.

7. UNUSUAL FEATURES OF THE PROGRAM

The code calculates the solution
of  the  conservation equations  from  wall  to wall  rather  than
separating core  flow from boundary  layer flow;  thereby yielding
better results on the calculated pressure fields.

8. RELATED AND AUXILIARY PROGRAMS:  The code  as presented  is  self-
contained.

10. REFERENCES

- S.V. Patankar and D.B. Spalding:
  Heat and  Mass Transfer in Boundary Layers
  Margon-Grampian, London  (1967)

- E. Doss and H. Geyer:
  Two-Dimensional Subsonic DIFFUSER Code
  ANL/MHD-77-1 (July 1977)
- ACC Note 78-13 (January 4, 1978)

11. MACHINE REQUIREMENTS:  125K bytes of memory

The test case was executed on IBM 3084 in 256K bytes of main storage.

13. OPERATING SYSTEM UNDER WHICH PROGRAM IS EXECUTED

OS/370 MVT/ASP system with ANL-AMD function library, SYS1.FORTLIB2.

MVS-SP (IBM 3084).

14. OTHER PROGRAMMING OR OPERATING INFORMATION OR RESTRICTIONS:

15. NAME AND ESTABLISHMENT OF AUTHORS

                 E. Doss and H. Geyer
                 Engineering Division
                 Argonne National Laboratory
                 9700 South Cass Avenue
                 Argonne, Illinois  60539

File name	File description	Records
NESC0737_01.001	Information file	49
NESC0737_01.002	DIFFUSER source program (fortran IV)	1330
NESC0737_01.003	DIFFUSER Test case input data	10
NESC0737_01.004	DIFFUSER Test case printed output	637