Two-Fluid Modeling of Oil-Water Flow Bottom Water
Draw-Off Concept
Y. H. Zurigat
B. A. Jubran
L. Khezzar
S. Alfar
Sultan Qaboos University, Department of Mechanical and Industrial Engineering,
Muscat, Sultanate of Oman
Abstract:
In this study the problem of Bottom Water Draw-Off (BWDO) in stratified oilwater flow in pipelines is investigated using the Inter-Phase-Slip Algorithm embedded in
the Phoenics software. This problem is frequently encountered in oil production pipelines
with relatively high water cut. The conditions simulated are those obtained from field
tests for a 68-cm I.D. pipeline. The flow conditions in this pipe result in stratified flow of
relatively oil-free water at the bottom and oil-in-water dispersion at the top. The BWDO
from two consecutive 90o draw-off branches 5-meter apart was simulated using a twofluid model. Using the model the draw-off water quality was calculated for different
draw-off flow rates.
INTRODUCTION
Oil production in many parts of the world is characterized by high water cut. This may
be attributed to the production practice or the nature of reservoir formation. Excessively
high production rates often result in formation water intrusions that ultimately produced
with the oil. Also, water produced in the process is frequently re-injected into reservoirs
to maintain enough pressure for production enhancement. Thus, more water is produced
and the water cut may reach high values ranging between 80-95%. This places an
overwhelming economic burden on oil-water separation facilities to cope with the
increased oil production and the associated large water production.
1
In oil production pipelines with high water cut the concept of Bottom Water Draw Off
(BWDO) (see Fig. 1) is an effective tool in cutting down the cost of separating the oil and
water fluids. With the increased production the BWDO could obviate the need for new
FWKO tank. Also, the required pumping power and pipeline size are reduced resulting in
handling the increased production with the existing pipeline system.
Oil in Water
Emulsion
Interface
Bottom-Water
Draw-off pipe
Figure 1 Schematics of bottom water draw-off system (Khezzar and Zurigat, 2000)
Numerical modeling of BWDO concept relies on the type of flow pattern existing
under the flow conditions encountered. Oil-water flow patterns have been investigated by
several researchers (Russell et al., 1959; Charles et al., 1961; Oglesby, 1979; Brauner and
Maron, 1989; Theron and Unwin, 1996; Bessette and Jepson, 1997; Shi et al., 2001).
From the published experimental work, six flow patterns of oil/water flows in pipes have
been identified. In the water dominated flows, when the oil superficial velocity is fixed
( Vos  0.8 m / s ) and the water superficial velocity is increased gradually, the oil
entrainment in the water phase increases and the following flow patterns are reached
sequentially: stratified flow, stratified flow with mixing at the interface, dispersion of oil
in water and water layer and finally oil in water dispersion as shown in Fig. 2. On the
other hand, when oil is the dominant phase ( Vos  0.8 m / s ), the water entrainment is
enhanced. Initially, water is fully dispersed in the oil. Then, increasing the water
superficial velocity induces the coalescence of the water drops, leading finally to the oil
becoming fully dispersed in the water.
2
Stratified Flow
Stratified Flow with Mixing at the interface
Dispersion of oil in water and water layer
Oil in water Emulsion
Figure 2 Horizontal (water dominated) oil-water flow pattern sketches (Trallero et
al., 1997)
The BWDO concept relies heavily on the occurrence of stratified flow wherein the oil
and water liquids are segregated with little mixing at the interface. Khezzar and Zurigat,
(2000) have conducted numerical experiments to shed light on the design aspects of
BWDO concept using single-phase flow modeling coupled with particle tracking
technique. Simulations were conducted to establish BWDO system design and operating
conditions for a single and two consecutive draw-off pipes. For a single draw-off pipe,
the variation of draw-off water quality with draw-off flow rate for three possible
locations of dispersion-water interface of 25, 28 and 30 cm was obtained and the
threshold flow rate beyond which the water quality starts to deteriorate was established.
Comprehensive results on these simulations have appeared in Zurigat and Khezzar
(2002).
Under certain flow and fluid conditions (low flow rates) stratified liquid-liquid flow in
pipelines appears naturally in several engineering applications such as oil and process
industries. In this connection several modeling studies on this topic have appeared in the
3
open literature. For horizontal pipes notable works include those of Russell et al. (1959),
Charles et al. (1961), Brauner and Maron (1989) and (1992), Arirachakaran et al. (1989).
Two-fluid models employing full Navier-Stokes equations were developed by Hall and
Hewitt (1993), and Kurban (1997). Theron and Unwin (1996) developed stratified
(liquid-liquid) flow model for interpreting production logging data for horizontal wells in
order to assist in measuring the oil and water flow rates. Based on their model the slip
velocity can be evaluated using only holdup and total flow rate measurements. The slip
velocity in turn is used to determine the flow rates of individual phases.
This paper reports an extension to the earlier CFD work of BWDO system
(Khezzar and Zurigat, 2000; Zurigat and Khezzar, 2002) using a two-fluid model which
is more realistic than the single-fluid model in simulating the BWDO concept. Moreover,
the paper reports preliminary CFD results on the effects of drawing different flow rates
of water from the first and the second draw-off pipes, on the quality of the drawn water
as well as the height of oil-water interface. The effects of using various turbulence
models to simulate BWDO are also investigated.
MATHEMATICAL MODEL
The model makes use of the Inter-Phase-Slip Algorithm (IPSA) which solves the
full averaged Navier-Stokes equations for each phase. The IPSA has been used in
PHOENICS since 1981 to predict thermal and hydrodynamic characteristics of
multiphase flows. Calculations were performed on the basis of two-fluid model. The full
Reynolds equations of motion for turbulent flow are written for each phase. For steady
incompressible flow these equations are:
div U i   0
(1)
div U iU j   ij    gradP
(2)

where U i is the mean velocity vector, P the mean pressure and ij the usual stress tensor
given by :
4
 Ui
 ij    
 x j

U j 2 Ui 

 ij    ui' u'j
xi 3 x j 
(3)
The Reynolds stress tensor is modeled with the aid of a turbulent eddy viscosity. Thus:
u i' u 'j 
t

  U i U j


 x
x i
j

 2
  k ij
 3

(4)
where k and  t are the turbulent kinetic energy and the turbulent viscosity, respectively.
The turbulent viscosity is expressed differently depending on the turbulence model used.
For example, in the k-e model it is given by :
 t  C
k2

(5)
and  is the kinetic energy isotropic rate of dissipation.
To obtain the turbulence kinetic energy and its dissipation rate various turbulence
models have been used in this work with the ISPA namely; the standard k-  , Chen-Kim
k-  , k-  and LEVL models. Moreover, the two phases are considered to have the same
pressure but the IPSA is capable of allowing the presence of a contact pressure between
the two phases when the volume fraction is close to one. The IPSA is capable of solving
up to three velocity components and one volume fraction for each phase. This is done by
using the Eulerian-Eulerian technique with a fixed grid and employing the concept of
'interpenetrating continua' to solve a complete set of equations for each phase.
In this simulation oil/water flow is treated as a stratified one with the aim of
investigating the effect of the rate of bottom water draw-off on the interface height in the
main pipe and the quality of drawn-off water. A horizontal pipe of a length of 9 m and
0.68 m in diameter with two bottom water draw-off pipes is used as shown in Fig. 1. The
diameter of the draw-off pipe branch is 0.24 m with a length of 0.5m. The distance
5
between the draw-off pipes is taken to be 5m. A uniform grid mesh was used (Fig.3) and
a grid dependency test runs were done to explore the grid dependency and the number of
iterations of the converged solution. The runs indicated that a 250x25x50 cells provide a
acceptable solution. Oil and water are taken at stratified inlet conditions with an initial
interface height corresponding to 85% water cut. The inlet boundary conditions were
fixed for both phases in terms of equal velocity corresponding to total flow rate of 56160
m3/day and equal concentrations of 100% for each phase. The inlet turbulence intensity
is assumed to be 5%. The bottom water draw-off volumetric flow rates from pipe
branches were varied to investigate their effects on the interface heights and water
quality.
Figure 3: The grid used in the x-z plane
RESULTS AND DISCUSSION
The computational results were carried out using a Pentium 3 PC with 1.2 GHz
speed. A converged solution was obtained after 1500 iterations and a CPU time of about
12 hours. Figures 4 and 5 show the velocity vector and counter plots of the flow at the
center plane of both draw-off pipes for flow rates of 3000 m3 / day and 5000 m3 / day
from the first and second pipes, respectively. Figure 6 shows the velocity profile across
the pipe upstream of the first draw-off pipe predicted by different turbulence models. It
can be seen from these figures that the flow at the vicinity and in the draw-off pipe is
6
characterized by re-circulation which causes blockage of flow and reduces effective area
for draw-off. Moreover, due to draw-off higher velocity is observed in the bottom part of
the pipe and, by continuity (please define V1 and h), a corresponding decrease at the top
(see Figs. 5 and 6). That is, the velocity profile is asymmetric as expected. Figure 7
shows the oil concentration contours, R 2 in the system. It can be seen that the
stratification
Pipe 2
Pipe 1
Figure 4: Velocity vector plots in the vicinity of bottom water draw off pipes at draw-off
flow rates of 3000 and 5000 m3 / day from the first and second pipes, respectively.
7
Pipe 1
Pipe 2
Figure 5: Velocity contour plots in the vicinity of bottom water draw off pipes for the
conditions of Fig. 4.
characteristic of the flow is evident upstream and above the first draw-off pipe. The oilwater interface is quite clear and the mixing region on both sides of the interface is
relatively thin compared with that in the second draw-off pipe region where the pure oil
layer seen in pipe 1 region has disappeared downstream in pipe-2 region. Clearly, more
mixing has been introduced as a result of draw-off. The maximum oil concentration in
outflow from the first draw-off pipe ( R 2 ) is 87 ppm and increases to 1194 ppm in the
second pipe.
8
1.85
1.8
1.75
V1 (m/s)
1.7
1.65
x=1.9, KEP
1.6
x=1.9, Level Model
1.55
x=1.9, KECHEN
1.5
1.45
1.4
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
h/D
Figure 6: Phase 1 (water) velocity distribution across the main pipe (h measured from
the bottom of the pipe)at a fixed axial location of 1.9m from the entrance to
the main pipe for different turbulence models.
9
Pipe 1
Pipe 2
Figure 7: Oil concentration contour plots in the vicinity of bottom water draw-off pipes
at equal draw-off flow rates of 3000 m3 / day .
Increasing the bottom water draw off from 5000 m3 / day in the second pipe to
10,000 m3 / day while maintaining the same draw off rate of 3000 m3 / day in the first
pipe resulted in lower interface and high mixing and circulation in the second pipe and
deterioration of the water quality, Figure 8.
10
Pipe1
Pipe2
Figure 8: Oil concentration contour plots in the vicinity of bottom water
draw-off pipes at high draw-off rate from the second pipe.
100.00%
90.00%
x=0
80.00%
x=1.9
R2
70.00%
x=4.5
60.00%
x=6.9
50.00%
x=9
40.00%
30.00%
15% Oil
20.00%
10.00%
0.00%
0
0.2
0.4
0.6
0.8
1
h/ D
Figure 9: Oil concentration profiles (R2) across the main pipe for different axial
locations using standard k-  model at flow rate of 3000 m3/day from both
draw-off pipes.
11
Figure 9 shows the oil distributions R 2 at different axial locations along the main pipe at
equal draw-off flow rate of 3000 m 3 / day . The evolution of the oil-water interface
height along the pipe is determined based on 85% water cut criterion (or 15% oil in water
concentration). That is, the interface height is taken as the height from the bottom of the
main pipe where R 2 is 15%. It can be clearly seen that as the distance is increased along
the pipe in the x-direction, the interface height is reduced. At 10 cm upstream of the first
pipe the height/diameter ratio h/D is 0.72 (0.49 m from the bottom of the pipe) and
decreases to 0.64 (0.44m) at 10 cm upstream of the second pipe.
The effect of turbulence models on the distribution of R 2 at 10 cm upstream of the first
draw-off pipe is shown in Fig. 10 for equal draw-off flow rate of 3000 m 3 / day . The
figure indicates that both the standard k-  , and Chen-Kim k-  gave exactly the same
distribution while the k-  and Level model produced different concentration profiles.
Clearly, the latter two models are more dissipative than the first two. Also, the Level
model produces the highest degree of mixing across the pipe. This is evident from the
slope of the curve and the extent of the mixed region predicted by the model. The effect
of turbulence models on the velocity distribution as shown in Fig. 6 is slightly less
compared with that on concentration distributions.
1.00E+00
9.00E-01
x=1.9, KEP
8.00E-01
x=1.9, Level Model
7.00E-01
x=1.9, Model KL
R2
6.00E-01
x=1.9, KECHEN
5.00E-01
4.00E-01
3.00E-01
2.00E-01
1.00E-01
0.00E+00
0
0.2
0.4
0.6
0.8
1
h/D
Figure 10: Oil concentration distribution across the main pipe at different axial locations
using different turbulence models.
12
The effect of varying the draw-off flow rate from the first and second pipes on drawnoff water quality and the oil/water interface was investigated. Figure 11 shows the effect
of varying the flow rate from the first draw-off pipe while maintaining a constant flow
rate of 3000 m3 / day from the second pipe. As the flow rate is increased the oil
concentration R 2 increases. The increase, however, is insignificant, i.e., from 20 to 170
ppm at 4000 and 10,000 m3 / day , respectively. The 170 ppm is considered much lower
than the allowable limit of 1200 to 2000 ppm employed by the field engineers. Figure 12
shows the effect of varying the flow rate in the first draw-off pipe on the drawn-off water
quality from the second draw-off pipe. As the draw-off is increased in the first pipe the
quality of the drawn-off water from the second pipe (Q2) is decreased, i.e., R 2 is
increased. This is due to the decrease in oil-water interface height downstream of the first
draw-off pipe as a result of draw-off from the first pipe. Also, the draw-off from the first
pipe introduces interface disturbances and more mixing and widening of the mixed flow
region, hence the high oil concentration in the second pipe.
1.800E-04
1.600E-04
1.400E-04
R2
1.200E-04
1.000E-04
Q1
8.000E-05
6.000E-05
4.000E-05
2.000E-05
0.000E+00
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
Flow Rate From The First Draw-off pipe (m^3/day)
Figure 11: Maximum value of oil concentration in the first draw-off pipe at a constant
flow rate of 3000 m3/day in the second draw-off pipe.
13
9.00E-03
8.00E-03
7.00E-03
R2
6.00E-03
5.00E-03
Q2
4.00E-03
3.00E-03
2.00E-03
1.00E-03
0.00E+00
0
2000
4000
6000
8000
10000
12000
Flow Rate From The First Draw-off pipe (m^3/day)
Figure 12: Maximum value of oil concentration in the second draw-off pipe as a function
of flow rate from the first draw-off pipe at a fixed flow rate of 3000m3/day
from the second pipe
Table 1 shows the effect of water withdrawal on the oil/water interface just 10 cm
upstream of both pipes based on the 15% oil concentration criterion. Increasing the drawoff from the first pipe from 3000 to 10,000 m3/day results in a decrease in the interface
level by 20%. The first column in Table 1 indicates that the draw-off flow rate does not
affect the interface level ahead of the draw-off point. Figure 13 shows the effect of drawoff from the second draw-off pipe on the interface downstream of that pipe for two
different water cut values. It is seen that the water cut significantly affects the allowable
draw-off rate as the interface level significantly decreases as the water cut decreases.
More results will be obtained on the variation of interface level and draw-off system
performance.
14
0.35
0.3
0.25
h/D
0.2
0.15
h/D at 1200ppm for 95% water cut
h/D at 1200ppm for 85% water cut
0.1
0.05
0
2000
3000
4000
5000
6000
7000
8000
9000
10000
11000
Draw-off Flow Rate, m^3/day
Figure 13. Variation of interface position after the second draw-off point for a 1200 ppm
cut-off oil concentration for different draw-off flow rates and two different
water cut values.
Table 1: Oil/water interface heights at different bottom water draw-off rates
BD1
BD2
(m 3 / day)
(m 3 / day)
h/D at x=1.9 m
h/D at x=6.9 m
3000
3000
0.724
0.64
4000
3000
0.72
0.63
5000
3000
0.72
0.62
7000
3000
0.721
0.58
10000
3000
0.712
0.51
15
CLOSURE
Numerical modeling has been conducted using different turbulence models in
conjunction with the Inter-Phase-Slip Algorithm (IPSA) to investigate the performance of
bottom water draw off concept. Results, in general, are insensitive to the different
versions of k-e models used. The simplest and less demanding model should be used. The
effects of bottom water draw-off flow rates on the quality of drawn-off water were
investigated. It was found that the water quality in the first pipe start to decrease as the
flow is increased beyond 5000 m3 / day . The water quality in the second pipe also
decreases continuously with the increase in the rate of water withdrawal from the first
pipe due to the increase in disturbances and mixing downstream of the draw-off pipe.
ACKNOWLEDGEMENTS
Financial support provided by Petroleum Development Oman under Contract (2001-27)
is gratefully acknowledged. Thanks go to the project mentor Mr Adil Al-Lawatya for
useful discussions.
REFERENCES:
Arirachakaran, S., Oglesby, K. D., Malinowsky, M. S., Shoham, O. and Brill, J. P.
(1989) An analysis of oil/water flow phenomena in horizontal pipes, SPE
Production Operations Symposium, Oklahoma, March 13-14 (SPE 18836).
Bessette, V.D. and Jepson, W.P. (1997), A segregated flow model to predict water
layer thickness in oil-water flows in horizontal and slightly inclined pipelines,
8th International Conference on Multi-Phase Flow, TE PRODUCTION.
Brauner, N. and Maron, D.M. (1989), Two-phase liquid-liquid stratified flow,
PhysicoChem. Hydrodynamics, vol. 11, no. 4, pp. 487-506.
Charles, M.E., Govier, G.W., Hodgson, G.W. (1961), The horizontal pipeline flow
of equal density oil-water mixtures, Can. J. Chemical Engineering, vol. 39, pp.
27-36.
16
Hall, A.R.W. and Hewitt, G.F. (1993), Application of two-fluid analysis to laminar
stratified oil water flows, Int. J. Multiphase Flow, vol. 19, pp. 711-717.
Khezzar, L. and Zurigat, Y.H. (2000), " CFD study of oil-water flow at a T-junction
for selective withdrawal,” 8th annual conference of the CFD conference of Canada,
Montreal, 11-13 June, 2000.
Kurban, A.P.A., Angeli, P., Mendes-Tatsis, M.A. and Hewitt, G.F. (1995),
“Stratified and dispersed oil-water flows in horizontal pipes”, 7th International
Conference on Multiphase Production, Cannes, France, pp. 277-291.
Oglesby, K.D. (1979), An experimental study on the effects of oil viscosity, mixture
velocity, and water fraction on horizontal oil-water flow, M.S. Thesis, U. Tulsa.
Russell, T.W.F., Hodgson, G.W. and Govier, G.W. (1959), Horizontal pipeline flow
of mixtures of oil and water, Canadian J. Chemical Engineering, February, vol.
37, pp. 9-17.
Shi, H., Cai, J. and Jepson, W.P. (2001), Oil-water two-phase flows in largediameter pipelines, ASME Transactions, J. of Energy Resources Technology,
vol. 123, no. 4, pp. 270-276.
Theron, B.E. and Unwin, T. (1996), Stratified flow model and interpretation in horizontal
wells, Proccedings of the 1996 SPE Annual Technical Conference and Exhibition,
Part Omega, Oct. 6-9, Denver, CO, USA, pp. 749-757.
Trallero, J.L., Sarica, C. and Brill, J.P. (1997), A study of oil/water flow patterns in
horizontal pipes, SPE Production and Facilities, vol. 12, no. 3, (August), pp.
165-172.
Zurigat, Y.H. and Khezzar, L. (2001), A numerical study of bottom water draw-off of
stratified oil-water pipe flow, Petroleum Science and Technology, vol. 19, no. 9-10,
pp. 1070-1088.
17
Appendix
Q1 File Listing
TALK=T;RUN( 1, 1)
************************************************************
Q1 created by VDI menu, Version 3.3, Date 03/05/00
CPVNAM=VDI;SPPNAM=Core
************************************************************
Echo DISPLAY / USE settings
************************************************************
IRUNN =
1 ;LIBREF = 302
************************************************************
Group 1. Run Title
TEXT(Bottom Water Draw off KEP Model V=1.646 )
************************************************************
Group 2. Transience
STEADY = T
************************************************************
Groups 3, 4, 5 Grid Information
* Overall number of cells, RSET(M,NX,NY,NZ,tolerance)
RSET(M,250,25,50)
* Set overall domain extent:
*
xulast yvlast zwlast
name
XSI= 9.500000E+00; YSI= 7.000000E-01; ZSI= 7.000000E-01
RSET(D,CHAM )
************************************************************
Group 6. Body-Fitted coordinates
************************************************************
Group 7. Variables: STOREd,SOLVEd,NAMEd
ONEPHS = F
NAME(150) =EPKE
* Solved variables list
SOLVE(P1 ,U1 ,U2 ,V1 ,V2 ,W1 ,W2 ,R1 )
SOLVE(R2 )
* Stored variables list
STORE(EPKE)
* Additional solver options
SOLUTN(P1 ,Y,Y,Y,N,N,Y)
SOLUTN(U1 ,Y,Y,Y,N,N,Y)
SOLUTN(U2 ,Y,Y,Y,N,N,Y)
SOLUTN(V1 ,Y,Y,Y,N,N,Y)
SOLUTN(V2 ,Y,Y,Y,N,N,Y)
SOLUTN(W1 ,Y,Y,Y,N,N,Y)
SOLUTN(W2 ,Y,Y,Y,N,N,Y)
SOLUTN(R1 ,Y,Y,Y,N,N,Y)
SOLUTN(R2 ,Y,Y,Y,N,N,Y)
TURMOD(KEMODL)
************************************************************
Group 8. Terms & Devices
18
UDIFF = T
UCONNE = T
USOURC = T
************************************************************
Group 9. Properties
SETPRPS(1, 67)
RHO1 = 9.982300E+02
PRESS0 = 1.000000E+05
TEMP0 = 2.730000E+02
CP1 = 4.181800E+03
RHO2 = 7.982300E+02
CP2 = 4.181800E+03
ENUL = 1.006000E-06
DVO1DT = 1.180000E-04
DVO2DT = 1.180000E-04
PRT (EP ) = 1.314000E+00
************************************************************
Group 10.Inter-Phase Transfer Processes
CFIPS = GRND7
RLOLIM = 1.000000E-03 ;CMDOT = 0.000000E+00
CFIPA = 1.000000E-03 ;CFIPB = 1.000000E-03
************************************************************
Echo PLANT settings
PLANTBEGIN
PLANTEND
************************************************************
Group 11.Initialise Var/Porosity Fields
FIINIT(R1 ) = 5.000000E-01 ;FIINIT(R2 ) = 5.000000E-01
FIINIT(EPKE) = 1.000000E+00
PATCH (VP1 ,INIVAL,5,0,0,0,0,0,1,1)
INIT(VP1 ,R1 , 0.000000E+00, 1.000000E+00)
PATCH (VP2 ,INIVAL,6,0,0,0,0,0,1,1)
INIT(VP2 ,R2 , 0.000000E+00, 1.000000E+00)
PATCH (OIL ,INIVAL,8,0,0,0,0,0,1,1)
INIT(OIL ,R2 , 0.000000E+00, 1.000000E+00)
INIADD = F
************************************************************
Group 12. Convection and diffusion adjustments
No PATCHes used for this Group
************************************************************
Group 13. Boundary & Special Sources
No PATCHes used for this Group
EGWF = T
************************************************************
Group 14. Downstream Pressure For PARAB
************************************************************
Group 15. Terminate Sweeps
LSWEEP = 1500
RESFAC = 1.000000E-03
************************************************************
19
Group 16. Terminate Iterations
LITER (R1 ) = 1 ;LITER (R2 ) = 1
************************************************************
Group 17. Relaxation
RELAX(P1 ,LINRLX, 1.000000E+00)
RELAX(U1 ,FALSDT, 1.000000E+00)
RELAX(U2 ,FALSDT, 1.000000E+00)
RELAX(V1 ,FALSDT, 1.000000E+00)
RELAX(V2 ,FALSDT, 1.000000E+00)
RELAX(W1 ,FALSDT, 1.000000E+00)
RELAX(W2 ,FALSDT, 1.000000E+00)
RELAX(R1 ,FALSDT, 1.000000E+00)
RELAX(R2 ,FALSDT, 1.000000E+00)
RELAX(KE ,LINRLX, 5.000000E-01)
RELAX(EP ,LINRLX, 5.000000E-01)
KELIN =
3
************************************************************
Group 18. Limits
VARMAX(U1 ) = 1.000000E+06 ;VARMIN(U1 ) =-1.000000E+06
VARMAX(U2 ) = 1.000000E+06 ;VARMIN(U2 ) =-1.000000E+06
VARMAX(V1 ) = 1.000000E+06 ;VARMIN(V1 ) =-1.000000E+06
VARMAX(V2 ) = 1.000000E+06 ;VARMIN(V2 ) =-1.000000E+06
VARMAX(W1 ) = 1.000000E+06 ;VARMIN(W1 ) =-1.000000E+06
VARMAX(W2 ) = 1.000000E+06 ;VARMIN(W2 ) =-1.000000E+06
VARMAX(R1 ) = 1.000000E+00 ;VARMIN(R1 ) = 1.000000E-06
VARMAX(R2 ) = 1.000000E+00 ;VARMIN(R2 ) = 1.000000E-06
************************************************************
Group 19. EARTH Calls To GROUND Station
USEGRD = T ;USEGRX = T
GENK = T
ASAP = T
************************************************************
Group 20. Preliminary Printout
ECHO = T
************************************************************
Group 21. Print-out of Variables
OUTPUT(P1 ,Y,Y,Y,Y,Y,Y)
OUTPUT(U1 ,Y,Y,Y,Y,Y,Y)
OUTPUT(U2 ,Y,Y,Y,Y,Y,Y)
OUTPUT(V1 ,Y,Y,Y,Y,Y,Y)
OUTPUT(V2 ,Y,Y,Y,Y,Y,Y)
OUTPUT(W1 ,Y,Y,Y,Y,Y,Y)
OUTPUT(W2 ,Y,Y,Y,Y,Y,Y)
OUTPUT(R1 ,Y,Y,Y,Y,Y,Y)
OUTPUT(R2 ,Y,Y,Y,Y,Y,Y)
************************************************************
Group 22. Monitor Print-Out
IXMON = 127 ;IYMON =
13 ;IZMON =
36
NPRMON = 100000
NPRMNT =
1
TSTSWP =
-1
************************************************************
Group 23.Field Print-Out & Plot Control
NPRINT = 100000
ISWPRF =
1 ;ISWPRL = 100000
No PATCHes used for this Group
20
************************************************************
Group 24. Dumps For Restarts
NOWIPE = T
GVIEW(P,0.000000E+00,-1.000000E+00,0.000000E+00)
GVIEW(UP,0.000000E+00,0.000000E+00,1.000000E+00)
STOP
21