See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/329374530 Presentation Slides ICSE 2018 Presentation · November 2018 CITATIONS READS 0 89 3 authors: Mario Welzel Arndt Hildebrandt Technische Universität Braunschweig Leibniz Universität Hannover 14 PUBLICATIONS 24 CITATIONS 42 PUBLICATIONS 123 CITATIONS SEE PROFILE SEE PROFILE Torsten Schlurmann Leibniz Universität Hannover 144 PUBLICATIONS 1,123 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: Enabling Open Ocean Aquaculture - system design View project HyConCast View project All content following this page was uploaded by Mario Welzel on 03 December 2018. The user has requested enhancement of the downloaded file.
Local Scour Development and Global Sediment Redistribution around a Jacket-Structure in combined Waves and Current Mario Welzel, T. Schlurmann, A. Hildebrandt M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 1
Outline 1) Experimental Setup 2) Test Conditions 3) Bed topography 3D – Scans 4) Dimensionless areal – erosion /deposition 5) Volume differences for 0D and 1D node distance 6) Conclusion M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 2
1) Experimental Setup Wave basin length: 40m, width: 25m, active & passive wave absorption, JONSWAP spectra interacting with currents Q max = 5m 3 /s v max = 0.5m/s M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 3
3D Wave-Current Basin M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 4
1) Experimental Setup Miniature Echo-Sounder Sediment pit: - Length 8m - Width 6.6m local scour 3D Laser scanner global scour M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 5
2) Test Conditions Table 1. Test conditions (0D distance to seabed) Test H s T p U m U C KC U cw S max /D pile1 m s cm/s cm/s - - - 1 0.15 2.0 13.3 10.1 6.7 0.43 0.45 2 0.15 2.0 13.3 22.5 6.7 0.63 0.89 3 0.15 2.0 13.3 38.8 6.7 0.75 1.70 4 0.16 3.4 17.5 10.1 14.9 0.37 1.03 5 0.16 3.4 17.5 22.5 14.9 0.56 1.39 ; 𝐿𝐷 � 𝑉 � · 𝑈 𝑉 � � 𝑉 �� � 𝑉 � � 𝑉 � 𝐸 M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 6
2) Test Conditions Table 1. Test conditions (0D distance to seabed) Test H s T p U m U C KC U cw S max /D pile1 m s cm/s cm/s - - - 1 0.15 2.0 13.3 10.1 6.7 0.43 0.45 2 0.15 2.0 13.3 22.5 6.7 0.63 0.89 3 0.15 2.0 13.3 38.8 6.7 0.75 1.70 4 0.16 3.4 17.5 10.1 14.9 0.37 1.03 5 0.16 3.4 17.5 22.5 14.9 0.56 1.39 ; 𝐿𝐷 � 𝑉 � · 𝑈 𝑉 � � 𝑉 �� � 𝑉 � � 𝑉 � 𝐸 M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 7
3) Scour development over time Fig.1: Scour development of test 01-03 at the different positions around the pile M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 8
4) Equilibrium scour depth Fig.2: (Near) Equilibrium scour depth 𝑇 ��� for pile 1, with 𝑉 �� � 0 indicating waves only and 𝑉 �� � 1 indicating current only, compared with scour depths of Sumer & Fredsoe (2001) M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 9
3) Bed topography – 3D Scans 1A = 0.55 / 0.55m Test 03 Test 05 𝐆𝐣𝐡. 𝟐: Bed topography of test 03 and 05, in top view, global erosion and deposition M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 10
6) Dimensionless areal - erosion / deposition 𝑊 � 𝑎 · 𝐵 ����� 𝑜 · 𝐸 � � 𝑊 𝑊 ������� 𝑏 � � 𝑊 ���������� 𝑏 � 𝑊 �,� � � 𝑜 · 𝐸 � �,� � 𝑊 �,� 𝑊 ��� ⁄ 𝑏 � 𝑏 � Fig.2: Schematic sketch of increasing total areas 𝑏 � around the structure footprint for the example of 𝑏 �.� M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 11
4) Dimensionless areal - erosion / deposition 𝑊 � 𝑎 · 𝐵 ����� 𝑜 · 𝐸 � � 𝑊 𝑊 ������� 𝑏 � � 𝑊 ���������� 𝑏 � 𝑊 �,� � � 𝑜 · 𝐸 � 𝑊 �,� � 𝑊 �,��� 𝑊 �,� � � ⁄ ⁄ 𝑏 � 𝑏 � � 𝑏 ��� 𝑏 � Fig.4: Schematic sketch of increasing incremental areas 𝑏 � � 𝑏 ��� around the structure footprint for the example of 𝑏 �.� M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 12
6) Dimensionless areal - erosion / deposition �,� � 𝑊 �,� 𝑊 ��� ⁄ 𝑏 � 𝑏 � Fig.3: Global erosion / deposition volume 𝑊 � around the structure, for each total area M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 13
4) Dimensionless areal - erosion / deposition 𝑊 �,� � 𝑊 �,��� 𝑊 �,� � � ⁄ ⁄ 𝑏 � 𝑏 � � 𝑏 ��� 𝑏 � Fig.5: Global erosion / deposition volume 𝑊 � around the structure, for each incremental area 𝑏 � 𝑏 � ⁄ � 𝑏 ��� 𝑏 � ⁄ M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 14
4) Dimensionless areal - erosion / deposition 𝑊 �,� � 𝑊 �,��� 𝑊 �,� � � ⁄ ⁄ 𝑏 � 𝑏 � � 𝑏 ��� 𝑏 � Fig.5: Global erosion / deposition volume 𝑊 � around the structure, for each incremental area 𝑏 � 𝑏 � ⁄ � 𝑏 ��� 𝑏 � ⁄ M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 15
4) Dimensionless areal - erosion / deposition 𝑊 �,� � 𝑊 �,��� 𝑊 �,� � � ⁄ ⁄ 𝑏 � 𝑏 � � 𝑏 ��� 𝑏 � Fig.5: Global erosion / deposition volume 𝑊 � around the structure, for each incremental area 𝑏 � 𝑏 � ⁄ � 𝑏 ��� 𝑏 � ⁄ M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 16
4) Dimensionless areal - erosion / deposition 𝑊 �,� � 𝑊 �,��� 𝑊 �,� � � ⁄ ⁄ 𝑏 � 𝑏 � � 𝑏 ��� 𝑏 � Fig.5: Global erosion / deposition volume 𝑊 � around the structure, for each incremental area 𝑏 � 𝑏 � ⁄ � 𝑏 ��� 𝑏 � ⁄ M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 17
4) Dimensionless areal - erosion / deposition 𝑊 �,� � 𝑊 �,��� 𝑊 �,� � � ⁄ ⁄ 𝑏 � 𝑏 � � 𝑏 ��� 𝑏 � Fig.5: Global erosion / deposition volume 𝑊 � around the structure, for each incremental area 𝑏 � 𝑏 � ⁄ � 𝑏 ��� 𝑏 � ⁄ M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 18
4) Dimensionless areal - erosion / deposition 2A 2.6A Similar global scour extends: Rudolph et al. (2004) 𝑊 �,� � 𝑊 �,��� 𝑊 �,� � � ⁄ ⁄ 𝑏 � 𝑏 � � 𝑏 ��� 𝑏 � Fig.5: Global erosion / deposition volume 𝑊 � around the structure, for each incremental area 𝑏 � 𝑏 � ⁄ � 𝑏 ��� 𝑏 � ⁄ M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 19
4) Volume differences for 0D and 1D node distance Test 03 Test 05 𝐆𝐣𝐡. 𝟕: Bed topography of test 03 and 05, for 1D and 0D distance of nodes to the sea bed M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 20
5) Volume differences for 0D and 1D node distance 𝑊 ���� � 𝑊 �,� � 𝑊 �,� Fig.7: Volume differences in 𝑊 � of test 3 and 5 with 0D and 1D distance of the nodes to the sea bed M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 21
5) Volume differences for 0D and 1D node distance 𝑊 ���� � 𝑊 �,� � 𝑊 �,� 12% higher erosion volume Fig.7: Volume differences in 𝑊 � of test 3 and 5 with 0D and 1D distance of the nodes to the sea bed M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 22
6) Conclusions Dimensionless areal erosion and deposition volumes enable different assessment to analyze repeating erosion patterns around structures. Hydrodynamic transparent structure reveals significant global scours, distance between the piles ~14D. Dependent of the near bed structural blockage and disturbance. Volume difference 1D and 0D, up to 12% higher erosion rates M. Welzel ICSE Taipei, Taiwan - 07.11.2018 Seite 23
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