dsd-nl 2014 - nghs flexible mesh - hkv lijn in water pilot impacts of grid refinements case side...
TRANSCRIPT
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Case side-channel Afferden-Deest
Impact of grid refinement
Deltares Software Dagen
Universiteit Twente: Erik ten Hagen, Suzanne Hulscher, Jord Warmink HKV lijn in water: Freek Huthoff, Joana Vieira da Silva, Andries Paarlberg Deltares: Aukje Spruyt, Arthur van Dam, Herman Kernkamp
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Contents
Part 1
• Test models
– Differences WAQUA - Delft3D - Flexible Mesh
Part 2
• Case Afferden-Deest
– Comparison Flexible Mesh - WAQUA
– Impact grid refinement
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test models
Simple rectangular model
– Comparison with analytical estimation
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test models
Simple rectangular model
– Comparison with analytical estimation
Test model Waal
– Differences WAQUA - Delft3D - Flexible Mesh in complex model
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Rectangular test model
• 2000x200 meter
• Horizontal bed (h=5.0 m) with sill (h = 5.3 m)
• Constant discharge upstream (1515 m3/s)
• Constant waterlevel downstream (11.70 m)
• Uniform roughness (Colebrook-White, k = 0.2 m)
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Rectangular test model
Analytical estimation:
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Rectangular test model
Chézy roughness using Colebrook-White:
Used in Delft3D and Flexible Mesh
Used in WAQUA
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Rectangular test model
Chézy roughness using Colebrook-White:
Used in Delft3D and Flexible Mesh
Used in WAQUA
Larger friction in Delft3D and Flexible Mesh!
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Rectangular test model
Results (Default settings)
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Rectangular test model
Colebrook-White formula of WAQUA in Flexible Mesh
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test model Waal
Differences WAQUA–Delft3D–Flexible Mesh for a
more complex model
– Schematization of 40 km Waal (Nijmegen – Tiel)
– Constant upstream discharge (16000 m3/s at Lobith)
– Constant downstream waterlevel (10.38 m +NAP)
– Friction
• Uniform Colebrook-White roughness (k = 0.2 m)
• Trachytopes (spatially variable and depth dependent roughness)
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test model Waal (Colebrook-White)
Results (default settings)
Maximum water level difference FM - WAQUA = 21.5 cm
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Conveyance2D
WAQUA
Flexible Mesh
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Weirs and dry points
Weirs
Dry points
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test model Waal (Colebrook-White)
Water level difference (Flexible Mesh – WAQUA)
Conveyance2D Colebrook-White
Overlaten Droge punten
Default settings FM FM X X
Overlaten FM FM X
Droge punten FM FM X
Bodeminstelling WAQUA FM X X
Colebrook-White FM WAQUA X X
Bodeminstelling + Colebrook-White
WAQUA WAQUA X X
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test model Waal (Trachytopes)
Results (default settings)
Maximum water level difference FM - WAQUA = 37.6 cm
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test model Waal (Trachytopes)
Waterlevel difference Flexible Mesh-WAQUA
Conveyance2D Colebrook-White
Overlaten Droge punten
Default settings FM FM X X
Bodeminstelling + Colebrook-White
WAQUA WAQUA X X
Overlaten WAQUA WAQUA X
Droge punten WAQUA WAQUA X
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Conclusion test models
• Large differences from bed and friction settings (Conveyance2D and Colebrook-White formula)
• Differences from modelling energy losses by weirs
• Use WAQUA setting for bed and Colebrook-White formula to compare Flexible Mesh with WAQUA
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Case Afferden-Deest
• Side-channel at Afferden and Deest (River Waal)
Bron: Rijkswaterstaat
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Case Afferden-Deest in WAQUA
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Research plan – comparison
Compare Flexible Mesh results with WAQUA
• Waalmodel without side-channel (reference) – Run Flexible Mesh with WAQUA-settings for design high
water wave (16000 m3/s at Lobith) and 1995 flood wave
– Compare Flexible Mesh with calibrated WAQUA model and 1995 measurements
• Waalmodel with side-channel – Run Flexible Mesh with WAQUA-settings for design high
water wave (16000 m3/s at Lobith) and 1995 flood wave
– Compare Flexible Mesh with WAQUA model
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Research plan – study area
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First results (comparison)
Waalmodel without side-channel (Pannerdense Kop)
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First results (comparison)
Waalmodel with side-channel (Pannerdense Kop)
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First results (comparison)
Waal without side channel
Waal with side channel
Pannerdense Kop 13.8 cm 17.6 cm
Nijmegen 9.1 cm 7.5 cm
Tiel 2.9 cm -0.8 cm
Water level difference Flexible Mesh - WAQUA
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First results (comparison)
Flow velocity (m/s) in side channel
WAQUA
Flexible Mesh
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Research Plan – Grid refinement
Assess impact grid refinement
• Waalmodel without side-channel (reference) – Refine grid Waal-channel at Afferden-Deest
– Determine when convergence is reached
• Waalmodel with side-channel – Refine grid side-channel Afferden-Deest
– Determine when convergence is reached
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Grid refinement
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Grid refinement
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Grid refinement
Example allignment
Bron: Herman Kernkamp, 2014
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Summary
• Differences from bed setting and Colebrook-White formula WAQUA settings used in
Flexible Mesh
• Higher water levels in Flexible Mesh
• Flexible Mesh solution for representation complex geometry
More accurate results for side-channel in
Flexible Mesh??