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Two-Fluid Effective-Field Equations
and are void fraction function, with 1g l g l
2
2
( ) ( )0
( ) ( )( )
( ) ( )
( ) ( )0
( ) ( )( )
( ) ( )
g g g g g
g g g g g gg
g g g g g g
g
g
l
l
g
l l l l l
l l l l l ll
l l l l l l l
u
t x
u up
t x
E u H
t x
u
t x
u up
t
p
pt
px
Ep
H
t t
u
x
Mathematical Issues
• Non-conservative: – Uniqueness of Discontinuous solution?– Pressure oscillations
( ) ( )i ik kp p
• Non-hyperbolic system: Ill-posedness?– Stability– Uniqueness
• How to sort it out?
2
2
( )
( )
( ) ( )0
( ) ( )( )
( ) ( )
( ) ( )0
((
) ( )) )(
( )
g g g g g
g g g g g gg
g g g g g g g
l l l l l
l l l l l ll
l l l
vmg
i vmg
vm
g
l g
gp
p
u
t x
u up
t x
E u H
t x
u
t x
u
f
u f
fu
pt x
t
p
p p
p
E
t
( )
( ) i vmg
l l ll lufp u
xp
t
H
Remedy for hyperbolicity: Interfacial pressure correction term and
virtual mass term
Modeling – Interfacial Pressure (IP)
* 2g l g l
g l l g
p w
gl uuw Stuhmiller (1977):
2** wCp gp
Here, we have
1* pC
Faucet Problem: Ransom (1992)
• Hyperbolicity insures non-increase of overshoot, but suffering from smearing
• Location and strength of void discontinuity is converged, not affected by non-conservative form
Effect of hyperbolicity Solution convergence
0 2 4 6 8 100.0
0.1
0.2
0.3
0.4
0.5
0.6
C*
P=0
Vo
id F
ract
ion
X
0 2 4 6 8 10
0
20
40
60
80
100 C*
P=0
Ga
s V
elo
city
( m
/s)
X
0 2 4 6 8 100.0
0.1
0.2
0.3
0.4
0.5
0.6
C*
P=0
C*
P=1.0
Vo
id F
ract
ion
X
0 2 4 6 8 10
0
20
40
60
80
100 C*
P=0
C*
P=1.0
Ga
s V
elo
city
( m
/s)
X
Results for Toumi's shock tube problem. Interfacial correction terms only.
7
7
Initial condition: 1.0 10 pa, 0.25
2.0 10 pa, 0.10
L L
R R
p
p
Modeling – Virtual Mass (VM)
Drew et al (1979)
( )cvm vm vmd c dc cd dvmd
u u uuf u ut x
Cx
VM is necessary if IP is not present, the coefficients are
unreasonably
high for droplet flows.
Requirement of VM can be reduced with IP.
0 2 4 6 8 100.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
C*
P=0
Vo
id F
ract
ion
X
0 2 4 6 8 10
0
20
40
60
80
100 C*
P=0
Ga
s V
elo
city
( m
/s)
X
0 2 4 6 8 100.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
C*
P=0
C*
P=2.0
Vo
id F
ract
ion
X
0 2 4 6 8 10
0
20
40
60
80
100 C*
P=0
C*
P=2.0
Ga
s V
elo
city
( m
/s)
X
Results for Toumi's shock tube problem. With virtual mass model (Type II, = 0.4).vmC
7
7
Initial condition: 1.0 10 pa, 0.25
2.0 10 pa, 0.10
L L
R R
p
p
Numerical Method
• Extended from single-phase AUSM+-up (2003).
• Implemented in the All Regime Multiphase Simulator
(ARMS).
- Cartesian.
- Structured adaptive mesh refinement.
- Parallelization.
A case with 40% liquid fraction
Ugas=1km/s
L=0.4, liquid mass =400kgVL=150m/s(in radial)Liquid area: l=2m, r=0.4m
L=60m
R=12m
Axis
( Grid size 10cm, calculation time :0-150ms Calculation domain:,L=60m,R=12m )
Liquid fraction, pressure and velocity contours of particle cloud for time 0-150 ms.
Lquid fraction (Min:10-8 -Max:10-3)
Pressure (Min:1bar-Max:7bar)
Gas Velocity (Min:0m/s -Max:1,000m/s)
Droplet radius R = 3.2mm, incoming shock speed M = 1.509
Current and future works
• Complete the hyperbolicity work on the multi-fluid system.
• Complete the adaptive mesh refinement into our solver –
ARMS
• Expand Music-ARMS to solve 3D problems.
• Introduce physical models:
•Surface tension model
•Turbulence model
• Verification and validation.
• Real world applications.