# BFC for Dam break problem

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 January 18, 2001, 16:22 BFC for Dam break problem #1 Mehdi BEN ELHADJ Guest   Posts: n/a Sponsored Links Consider a horizontal and frictionless channel, which is 1000 m in lenght. A dam site is located at 500 m. The initial upstream-water depth is 10 m, and the vertical dimension of gaz layer is 3m. At time t=0, the dam is broken instantaneously. I use a space steps of 5 m (200 cells ) in horizontal direction ; 0,5 m (20 cells in upstream-water) in vertical direction and 3 cells in gaz layer in vertical direction. A time step is (20/100) s. I work with a (2-D) model and using implicit scheme for time and hybrid scheme for convection terms. I use SEM method (Scalar Equation Method) in PHOENICS code. So, If I simulate this case with a fixe cartesian mesh in BFC and with in BFC, I don't find the same results. **With BFC** TALK=T;RUN( 1, 1);VDU=x11-term GROUP 1. Run title and other preliminaries TEXT(Dam break : SEM) INTEGER(NY1,NY2,NZ1,NZ2) NX=1;NY1=100;NY2=100;NZ1=20;NZ2=3 NY=NY1+NY2 NZ=NZ1+NZ2 REAL(L1,L2,L3) L1=500.0 L2=500.0 L3=L2+L1 GROUP 2. Transience; time-step specification STEADY=F; LSTEP=100 ;TLAST=20 GRDPWR(T,LSTEP,TLAST,1.0) GROUP 3. X-direction grid specification NREGX=1 IREGX=1;GRDPWR(X,NX,1,1.0); GROUP 4. Y-direction grid specification NREGY=2 IREGY=1;GRDPWR(Y,NY1,L1,1.0); IREGY=2;GRDPWR(Y,NY2,L2,1.0); GROUP 5. Z-direction grid specification NREGZ=2; IREGZ=1;GRDPWR(Z,NZ1,10,1.0); IREGZ=2;GRDPWR(Z,NZ2,3,1.0); GROUP 6. Body-fitted coordinates or grid distortion BFC=T;SETBFC=T;MOVBFC=T GROUP 7. Variables stored, solved & named STORE(VOLU,CONI,CONJ,CONK) STORE(DEN1,PRPS); SOLVE(VFOL,SURN) SOLUTN(P1,Y,Y,Y,N,N,N) SOLUTN(V1,Y,Y,N,N,N,N) SOLUTN(W1,Y,Y,N,N,N,N) GROUP 8. Terms (in differential equations) & devices ** activate the "gas-and-liquid algorithm", ie volumetric continuity equation, and allow convection fluxes to be modified in GROUND GALA=T; TERMS(VFOL,N,N,N,N,P,P) TERMS(SURN,N,N,N,N,P,P) DIFCUT=0.0 UCONV=T GROUP 9. Properties of the medium (or media) ** signal that density is to be computed by the HOL method and set the densities of the liquid and gas respectively RHO1=GRND10 ENUL=GRND10 GROUP 11. Initialization of variable or porosity fields FIINIT(CONI)=0.0;FIINIT(CONJ)=0.0;FIINIT(CONK)=0.0 FIINIT(P1)=0.0;FIINIT(V1)=0.0;FIINIT(W1)=0.0; FIINIT(SURN)=0.0; FIINIT(PRPS)=0. FIINIT(DEN1)=1.189; INIADD=F PATCH(LIQUID,INIVAL,1,NX,1,NY1,1,NZ1,1,1) init(LIQUID,SURN,ZERO,1) init(LIQUID,VFOL,ZERO,1) init(LIQUID,PRPS,ZERO,67) init(LIQUID,DEN1,ZERO,1000.5) GROUP 13. Boundary conditions and special sources ** the pressure is held to zero along the open top boundary PATCH(REFP,CELL,1,NX,1,NY,NZ,NZ,1,LSTEP) COVAL(REFP,P1,FIXVAL,ZERO) ** provide for the gravity-force source of w1 PATCH(GRAV,PHASEM,1,NX,1,NY,1,NZ,1,LSTEP) COVAL(GRAV,W1,FIXFLU,-9.81) GROUP 15. Termination of sweeps LSWEEP=50; LITER(SURN)=1 GROUP 16. Termination of iterations SELREF=T;RESFAC=0.01 GROUP 17. Under-relaxation devices RELAX(P1,LINRLX,0.7) RELAX(V1,FALSDT,0.1) RELAX(W1,FALSDT,0.1) GROUP 19. Data communicated by satellite to GROUND ** provide for the dumping of field data at each time step, for us by PHOTON USEGRX=T;USEGRD=F;LSG60=T IDISPA=1;IDISPB=1;IDISPC=LSTEP;CSG1=W CSG2=XYZ IPRPSA=67;IPRPSB=0; SURF=T; RLOLIM=0.4;RUPLIM=0.6 VARMIN(SURN)=0.0; VARMAX(SURN)=1.0 ISG1=1 RSG1=0.0;RSG2=1.0 RSG3=0.0;RSG4=L3 RSG5=0.0;RSG6=13 RSG7=1.0;RSG8=1.0; RSG9=1.0;RSG10=1.0; RSG11=1.0;RSG12=1.0 RSG13=0.0;RSG14=0.0;RSG15=0.0 GROUP 22. Spot-value print-out TSTSWP=-1 ECHO=T IYMON=2*NY/3;IZMON=NZ/2 GROUP 23. Field print-out and plot control OUTPUT(P1,N,N,N,N,Y,Y);OUTPUT(V1,N,Y,N,Y,Y,Y) OUTPUT(W1,N,N,N,N,Y,Y);OUTPUT(SURN,N,N,N,N,N,N) OUTPUT(DEN1,N,N,N,N,N,N) OUTPUT(VFOL,Y,N,N,N,Y,Y); OUTPUT(IMB1,N,Y,N,Y,Y,Y); OUTPUT(ENUL,N,N,N,N,Y,Y);OUTPUT(RHO1,N,N,N,N,N,N) OUTPUT(PRPS,N,N,N,N,N,N) NTPRIN=100 NYPRIN=1 NZPRIN=1 IPROF=2 XZPR=T STOP **With out BFC** TALK=T;RUN( 1, 1);VDU=X11-TERM GROUP 1. Run title and other preliminaries TEXT(Dam break: SEM) INTEGER(NY1,NY2,NZ1,NZ2) NY1=100;NY2=100;NZ1=20;NZ2=3 NY=NY1+NY2 NZ=NZ1+NZ2 GROUP 2. Transience; time-step specification STEADY=F; LSTEP=100 ;TLAST=20 GRDPWR(T,LSTEP,TLAST,1.0) GROUP 4. Y-direction grid specification NREGY=2 IREGY=1;GRDPWR(Y,NY1,500,1.0); IREGY=2;GRDPWR(Y,NY2,500,1.0); GROUP 5. Z-direction grid specification NREGZ=2; IREGZ=1;GRDPWR(Z,NZ1,10,1.0); IREGZ=2;GRDPWR(Z,NZ2,3,1.0); GROUP 7. Variables stored, solved & named STORE(DEN1,PRPS); SOLVE(VFOL,SURN) SOLUTN(P1,Y,Y,Y,N,N,N) SOLUTN(V1,Y,Y,N,N,N,N) SOLUTN(W1,Y,Y,N,N,N,N) GROUP 8. Terms (in differential equations) & devices ** activate the "gas-and-liquid algorithm", ie volumetric continuity equation, and allow convection fluxes to be modified in GROUND GALA=T; TERMS(VFOL,N,N,N,N,P,P) TERMS(SURN,N,N,N,N,P,P) GROUP 9. Properties of the medium (or media) ** signal that density is to be computed by the HOL method and set the densities of the liquid and gas respectively RHO1=GRND10 ENUL=GRND10 GROUP 11. Initialization of variable or porosity fields FIINIT(P1)=0.0;FIINIT(V1)=0.0;FIINIT(W1)=0.0; FIINIT(SURN)=0.0; FIINIT(PRPS)=0. FIINIT(DEN1)=1.189; INIADD=F PATCH(LIQUID,INIVAL,1,NX,1,NY1,1,NZ1,1,1) init(LIQUID,SURN,ZERO,1) init(LIQUID,VFOL,ZERO,1) init(LIQUID,PRPS,ZERO,67) init(LIQUID,DEN1,ZERO,1000.5) GROUP 13. Boundary conditions and special sources ** the pressure is held to zero along the open top boundary PATCH(REFP,CELL,1,NX,1,NY,NZ,NZ,1,LSTEP) COVAL(REFP,P1,FIXVAL,ZERO) ** provide for the gravity-force source of w1 PATCH(GRAV,PHASEM,1,NX,1,NY,1,NZ,1,LSTEP) COVAL(GRAV,W1,FIXFLU,-9.81) GROUP 15. Termination of sweeps LSWEEP=50; LITER(SURN)=1 GROUP 16. Termination of iterations SELREF=T;RESFAC=0.01 GROUP 17. Under-relaxation devices RELAX(P1 ,LINRLX,0.7) RELAX(V1,FALSDT,1) RELAX(W1,FALSDT,1) GROUP 19. Data communicated by satellite to GROUND ** provide for the dumping of field data at each time step, for us by PHOTON IDISPA=LSTEP;IDISPB=1;IDISPC=LSTEP;CSG1=W IPRPSA=67;IPRPSB=0; SURF=T; RLOLIM=0.4;RUPLIM=0.6 VARMIN(SURN)=0.0; VARMAX(SURN)=1.0 GROUP 22. Spot-value print-out TSTSWP=-1 ECHO=T IYMON=2*NY/3;IZMON=NZ/2 GROUP 23. Field print-out and plot control OUTPUT(P1,N,N,N,N,Y,Y);OUTPUT(V1,N,Y,N,Y,Y,Y) OUTPUT(W1,N,N,N,N,Y,Y);OUTPUT(SURN,N,N,N,N,N,N) OUTPUT(DEN1,N,N,N,N,N,N) OUTPUT(VFOL,Y,N,N,N,Y,Y); OUTPUT(IMB1,N,Y,N,Y,Y,Y) OUTPUT(ENUL,N,N,N,N,Y,Y);OUTPUT(RHO1,N,N,N,N,N,N) OUTPUT(PRPS,N,N,N,N,N,N) NTPRIN=100 NYPRIN=1 NZPRIN=1 IPROF=2 XZPR=T STOP

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