WP3 : Flood PropagationWP3 : Flood PropagationComputation On The ‘Isolated Computation On The ‘Isolated

Building Test Case’ And The ‘Building Test Case’ And The ‘Model Model City Flooding Experiment City Flooding Experiment ’’

B. Noël, Soares S., Y. ZechUniversité catholique de Louvain

IMPACT - 3rd Workshop Novembre 2003

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OverviewOverview

• Numerical Model• The ‘Isolated Building Benchmark’

– Numerical modelling– Numerical results– Sensitivity analysis

• The ‘Model City Benchmark’– Numerical modelling– Numerical results– Sensitivity analysis

IMPACT - 3rd Workshop Novembre 2003

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OverviewOverview

• Numerical Model• The ‘Isolated Building Benchmark’

– Numerical modelling– Numerical results– Sensitivity analysis

• The ‘Model City Benchmark’– Numerical modelling– Numerical results– Sensitivity analysis

IMPACT - 3rd Workshop Novembre 2003

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Numerical ModelNumerical Model

• 2D finite-volume method• First-order scheme• Flux evaluated by Roe’s scheme• Non-Cartesian grids allowed

‘Soares Frazão S., 2002 PHD Thesis ’

IMPACT - 3rd Workshop Novembre 2003

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OverviewOverview

• Numerical Model• The ‘Isolated Building Benchmark’

– Numerical modelling– Numerical results– Sensitivity analysis

• The ‘Model City Benchmark’– Numerical modelling– Numerical results– Sensitivity analysis

IMPACT - 3rd Workshop Novembre 2003

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The ‘Isolated Building The ‘Isolated Building Benchmark’Benchmark’

• Numerical modelling (2-mesh grid)– Grid :

Square meshes

Quadrangular meshes

IMPACT - 3rd Workshop Novembre 2003

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The ‘Isolated Building The ‘Isolated Building Benchmark’Benchmark’

• Numerical modelling– Building neighbouring

IMPACT - 3rd Workshop Novembre 2003

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The ‘Isolated Building The ‘Isolated Building Benchmark’Benchmark’

• Numerical modelling– Grid mean size : 5 x 5 cm– CFL number : 0.9–Time duration : ± 2 h– CPU : AMD XP1800+ (128Mb)

IMPACT - 3rd Workshop Novembre 2003

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The ‘Isolated Building The ‘Isolated Building Benchmark’Benchmark’

• Numerical results

IMPACT - 3rd Workshop Novembre 2003

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0

0.05

0.1

0.15

0 5 10 15 20 25 30t [s]

Zw

ate

r [m

]

G1 - experimentG1 - numerical

The ‘Isolated Building The ‘Isolated Building Benchmark’Benchmark’

• Numerical results– Water level :

IMPACT - 3rd Workshop Novembre 2003

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The ‘Isolated Building The ‘Isolated Building Benchmark’Benchmark’

• Numerical results– Water level (t = 10 s) :

IMPACT - 3rd Workshop Novembre 2003

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The ‘Isolated Building The ‘Isolated Building Benchmark’Benchmark’

• Numerical results– Velocity field (t = 5 s) :

Numerical ExperimentalNoël, Spinewine 2003 - UCL

IMPACT - 3rd Workshop Novembre 2003

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The ‘Isolated Building The ‘Isolated Building Benchmark’Benchmark’

• Numerical results– Velocity Intensity (t = 5 s) :

Numerical ExperimentalNoël, Spinewine 2003 - UCL

IMPACT - 3rd Workshop Novembre 2003

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Water Level at G2

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0 5 10 15 20 25 30

t [s]

h [

m]

Experimentn = 0.008n = 0.01n = 0.012

The ‘Isolated Building The ‘Isolated Building Benchmark’Benchmark’

• Sensitivity analysis– Manning roughness coefficient

IMPACT - 3rd Workshop Novembre 2003

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The ‘Isolated Building The ‘Isolated Building Benchmark’Benchmark’

• Sensitivity analysis– Initial downstream water-depth

Water Level at G2

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0 5 10 15 20 25 30

t [s]

h [

m]

Experimenth0 = 0.0mh0 = 0.01mh0 = 0.02m

IMPACT - 3rd Workshop Novembre 2003

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OverviewOverview

• Numerical Model• The ‘Isolated Building Benchmark’

– Numerical modelling– Numerical results– Sensitivity analysis

• The ‘Model City Benchmark’– Numerical modelling– Numerical results– Sensitivity analysis

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical modelling (channelled)

Mesh XXX

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical modelling (10-mesh grid)

Mesh XXX

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical modelling (original)

Mesh XXX

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical modelling (10-mesh grid)

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical modelling– Topography reconstruction

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical modelling– Upstream reservoir

• Dimensions : unknown but seen on picture

about 1 meter of longitudinal length

lateral bed level similar to the bed level of upstream end of channel

• Best way to model : decrease bed level of feeding tank and fill it with water at rest

numerical crash at corner of reservoir

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical modelling– Upstream reservoir

• bed level of the upstream end of channel• Inlet introduced at the upstream end of the

prolonged channel

Inlet

Walls

Walls

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical modelling– Grid mean size : 2.5 x 2.5 cm– CFL number : 0.1– Time duration : ± 5h.– Computer : AMD XP1800+ (128Mb)

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical results– Test cases 1a & 1b (t = 20 s) :

Staggered layer :

- velocity decreased

- water level increased in the building layer

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical results– Test cases 2a & 2b (t = 20 s) :

Staggered layer :

- velocity decreased

- water level increased in the building layer

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical results– Test cases 3a & 3b (t = 20 s) :

Low inflow :

60 l/s

High inflow :

100 l/s

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical results– Test cases 4a & 4b (t = 20 s) :

Buildings as bed elevation (15 cm):

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Numerical results– Test cases 4a & 4c (t = 20 s) :

High friction

(n = 10 s/m1/3):

- water lost in buildings

- maximum water level moves downstream and is a few decreased

IMPACT - 3rd Workshop Novembre 2003

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The ‘Model City Benchmark’The ‘Model City Benchmark’

• Sensitivity analysis– Downstream boundary condition

Water Level at G10

0

0.005

0.01

0.015

0.02

0.025

0 10 20 30 40 50 60

t [s]

h [

m]

average slopezero slope

WP3 : Flood PropagationWP3 : Flood PropagationComputation On The ‘Isolated Computation On The ‘Isolated

Building Test Case’ And The ‘Building Test Case’ And The ‘Model Model City Flooding Experiment City Flooding Experiment ’’

B. Noël, Soares S., Y. ZechUniversité catholique de Louvain