```
GROUP 1. Run title and other preliminaries
TEXT(Jet Injection Into Polar Grid
TITLE
DISPLAY
The following five examples use a polar grid.  The GREX3
sequence in subroutine GXPOLR is used to set the inflow boundary
conditions by resolving the inflow velocity along the radial and
tangential directions, and fixing the U1 and V1 values at the
boundary cells to these resolutes.
ENDDIS
REAL(PI,VIN);PI=3.14159

GROUP 3. X-direction grid specification
CARTES=F;GRDPWR(X,18,PI,1.1)

GROUP 4. Y-direction grid specification
GRDPWR(Y,10,1.0,-1.7)

GROUP 7. Variables stored, solved & named
SOLVE(P1,U1,V1)

GROUP 9. Properties of the medium (or media)
ENUL=1.E-4;ENUT=0.0

GROUP 13. Boundary conditions and special sources
**Constant pressure boundary over periphery of domain
PATCH(PINF,NORTH,1,NX,NY,NY,1,1,1,1)
COVAL(PINF,P1,1.0E+06,0.0)
COVAL(PINF,U1,ONLYMS,0.0);COVAL(PINF,V1,ONLYMS,0.0)
**The PATCH names UPOL & VPOL are recognized by GREX3 as
ones which call for the activation of the sequence which
fixes the near-boundary velocities according to angular
location. Jet enters at  IX=1,IY=NY...
PATCH(UPOL,CELL,1,1,NY,NY,1,1,1,1)
COVAL(UPOL,U1,FIXVAL,SETSPEED)
**Set V1 at SOUTH face of boundary cell
PATCH(VPOL,CELL,1,1,NY-1,NY-1,1,1,1,1)
COVAL(VPOL,V1,FIXVAL,SETSPEED)

GROUP 15. Termination of sweeps
LSWEEP=50

GROUP 16. Termination of iterations
LITER(P1)=15;ENDIT(P1)=1.E-6

GROUP 17. Under-relaxation devices
RELAX(U1,FALSDT,10.);RELAX(V1,FALSDT,10.)

GROUP 19. Special calls from EARTH to GROUND
**Set inlet velocity: negative sign signifies velocity in -Y
direction at IX=1. The speed of the flow is set in POLRA
which is used in subroutine GXPOLR called in GREX3.
POLRA=-1.0

GROUP 22. Spot-value print-out
NPLT=2;IXMON=3;IYMON=3

GROUP 23. Field print-out and plot control
NXPRIN=NX/5;NYPRIN=NY/5
PATCH(MAP,CONTUR,1,NX,1,NY,1,1,1,1);PLOT(MAP,P1,1.0,10.0)
PLOT(MAP,U1,1.0,10.0);PLOT(MAP,V1,1.0,10.0)
```