```

PHOTON USE
p

gr out z 1
gr out z 1 x 1 4 y 1 8
text
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Five isothermal particles are introduced in
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text
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the domain. Two of the particles start
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their journey in the recirculation region.
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All the particles are under the combined
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effect of drag and inertia.
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upause 1
GEOMETRY READ
T00001
upause 3
GEOMETRY READ
T00002
upause 3
GEOMETRY READ
T00003
upause 3
GEOMETRY READ
T00004
upause 3
GEOMETRY READ
T00005
upause 5
set vec ref
50
vec z 1
upause 2
text
3

Press  to end
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pause
enduse

TEXT(Backward-facing step  : G200
TITLE
DISPLAY
This simulation  concerns incompressible, turbulent flow
over a backward-facing step in a two-dimensional closed
channel. Particles are injected immediately after the
backward-facing step. The Stochastic Turbulence Model
is used to simulate particle dispersion due to turbulence.
wall
/////////////////////////////////////////////////////
-----------------------------------------------------
Pressure
Inlet  ------->                              --------->  fixed at
zero
/________________
| ////////////////|                                  Exit
|       wall     /| Recirculation
|                /|  <----                ----->
|                /|____________________________________
|                //////////////////////////////////////
|                                  wall
\
ENDDIS
INTEGER(NYS,NXS)
REAL(HEIGHT,WIDTH,CLEN,SLEN,REYNO,UIN,TKEIN,EPSIN,GENUT)
** Calculation of domain specifications
HEIGHT=0.0381;WIDTH=3.*HEIGHT;SLEN=4.*HEIGHT;CLEN=20.*HEIGHT
NXS=4;NYS=10;REYNO=4.5E4;UIN=13.
GROUP 1. Run title and other preliminaries
GROUP 2. Transience; time-step specification
GROUP 3. X-direction grid specification
NX=20;XULAST=1.0
** Full length of channel = 0.762
XFRAC(1)=-4.0;XFRAC(2)=3.81E-2;XFRAC(3)=16.0;XFRAC(4)=3.81E-2
GROUP 4. Y-direction grid specification
NY=15;YVLAST=1.0
** Full width of channel = 0.1143
YFRAC(1)=-10.0;YFRAC(2)=3.81E-3;YFRAC(3)=5.0;YFRAC(4)=1.524E-2
GROUP 7. Variables stored, solved & named
SOLVE(P1,U1,V1);SOLUTN(P1,Y,Y,Y,N,N,N);TURMOD(KEMODL);STORE(ENUT)
GROUP 8. Terms (in differential equations) & devices
DIFCUT=0.0
GROUP 9. Properties of the medium (or media)
RHO1=1.0;ENUL=UIN*HEIGHT/REYNO
GROUP 10. Inter-phase-transfer processes and properties
GROUP 11. Initialization of variable or porosity fields
** Calculation of KE (where fric=0.018)...
TKEIN=0.25*UIN*UIN*0.018
** Calculation of EP (where lmix=0.09 x h)...
EPSIN=TKEIN**1.5*0.1643/3.429E-3
** Initial values
FIINIT(U1)=UIN;FIINIT(P1)=1.3E-4;FIINIT(KE)=TKEIN;FIINIT(EP)=EPSIN
** Initialization of variables in blocked region
CONPOR(0.0,CELL,1,-NXS,1,-NYS,1,1)
GROUP 13. Boundary conditions and special sources
**  Inlet
INLET(GXINLET,WEST,1,1,NYS+1,NY,1,1,1,1)
VALUE(GXINLET,P1,UIN);VALUE(GXINLET,U1,UIN)
VALUE(GXINLET,KE,TKEIN);VALUE(GXINLET,EP,EPSIN)
**  Exit
PATCH(GXOUT,EAST,NX,NX,1,NY,1,1,1,1);COVAL(GXOUT,P1,1.0E5,0.0)
COVAL(GXOUT,U1,ONLYMS,0.0);COVAL(GXOUT,V1,ONLYMS,0.0)
COVAL(GXOUT,KE,ONLYMS,0.0);COVAL(GXOUT,EP,ONLYMS,0.0)
**    N-wall
WALL(WFUNNORT,NORTH,1,NX,NY,NY,1,1,1,1)
**    S2-wall
WALL(WFUNSOUT,SOUTH,NXS+1,NX,1,1,1,1,1,1)
GROUP 14. Downstream pressure for PARAB=.TRUE.
GROUP 15. Termination of sweeps
LSWEEP=170
GROUP 16. Termination of iterations
RESREF(U1)=1.E-6;RESREF(P1)=1.E-6;RESREF(V1)=1.E-6
RESREF(KE)=1.E-6;RESREF(EP)=1.E-6
GROUP 17. Under-relaxation devices
RELAX(U1,FALSDT,1.0E-2);RELAX(V1,FALSDT,1.0E-2)
RELAX(KE,FALSDT,1.0E-2);RELAX(EP,FALSDT,1.0E-2)
GROUP 22. Monitor print-out
IYMON=NYS-2;IXMON=NXS+2;NPRMON=100
GROUP 23. Field print-out and plot control
NPLT=1;IPLTL=LSWEEP;NXPRIN=2;NYPRIN=2; TSTSWP=-1
PATCH(MAP,CONTUR,1,NX,1,NY,1,1,1,1)
PLOT(MAP,P1,0.0,10.0);PLOT(MAP,U1,0.0,10.0)
PLOT(MAP,V1,0.0,10.0);PLOT(MAP,KE,0.0,10.0)
PLOT(MAP,EP,0.0,10.0)
#GENTRA
*-------------------------------------------------------
* GENTRA GROUP 1: Particle physics
*-------------------------------------------------------
* Particle type - PARTICLES_IN_ISOTHERMAL_FLOW
GPTYPE=30
* Gravity components /buoyancy
GGRAX=0;GGRAY=0;GGRAZ=0;GBUOYA=F
* Stochastic model of turbulence
GSTOCH=T
* Data for particles in isothermal flow
GDRAG=-10120
*-------------------------------------------------------
* GENTRA GROUP 2: Boundary conditions for particles
*-------------------------------------------------------
* Inlet data
--------------------------------------
* X      Y          U      V         DIA   RHO   MASSFLO
0.0E+00  9.0E-02   11.5 -8.45E-00  1.E-05  100.  5.08E-05
0.0E+00  7.0E-02   11.5 -8.45E-00  1.E-05  100.  5.08E-05
0.0E+00  5.0E-02   4.57 -3.79E-01  1.E-05  100.  1.36E-04
2.4E-01  0.1E-02   1.80 -5.57E-01  1.E-05  100.  1.99E-04
2.0E-01  1.0E-02   8.54 -3.07E-01  1.E-05  100.  1.14E-04
---------------------------------------
* Wall treatment, and rest coefficient if appropriate
GWALLC=3;GWREST=1.0
* Porosity threshold
GPOROS=0
*-------------------------------------------------------
* GENTRA GROUP 3: Numerical controls
*-------------------------------------------------------
* 1st GENTRA sweep; frequency of calls
GSWEP1=1;GSWEPF=20
* Maximum Lagrangian time-step
GDTMAX=1;GRTFRC=100000.
* Min # of t-steps per cell; max # of t-steps; timeout
GLAGTS=5;GSTEMX=1000;GTIMMX=3.0
*-------------------------------------------------------
* GENTRA GROUP 4: Output controls
*-------------------------------------------------------
* Trajectory-file identifier, history-file identifier
and frequency for output
GT1STC=T;GSWOUT=10;NGWSTR=1;NGWEND=20;NGWINT=1
*-------------------------------------------------------
* PIL provisions for the GENTRA-Earth run
*-------------------------------------------------------
* Storage for interphase sources of momentum
STORE(MOMX);STORE(MOMY)
* Storage for cell residence-time
STORE(REST)
* Interphase sources of heat and momentum
PATCH(GENPAT,CELL,1,NX,1,NY,1,NZ,1,LSTEP)
COVAL(GENPAT,3,FIXFLU,GRND);COVAL(GENPAT,5,FIXFLU,GRND)
* Relaxation of interphase sources
GLNRLX=1.0
RELAX(MOMX,LINRLX,GLNRLX);RELAX(MOMY,LINRLX,GLNRLX)
L(GENSET
* ----------------------------------------------------------
* GENTRA GROUP 7: GENTRA test
* ----------------------------------------------------------
* GENTRA auto test  RG(51)--RG(58) are reserved
RG(51)= 6.86E-01;RG(52)= 6.42E+02;RG(53)= 4.91E-03
RG(54)= 3.81E+00;RG(55)= 1.68E-01;RG(56)= 2.50E+00
RG(57)= 5.00E+16;RG(58)= 5.00E-02
```