GROUP 1. Run title TEXT(Shallow Sample Cup In Crosswind TITLE DISPLAY A simulation is made of the flow in and around a shallow open-topped hollow cylinder with a crosswind blowing across its top, normal to the cylinder axis. The height of the cup to its radius is 0.4 . This geometry is a design considered for a sampling cup used for measuring atmospheric precipitation. Cylindrical polar coordinates are used in 3 dimensions. The polar axis points vertically upwards from the ground surface, and the vertical extent of the domain extends well beyond the top of the sampling cup. The radial extent of the domain extends beyond the rim of the cup. The subroutine GXPOLR called from GREX3 is used to set boundary conditions at the cylindrical outer surface of the domain of integration, where a uniform stream of air is present. This is done in GXPOLR by resolving the inflow velocity along the radial and tangential directions of the grid, and fixing the U1 and V1 values at the boundary cells to these resolutes. ENDDIS REAL(PI,DY,AA);PI=3.14159 INTEGER(XFLOW1,XFLOW2,JJ1);XFLOW1=6;XFLOW2=15 GROUP 3. X-direction grid specification ** The domain is extended over 360 degrees in this example. CARTES=F;XCYCLE=T;GRDPWR(X,20,2.0*PI,1.0) GROUP 4. Y-direction grid specification YVLAST=0.1;NY=21 **Inside the cup 10 radial layers of cells are used, and beyond the rim of the cup 11 radial layers of cells are used. A geometric-progression grid spacing distribution is employed both sides of the cup wall to ensure adequate resolution of the flow at the exterior- and interior-side of the cup wall. YFRAC(10)=1.0;DY=.03;AA=1.2 DO JJ=9,1,-1 + JJ1=JJ+1 + YFRAC(JJ)=YFRAC(JJ1)-DY;DY=DY*AA ENDDO DY=.03;AA=1.4 DO JJ=11,19 + JJ1=JJ-1;YFRAC(JJ)=YFRAC(JJ1)+DY;DY=DY*AA ENDDO YFRAC(20)=3.5;YFRAC(21)=4.0 GROUP 5. Z-direction grid specification GRDPWR(Z,9,0.12,1.) GROUP 7. Variables stored, solved & named SOLVE(P1,U1,V1,W1);SOLUTN( P1,Y,Y,Y,N,N,N ) GROUP 9. Properties of the medium (or media) RHO1=1.205;ENUL=1.8E-5/RHO1;ENUT=ENUL*10. GROUP 11. Initialization of variable or porosity fields **The wall of the cup is represented by setting zero porosities at the cylindrical surface IY=10 . The minus signs preceding the number 10 flag the activation of wall friction at the inner and outer surface of the cup wall. CONPOR(0.0,NORTH,1,NX,-10,-10,1,NZ/3) GROUP 13. Boundary conditions and special sources ** The inlet region extends from pi/2 to 3pi/2. The wind- speed at the cylindrical inlet surface is set in POLRA which is resolved in subroutine GXPLOR into the tangential and radial directions. POLRA=4.0 PATCH(UPOL,CELL,XFLOW1-1,XFLOW2,NY,NY,1,NZ,1,1) COVAL(UPOL,U1,FIXVAL,GRND1) PATCH(VPOL,CELL,XFLOW1,XFLOW2,NY-1,NY-1,1,NZ,1,1) COVAL(VPOL,V1,FIXVAL,GRND1) ** The pressure is fixed to zero around the entire outer boundary of the domain... PATCH(PINF,CELL,1,NX,NY,NY,1,NZ,1,1) COVAL(PINF,P1,1.0E6,0.0 ) GROUP 15. Termination of sweeps LSWEEP=100;selref=t;resfac=0.1 GROUP 16. Termination of iterations LITER(P1) = 12;LITER(U1)=1;LITER(V1)=1 GROUP 17. Under-relaxation devices RELAX(U1,FALSDT,0.003);RELAX(V1,FALSDT,0.003) RELAX(W1,FALSDT,0.003) GROUP 21. Print-out of variables GROUP 22. Spot-value print-out IXMON=2;IYMON=12;IZMON=4 GROUP 23. Field print-out and plot control NPLT=2;NXPRIN=NX/5;NYPRIN=NY/5 PATCH(MAP,CONTUR,1,NX,1,NY,3,3,1,1) PLOT(MAP,P1,1.0,10.0);PLOT(MAP,U1,1.0,10.0) PLOT(MAP,V1,1.0,10.0);PLOT(MAP,W1,1.0,10.0)