TALK=T;RUN(1,1) 255
```
DISPLAY
An inviscid fluid flows steadily in a direction normal
to a flat plate. Since the potential-flow equation which
represents this situation is identical with that for flow
through a highly resistive medium obeying Darcy's law, it
is the latter problem which is solved, a device which is
effected by the command DARCY=T. This entails that the
pressure values computed correspond to 1.0E4 times the
velocity potential.
SELREF is set=f in order to prevent premature termination.

The geometry of the problem is as follows:

frictionless wall
-----------------------------------------------------
-------->
-------->
---->                   PLATE             ---->
|
^  ---->                     |               ---->
|                            |
y| ---------------------------|-------------------------
|                    frictionless wall
z--->
ENDDIS
PHOTON USE
p;;;;;;

con p1 x 1 fi;0.001
msg contours of potential
pause
con w1 x 1 fi;0.001
msg contours of axial velocity
pause
con off;red
vec x 1 sh
msg velocity vectors
ENDUSE

GROUP 1. Run title and other preliminaries
TEXT(Potential Flow over Perpendicular Plate
TITLE

GROUP 4 & 6
ny=20; yvlast=4.0; nz=40; zwlast=8.0
l(unigrid

GROUP 7. Variables stored, solved & named
SOLVE(P1,V1,W1); SOLUTN(P1,Y,Y,Y,N,N,N)

GROUP 8. Terms (in differential equations) & devices
TERMS(V1,Y,Y,N,P,P,P); TERMS(W1,Y,Y,N,P,P,P)

GROUP 11. Initialization of variable or porosity fields
FIINIT(P1)=0.0

GROUP 13. Boundary conditions and special sources
**Upstream boundary
PATCH(UPSTRM,LOW,1,1,1,NY,1,1,1,1)
COVAL(UPSTRM,P1,FIXVAL,4.0)
COVAL(UPSTRM,V1,ONLYMS,0.0); COVAL(UPSTRM,W1,ONLYMS,0.0)
**Downstream boundary
PATCH(DWNSTRM,HIGH,1,1,1,NY,NZ,NZ,1,1)
COVAL(DWNSTRM,P1,FIXVAL,-4.0)
COVAL(DWNSTRM,V1,ONLYMS,0.0); COVAL(DWNSTRM,W1,ONLYMS,0.0)
**Plate
PATCH(PLAT,HIGH,1,1,1,NY/2,NZ/2,NZ/2,1,1)
COVAL(PLAT,W1,FIXVAL,0.0)
**Distributed resistance
DARCY=T

GROUP 15. Termination of sweeps
LSWEEP=30

GROUP 16. Termination of iterations
LITER(P1)=-200

GROUP 21. Print-out of variables
OUTPUT(P1,Y,Y,Y,Y,N,N); OUTPUT(V1,Y,Y,Y,Y,N,N)
OUTPUT(W1,Y,Y,Y,Y,N,N)

GROUP 22. Spot-value print-out
IYMON=NY/2; IZMON=NZ/2; IPLTF=2
tstswp=-1
GROUP 23. Field print-out and plot control
NYPRIN=NY/10; IZPRF=16; IZPRL=25
PATCH(PROF,PROFIL,1,1,1,NY,NZ/2,NZ/2,1,1)
PLOT(PROF,W1,0.0,0.0)
PATCH(CONT,CONTUR,1,1,1,NY,1,NZ,1,1); PLOT(CONT,P1,0.0,20.0)
PLOT(CONT,W1,0.0,20.0); PLOT(CONT,V1,0.0,40.0)
SELREF=F
```