GROUP 1. Run title and other preliminaries
TEXT(Backward-Facing Step;2-Fluid Model: 976
TITLE

DISPLAY
This is an example of the application of the
two-fluid model of turbulence to non-reacting,
turbulent flow over a backward-facing step, as
illustrated:

////////////////////////////////////////////////
Inlet                                       Exit
-------->
W2                                   ---------->
////////////
/  Recirculation
/ <----                    ------->
/////////////////////////////////////

The geometry considered has a expansion ratio of 1.5
and an exit width of 3h, where h is the step height.
The calculations are started at x=-4h and terminated
at x=16h. The flow is incompressible.

In the present calculations, the fluid 1 is defined as
that which moves away from the stepped wall and fluid 2
as that moves towards it respectively.
ENDDIS
It is postulated that only fluid 2 enters the duct at the inlet,
and that it is converted into fluid 1 there by entrainment.
The boundary condition employed here is an extreme one to
emphasise the role of inter-fluid transport of mass and
momentum.
The same flow situation is described in input library
case(290),in which the standard form of the k-e model
is employed. Users may compare the results between the
two and vary the model constants and boundary conditions
to explore their effects on the solutions.
INTEGER(NYS,NZS)
REAL(WIN,HIGHT,WIDTH,Cf,Cm,Cvw,Ct)
WIN=18.2;HIGHT=0.0381;WIDTH=HIGHT*3.0;NYS=15;NZS=6
**** Model constants ****
Cf=0.05;Cm=10.0;Cvw=1.0;Ct=1.0
GROUP 4. Y-direction grid specification
*** The width of duct is 0.1143
NREGY=2;IREGY=1;GRDPWR(Y,15,HIGHT,1.0)
IREGY=2;GRDPWR(Y,15,WIDTH-HIGHT,1.0)
GROUP 5. Z-direction grid specification
*** The length of duct is 0.762
GRDPWR(Z,30,HIGHT*20,1.0)
GROUP 7. Variables stored, solved & named
ONEPHS=F
SOLVE(P1,V1,V2,W1,W2,R1,R2);SOLUTN(P1,Y,Y,Y,N,N,N)
NAME(W1)=SW1;NAME(W2)=FW2;NAME(R1)=AR1;NAME(R2)=BR2
NAME(V1)=CV1;NAME(V2)=DV2
INTMDT=22;NAME(INTMDT)=MDOT;LEN1=23;NAME(LEN1)=LEN
VIST=24;NAME(VIST)=VIS
SOLUTN(MDOT,Y,N,N,N,N,N);SOLUTN(LEN,Y,N,N,N,N,N)
SOLUTN(VIS,Y,N,N,N,N,N)
GROUP 9. Properties of the medium (or media)
*** Length scale
EL1=NIKURCH
*** Densities
RHO1=1.0;RHO2=1.0
*** Laminar-viscosity
ENUL=1.E-6
*** Turbulent-viscosity
ENUT=2FLUID;ENUTA=Ct
GROUP 10. Inter-phase-transfer processes and properties
*** Ierter-fluid friction
CFIPS=GRND4;CFIPA=0.0;CFIPB=1.0;CFIPC=Cf;CFIPD=-1.0
*** Inter-fluid mass transfer
CMDOT=GRND1;CMDTA=Cm;CMDTB=0.5;CMDTC=0.0
GROUP 11. Initialization of variable or porosity fields
FIINIT(SW1)=WIN;FIINIT(FW2)=WIN;FIINIT(AR1)=0.5;FIINIT(BR2)=0.5
*** To block the step
CONPOR(0.0,CELL,1,1,1,-NYS,1,-NZS)
GROUP 13. Boundary conditions and special sources
*** Inlet
INLET(INLET,LOW,1,1,NYS+1,NY,1,1,1,1)
VALUE(INLET,P2,WIN*0.5);VALUE(INLET,FW2,WIN)
VALUE(INLET,P1,WIN*0.5);VALUE(INLET,SW1,WIN)
*** Exit
PATCH(OUTLET,HIGH,1,1,1,NY,NZ,NZ,1,1)
COVAL(OUTLET,P1,1.E5,0.0);COVAL(OUTLET,P2,1.E5,0.0)
COVAL(OUTLET,CV1,ONLYMS,0.0);COVAL(OUTLET,DV2,ONLYMS,0.0)
COVAL(OUTLET,SW1,ONLYMS,0.0);COVAL(OUTLET,FW2,ONLYMS,0.0)
*** North-wall
WALL (NORTHWAL,NORTH,1,1,NY,NY,1,NZ,1,1)
COVAL(NORTHWAL,SW1,1.0,0.0);COVAL(NORTHWAL,FW2,1.0,0.0)
*** South-wall
WALL (SOUTHWAL,SOUTH,1,1,1,1,NZS+1,NZ,1,1)
COVAL(SOUTHWAL,SW1,1.0,0.0);COVAL(SOUTHWAL,FW2,1.0,0.0)
*** Momentum source in the normal-to-wall-velocity equations
PATCH(SHSO,CELL,1,1,1,NY,1,NZ,1,1)
COVAL(SHSO,CV1,FIXFLU,GRND5);COVAL(SHSO,DV2,FIXFLU,GRND5)
SHSOA=Cvw
GROUP 15. Termination of sweeps
LSWEEP=100
GROUP 17. Under-relaxation devices
RELAX(P1,LINRLX,1.0);RELAX(AR1,LINRLX,0.25)
RELAX(BR2,LINRLX,0.25);RELAX(CV1,FALSDT,0.0001)
RELAX(DV2,FALSDT,0.0001);RELAX(SW1,FALSDT,0.001)
RELAX(FW2,FALSDT,0.001);RELAX(MDOT,LINRLX,0.5)
GROUP 21. Print-out of variables
OUTPUT(AR1,N,N,N,N,N,N);OUTPUT(MDOT,Y,Y,Y,Y,Y,Y)
PATCH(LPRO1,PROFIL,1,1,1,1,NZS,NZ,1,1)
COVAL(LPRO1,P1,0.0,0.0)
PATCH(LPRO2,PROFIL,1,1,NY,NY,NZS,NZ,1,1)
COVAL(LPRO2,P1,0.0,0.0)
PATCH(WPRO,PROFIL,1,1,1,NY,8,8,1,1)
COVAL(WPRO,SW1,1.0,1.0);COVAL(WPRO,FW2,1.0,1.0)
COVAL(WPRO,CV1,0.1,0.1);COVAL(WPRO,DV2,0.1,0.1)
GROUP 22. Spot-value print-out
IYMON=NYS-2;IZMON=NZS+2;IPLTL=1000
NPLT=2;NYPRIN=2
GROUP 24. Dumps for restarts