PHOTON USE p phi 5 1 msg grid gr z 1 msg Pressto continue pause cl msg 1st-phase velocity vectors at t=5s set vec ref;2 set vec comp au1 cv1 - vec z 1 sh gr ou z 1 msg Press to continue pause cl msg 2nd-phase velocity vectors at t=5s set vec ref;0.25 set vec comp bu2 dv2 - vec z 1 sh gr ou z 1 msg Press to continue pause cl msg contour of pressure at t=5s con p1 z 1 fi;0.002 gr ou z 1 msg Press to continue pause cl msg contour of 1st-phase volume fraction at t=5s con r1 z 1 fi;0.002 gr ou z 1 msg Press to continue pause cl msg contour of 1st-phase volume fraction at t=5s con r2 z 1 fi;0.002 gr ou z 1 msg Press e to END enduse GROUP 1. Run title and other preliminaries TEXT(TRANSIENT 2PH FLOW WITH MOVING WALL:W441 TITLE DISPLAY A light fluid lies above a heavy one in a box of which the lid is suddenly set in motion. A vortex begins to form in the upper fluid, and a second one,rotating in the opposite direction, in the lower one. This is a transient problem, much easier to conceive than to solve. A point to watch for is:does the sharp discontinuity of the volume fraction, characterising the interface, remain intact? It should be observed that a number of special devices have been activated in order to promote convergence, for example EQDVDP (which causes the velocities of the two fluids to be adjusted by equal amounts at the correction stage) and ISWR1=5 (which allows 5 sweeps of velocity adjustment, at each time step, before the volume fractions are solved for). The choices and settings of these convergence-promoting parameters may not be the best, so the search for better ones could prove instructive. ENDDIS GROUP 2. Transience; time-step specification STEADY=F;GRDPWR(T,5,5.0,1.0) GROUP 3. X-direction grid specification GRDPWR(X,5,1.0,1.0) GROUP 4. Y-direction grid specification GRDPWR(Y,5,1.0,1.0) GROUP 7. Variables stored, solved & named ONEPHS=F;SOLVE(P1,U1,V1,U2,V2,R1,R2) SOLUTN(P1,P,P,P,P,P,N) SOLUTN(U1,P,P,P,P,P,N);SOLUTN(U2,P,P,P,P,P,N) SOLUTN(V1,P,P,P,P,P,N);SOLUTN(V2,P,P,P,P,P,N) SOLUTN(R1,P,P,P,P,P,N);SOLUTN(R2,P,P,P,P,P,N) NAME(U1)=AU1;NAME(U2)=BU2;NAME(V1)=CV1;NAME(V2)=DV2 GROUP 8. Terms (in differential equations) & devices ** Make the velocity-pressure sensitivity coefficients (i.e. the d(vel)/dp's ) for both phases equal to the weighted average (by volume fraction) of the ones for each phase. EQDVDP=T;RHO2=1.E3 GROUP 9. Properties of the medium (or media) ENUL=1.E-3 GROUP 10. Inter-phase-transfer processes and properties ** Set a constant inter-phase friction coefficient. CFIPS=1.E5 GROUP 11. Initialization of variable or porosity fields FIINIT(R1)=1.0;FIINIT(R2)=0.0;FIINIT(P1)=0.0 FIINIT(AU1)=0.;FIINIT(CV1)=0.;FIINIT(BU2)=0.;FIINIT(DV2)=0. INIADD=T PATCH(INIT,INIVAL,1,NX,1,2,1,1,1,1) INIT(INIT,R1,0.0,-1.0);INIT(INIT,R2,0.0,1.0) INIT(INIT,P1,0.0,1.0E3) GROUP 13. Boundary conditions and special sources ** Pressure relief PATCH(REFP,CELL,1,NX,NY,NY,1,1,1,LSTEP);COVAL(REFP,P1,1.E-5,0.0) ** Moving wall WALL (MOVWALL,NORTH,1,NX,NY,NY,1,1,2,LSTEP) COVAL(MOVWALL,AU1,1.0,1.0) ** West wall WALL (WFUNWEST,WEST,1,1,1,NY,1,1,1,LSTEP) COVAL(WFUNWEST,CV1,1.0,0.0);COVAL(WFUNWEST,DV2,1.0,0.0) ** East wall WALL (WFUNEAST,EAST,NX,NX,1,NY,1,1,1,LSTEP) COVAL(WFUNEAST,CV1,1.0,0.0);COVAL(WFUNEAST,DV2,1.0,0.0) ** South wall WALL (WFUNSOUT,SOUTH,1,NX,1,1,1,1,1,LSTEP) COVAL(WFUNSOUT,BU2,1.0,0.0) ** Gravity PATCH(GRAVITY,PHASEM,1,NX,1,NY,1,1,1,LSTEP) COVAL(GRAVITY,CV1,FIXFLU,-10.0);COVAL(GRAVITY,DV2,FIXFLU,-10.0) GROUP 15. Termination of sweeps ISWR1=5 LSWEEP=20;RESREF(P1)=1.E-5;RESREF(R1)=1.E-5;RESREF(R2)=1.E-5 GROUP 17. Under-relaxation devices RELAX(R1,LINRLX,0.1);RELAX(R2,LINRLX,0.1) RELAX(AU1,FALSDT,0.01);RELAX(CV1,FALSDT,0.001) RELAX(BU2,FALSDT,0.01);RELAX(DV2,FALSDT,0.01) SPEDAT(SET,GXMONI,TRANSIENT,L,F) GROUP 22. Spot-value print-out IXMON=4;IYMON=4 GROUP 23. Field print-out and plot control NTPRIN=10;ITABL=1;IPLTL=100;TSTSWP=-1 PATCH(CONT,CONTUR,1,NX,1,NY,1,1,1,LSTEP) PLOT(CONT,R2,0.0,10);PLOT(CONT,BU2,0.0,10) PLOT(CONT,AU1,0.0,10) PATCH(IXEQ2,PROFIL,2,2,1,NY,1,1,1,LSTEP) PLOT(IXEQ2,AU1,-0.05,0.05);PLOT(IXEQ2,P1,0.0,4.E3)