water wave impact on rigid walls
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06/11/11
Water wave impacton rigid walls
BSc. R. Euser
Contents
● About Femto Egineering● Water wave impacts● Simulating water wave impacts
using Radioss SPH
About femto engineering
Company
About Software sales Consultancy
Engineering agency, offering both
consultancy and software for structural
analysis (>25 employees)
More than 12 years experience in CAEActive in BeNeLux
and Ukraine
Development of client specific software &
customization of Femap & Hyperworks
Partner of Siemens
Analysis software
Training
Support
FE-analysis
Product optimization
Certification
Outsourcing
Activities
Customers
Offshore projects
Water wave impacts
Applications
Offshore
Coastal
Piping
Automotive
About wave impacts
● Wave evolution● Surrounding structures● Wave pressure● Air bubbles (aeration)
Wave evolution
Breaking wave
Steepening wave
Stable wave
Crest
Trough
Crest
Air pocket
Trough
Trough
Crest
Surrounding structures
● Shape● Roughness● Stiffness
Wave pressure
P x=∫t before
t after
px , t d t
VelocityPressureVelocity
Wave Eye
Worst case
Pressure impulse
Air bubbles (aeration)
Positives:● Pressure
reduction● Damping
Negatives:● Longer impact
duration● Larger impact
areat = 0.0 ms t = 3.5 ms
“Evolution of the air cavity during a depressurized wave impact.”Lugni et al.
Simulating water wave impactsusing Radioss SPH
Contents
● Radioss CFD methods● Radioss SPH approach● SPH Simulations:
● 2D dam break correlation● 2D water wave impact on a rigid wall
● Conclusions
Radioss CFD methods
ALEArbitrary Lagrange Eulerian
SPHSmooth Particle Hydrodynamics
Radioss SPH approach
f xi =∑j
m j
jf x j W r ij , h
W r , h ={ 32h3 [ 23− rh
2
12 rh3] r≤h
14h32− rh
3
hr≤2h
Law Navier-Stokes Radioss SPH
Conservationof mass
Conservationof momentum
DiDt
=−i∑j
m j
juij∇W ij
D uiDt =−∑
jm j pi p ji j
ij∇W ijD uDt
=− 1 ∇ T
DDt =−∇ u
2D dam break correlation
Load case
3.55 m0.38 m
d
d 0
d 0=0.15md=0.018m
vgate=1.5m/s
0 0.1 0.2 0.3 0.4 0.5 0.6 0.70
0.5
1
1.5
2Gate velocity
t [s]
v [m
/s]
Radioss SPH model
30,225 particles
d particle=0.002m
Results
0.219 s 0.281 s 0.343 s
0.468 s0.406 s
=0.010
=0.010
0 1500300 600 900 1200
Pressure [Pa]
2D water wave impacton a rigid wall
Goal
Measure the effect of particle size on impact pressure
Load cases
Wave 1 Wave 2
0 2 4 6 8 10 12 14 16 18 20
-10
-5
0
5
10Acceleration vertical plate
t [s]
a [m
/s^2
]
0 2 4 6 8 10 12 14 16 18 20
-3-2-10123
Acceleration vertical plate
t [s]
a [m
/s^2
]
35 m
Sensors20x20 cm
Plate
15 m
15 m
Sensors20x20 cm
Plate
15 m
Models
Water particles
Detail A
Detail A
Model Particle size [m] Particle count
R1 0.2 3,750
R2 0.04 93,750
R3 0.02 375,000
Object Element type
Plate SPH
Rigid wall Shell
Water SPH
Sensors RBE2
Sensors
Impact measurement
P x=∫t before
t after
p x , t d tPressure impulse
P sensorz=∑T0
T1 F sensorhsensor d p
z ,TDTDiscretization
Load case T0 [s] T1 [s] DT [s]
Wave 1 11.1 11.7 0.001
Wave 2 8.1 8.4 0.001
Time interval
Results – Wave 1
0.0E+00 2.0E+04 4.0E+04 6.0E+04 8.0E+04 1.0E+050
2
4
6
8
10
12
14
Pressure Impulse
R1R2R3
PI [Pa s]
z [m
]
11.1 11.2 11.3 11.4 11.5 11.6 11.70.0E+00
2.0E+04
4.0E+04
6.0E+04
8.0E+04
1.0E+05
1.2E+05
1.4E+05
1.6E+05
Total Pressure
R1R2R3
t [s]
P [P
a]
t = 11.4 s t = 11.7 st = 11.1 s
R1
R2
R3
[m/s]
Results – Wave 2
0.0E+00 5.0E+04 1.0E+05 1.5E+05 2.0E+050
2
4
6
8
10
12
14
Pressure Impulse
R1R2R3
PI [Pa s]
z [m
]
8.1 8.15 8.2 8.25 8.3 8.35 8.40.0E+00
1.0E+05
2.0E+05
3.0E+05
4.0E+05
5.0E+05
6.0E+05
7.0E+05
Total Pressure
R1R2R3
t [s]
P [P
a]
R1
t = 8.1 s t = 8.3 s t = 8.4 s
R2
R3
[m/s]
Results discussion
● Fluid velocity● Fluid pressure● Total pressure (pressure peaks)● Pressure impulse
Conclusions
● Wave impacts:● Wave evolution● Surrounding structures● Impact pressure● Aeration
● Radioss SPH simulations:● 2D Dam Break correlation● 2D wave impacts
molslaan 1112611 rk delftT +31 (0) 15 285 05 80 F +31 (0) 15 285 05 81
www.femto.nlinfo@femto.nl
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