```

TEXT(Pot. Flow; Inclined Plate
TITLE
DISPLAY

A plate is held centrally in a square box through the wall of
which flows an inviscid fluid.

The velocity potential at the walls accords with the formula:

POT = aa * x   +   bb * y
where aa = -1 and bb = -1
(which can of course be changed by editing the Q1 file)

The task is to compute the flow field within the box.

In-Form is used in order to specify the boundary condition.

The plate is represented by setting area porosity to zero.

The Q1 uses SOURCE In-Form statement.

The Q1 contains PHOTON USE commands
ENDDIS
PHOTON USE
p
phi

msg         Potential flow past an inclined plate
msg
set ref vec 5
msg   Velocity vectors:
gr ou z 1;vec z 1 sh
msg
msg Press  to continue
pause
vec off;red
msg        west to east velocity contours:
con u1 z 1 fi;.01
msg
msg Press  to continue
pause
msg        south to north velocity contours:
con v1 z 1 fi;.01
msg
msg Press  to continue
pause
con off;red
msg        Streamlines and contours of velocity potential:
con pot z 1 sh; int 20
stre 2d z 1 sh; int 20
msg Press e to END
enduse
GROUP 1. Run title and other preliminaries
TEXT(Pot. Flow; Inclined Plate
TITLE
GROUPs 3, 4 and 5: grid specification
nx=40; ny=40; nz=1
xulast=1.0; yvlast=1.0; zwlast=1.0
#unigrid

GROUP 7. Variables stored, solved & named
STORE(POT,EPOR,U1,V1); SOLUTN(POT,Y,Y,Y,N,N,N)

GROUP 11. Initialization of variable or porosity fields
FIINIT(EPOR)=1.0
**Plate
PATCH(PLATE,INIVAL,NX/2,NX/2,NY/4+1,3*NY/4,1,1,1,1)
INIT(PLATE,EPOR,FIXVAL,0.0)

GROUP 13. Boundary conditions and special sources
PATCH(NORTH,NORTH,2, NX-1,NY,NY,1,1,1,1)
PATCH(SOUTH,SOUTH,2, NX-1,1 ,1 ,1,1,1,1)
PATCH(EAST ,EAST ,NX,NX,  1 ,NY,1,1,1,1)
PATCH(WEST ,WEST ,1 , 1,  1 ,NY,1,1,1,1)
INFORM13BEGIN
REAL(AA,BB)
AA=-1; BB=-1
(source of POT at north is aa*xg + bb*yg with fixval)
(source of POT at south is aa*xg + bb*yg with fixval)
(source of POT at east  is aa*xg + bb*yg with fixval)
(source of POT at west  is aa*xg + bb*yg with fixval)
INFORM13END

GROUP 15. Termination of sweeps
LSWEEP = 2
GROUP 16. Termination of iterations
LITER(POT)=-1000
GROUP 19. Data communicated by satellite to GROUND
POTVEL=T
GROUP 21. Print-out of variables
OUTPUT(EPOR,N,N,N,N,N,N)
GROUP 22. Spot-value print-out
UWATCH=T
GROUP 23. Field print-out and plot control
PATCH(CONT,CONTUR,1,NX,1,NY,1,1,1,1);PLOT(CONT,POT,0.0,20.0)
DISTIL=T
EX(U1)=8.072E-01; EX(V1)=1.005E+00; EX(POT)=1.000E+00
```