Current Status of CAS Team on Task A Step 0: Model Inception
– two-phase flowtwo-phase flow modeling for the laboratory drying testmodeling for the laboratory drying test
By Xiaoyan Liu, Chengyuan Zhang and Quansheng Liu
Wuhan Institute of Rock and Soil MechanicsChinese Academy of Sciences (CAS)
October 20-23, 2008Wakkannai, Japan
DECOVALEX 2011
2nd workshop & Task A Force Meeting
Step 0: Identification of relevant processes and of Opalinus Clay
parameters. Modelling of the laboratory drying test.
Step 1: Hydromechanical modelling up to the end of Phase 1.
Step 2: Hydromechanical modelling up to the end of Phase 2 using
parameters backcalculated from step 1. Advanced features as permeability
anisotropy, rock damage and permeability increase in the damaged zone
may be considered.
Step 3: Hydromechanical and geochemical modelling of the full test.
Conservative transport and one species considered.
Step 4: Hydromechanical and geochemical modelling of the full test.
Reactive transport and full geochemical model (optional).
Task A Research programme
Step 0General model
description
Impermeable lateral boundaries
10cm
28cm
2/1.1
/51.0
%33
30
cmdaygpev
scmV
RH
CT
air
o
General model description
Governing Equations
Code developement
Simulation results
Discussion
Conclusion
Next steps
OutlineOutline
Based on three interacting continua
General model description multiphase system:General model description multiphase system:
Capillarity
Two-phase-flow
Liquid phase
Gas phaseVapour
Dry air
Phase exchange
Water
)(Kelg eej s
Governing Equations Governing Equations
For liquidFor liquid
phase exchangeevaporation or precipitation
lgjg
x
pkk
xt
ppp
s
Sil
j
l
l
lijrl
i
lavl
2/1 ))1(1( SSk rl
volume change changeretention curveretention curve
advection
Governing Equations Governing Equations
For vapourFor vapour
volume change change
j
aavv
vv
j x
MPMPMP
x
v
aavv
vv
av
v
MPMP
MP
mm
m
v
)( lg
gv
vatm
jgx
pkk
xDS
xt
ppp
s
S
t
p
pp
S
v
liv
j
v
v
vijr
jg
i
lavgvg
j
a
aavv
avv
j
v
aavv
vv
aavv
v
x
p
MPMP
MMP
x
p
MPMP
MP
MPMP
M
22
2
v0 p
1b
kk ijvij
v
3.212109.5p
TD
grg Sk
Klinkenberg parameter
phase exchange
ordinary diffusion
SlipKnudsen
effect
advectioncompressibilitycompressibility retention curveretention curve
0a
aagaa
aatm
ijv
ijr
jg
i
lavgg gx
pkk
xDS
xt
ppp
s
S
t
p
pp
S
Governing Equations Governing Equations
For dry airFor dry air
No phase exchange
CouplingCoupling schemescheme
(1) Phase exchange
(2) Saturation-Suction
(3) Different mobility (advection and diffusion effects) of two gas
Code DevelopmentCode Development
FEM solver FEM solver :: FRT-THMFRT-THM
(Developed for Task D of Decovalex-THMC)
FEBEX conception modelFEBEX conception model
Bentonitebuffer
Bentonitebuffer
Thermalexpansion
Thermalexpansion
Permeabilitychange
Permeabilitychange
SwellingSwelling
No boilingNo boiling
Unsaturated / Saturated
volcanic rock / crystalline
boiling / no boiling
no buffer / buffered
YMP DST / FEBEX
YMP DST conception modelYMP DST conception model
Permeabilitychange
Permeabilitychange
Drift with airDrift with airBoilingBoiling
Thermalexpansion
Thermalexpansion
Dry-outDry-out
(for Task A of Decovalex-2011)Modified FRT-THMModified FRT-THM
0.1m0.1m
D=0.1mD=0.1m
Step 0 Inception simulationStep 0 Inception simulation
Boundary conditionsBoundary conditions
FEM meshes: 3206 304FEM meshes: 3206 304
Geometry, Grid Design and Boundary Conditions
H=0.28mH=0.28m
Top
Bottom
Lateral
no flux
no flux
lp
vp
ap
freeseRH *
vatm pp
0.28m0.28m
vapour & air, no watervapour & air, no water
No-flux bNo-flux boundary oundary
forforwaterwater
vapourvapourdry airdry air
3D3D 2D2D
Variables & ParametersStep 0 Inception simulationStep 0 Inception simulation
(Munoz, 2001)
0.40 (in our work)
0.165
0 500 1000 1500 2000 2500 30000
10
20
30
40
50
60%
time /hour
B ExpGro1 fit of Data1_B
Boundary conditionRH = -20.06*exp(day*24/-686.624)+39.59
Step 0 Simulation resultsStep 0 Simulation results
pv time= 21 99 142 days
Dry air pressure pa
Vapour pressure pv
Total gas pressure pv+pa
142 days99
21
142 days
99
21
142 days
99 21
142 days99
21
Water pressure pl
Pressures profile
0 20 40 60 80 100 120 140 160
0.00
0.03
0.06
0.09
0.12
0.15
0.18
Wa
ter
loss
[K
g]
Time [days]
Sample A Sample B Sample C Calculated
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0.00
0.05
0.10
0.15
0.20
0.25
0.30
dis
tan
ce to
ba
se [m
]
Saturation
Comparison with Measured Data Step 0 Simulation resultsStep 0 Simulation results
0 1 2 3 4 5 6 7 8 9
0.00
0.05
0.10
0.15
0.20
0.25
0.30
dis
tan
ce
to
ba
se
[m
]
Water content [%]
time (d) 21 99 142
0 1 2 3 4 5 6 7 8 9
0.00
0.05
0.10
0.15
0.20
0.25
dist
ance
to b
ase
[m]
Water content [%]
time (d) 21 99 142
Comparison with calculation by (Munoz, 2001)
Step 0 Simulation resultsStep 0 Simulation results
by (Munoz, 2001)Our work
Comparison with calculation by (Munoz, 2001)
Step 0 Simulation resultsStep 0 Simulation results
0 20 40 60 80 100 120 140 1600.00
0.03
0.06
0.09
0.12
0.15
0.18
Wat
er lo
ss [K
g]
Time [days]
Sample A Sample B Sample C Calculated
by (Munoz, 2001)
Our work
Discussion (1) Discussion (1) Influence of relative permeability kInfluence of relative permeability krlrl
142 days
21 days
99 days
0.6 0.4 0.3 0.135
Discussion (2) Discussion (2) Influence ofInfluence of Relative Humidity (RH)
0 500 1000 1500 2000 2500 30000
10
20
30
40
50
60
%
time /hour
B ExpGro1 fit of Data1_B
0 20 40 60 80 100 120 140 160
0.00
0.05
0.10
0.15
0.20W
ate
r lo
ss [
Kg
]
Time [days]
RH slightly varying 33% constant
ConclusionConclusion
Simulation on the laboratory drying test seems good. Preliminary compare to test data and the calculation using code_bright show that they match well.
We must do more calibration and benchmark test on our model, especially to make sure the parameters are correct and model work well.
Next stepNext step
1. To consider coupled mechanical processes (swell & shrinkage effect; Damage of the material)
2. Step from 0 to 1.
Thank you for your attention