REEF3D : Open-Source Hydrodynamics Large Scale Wave Propagation Modeling for the Norwegian Coast with REEF3D

Transcription

1 REEF3D : Open-Source Hydrodynamics Large Scale Wave Propagation Modeling for the Norwegian Coast with REEF3D Hans Bihs, Associate Professor Arun Kamath, Post Doc Marine Civil Engineering Department of Civil and Environmental Engineering NTNU Trondheim, Norway 1

2 REEF3D : Open-Source Hydrodynamics - Developed at the Department of Civil and Environmental Engineering, NTNU Trondheim - Focus on: - Free Surface Flows - Wave Hydrodynamics - Wave Structure Interaction - Floating Structures - Open Channel Flow - Sediment Transport - Code written in C++ - Published under GNU GPL v3 2

3 Complex Free Surface Flows 3

4 Example: Dam Break 4

5 Governing Equations Incompressible RANS + U j i j apple ( + j i + g i the velocity averaged over time, is the fluid density, is the pressu Temporal Discretization: 3rd-order TVD Runge-Kutta Spatial Discretization: 5th-order WENO Pressure Solution: PJM Turbulence Modeling: RANS or LES 5

6 Numerical Wave Tank Γ(x).6.4 Γ(x) x R x R Wave generation one wavelength Working zone air water Numerical two wavelengths other available methods - active wave absorption (AWA) - Dirichlet wave generation Wave Input - regular waves - irregular and focused waves - wavemaker - wave reconstruction 6

7 Cartesian Grid Implementation of numerical algorithms is straightforward level set method is Eulerian complex geometries are possible with immersed boundary Ghostcell Approach: - no extra boundary treatment - works well with Parallelization with MPI - works well with immersed boundary GC GC 7

8 Grid Generation : Primitives 8

9 Primitives: OWT Jacket built from primitives: S S S S S S S S S S S S Waveslam Project S S S S S S S S S S S S S S S S

10 Breaking Wave Forces: Setup d =3.8 m 54. m 23. m 1. m 33. m 2.3 m Experiments: GWK (Irschik et al. 22) H=1.3 m T=4. s D=.7 m 15 million cells 1

11 Breaking Wave Forces: 2D Test 11

12 Breaking Wave Forces: 3D Test 12

13 Breaking Wave Force 1. numerical experimental η[m] t [s] Free Surface 15 numerical experimental F [N] 1 5 Wave Force t [s] 13

14 Coastal Structures / Porous Structures x (m) Version May 2, 217 submitted to Entropy of x (m) (a). s (b).2 s.25 VRANS-equations.15 - adapted for.5 level set method.5 - adapted for staggered grid x (m).2.15 (m) x (m) x (m) x (m) x (m) (a). s (d)(a) (b).6..2 s s (e) (c).8 (c).4.4 s s x (m) x (m).5.5 x (m) x (m).5.5 x (m) x (m) (d) (d).6.6 s s (g) (e) (e) s s (h) (f) 1.4 (f) s s x (m) x (m) x (m) x (m) x (m) x (m) (g) (g) s s (j) (h) 1.8 (h) 1.4s1.4 s (k) (i) (i) 1.6 s s figure 11. Comparison of free surface.15 profiles.15 for flow passing throu rock with water level of 25 cm x (m) x (m) (j) 1.8 (j) 1.8 s s x (m) x (m) Porous medium with Glass beads x (m) x (m) (k) (k) s s (l) 2.2 (l) 2.2 s s 14

15 Slide generated Impulse Wave / Tsunami 1. m.2 WG 4 WG 3 WG 2 WG m 2.46 m 1.85 m WG 7 WG 1 WG 6 WG 9 WG 5 WG 8.61 m wedge.91 m 3.7 m η[m].2 Wu [24] REEF3D WG m 2.73 m 1.39 m 1.77 m 2.15 m η[m] t [s] WG9.2 Wu [24] REEF3D t [s] η[m].2 Wu [24] REEF3D WG t [s] 15

16 Sediment Transport Z Axis L=128 m 2.2 X Axis L=4.4 m s(m) Y Axis Y Axis s(m) Sediment Algorithm Y Axis s(m) (a) Full-sized NWT, L= 28 m 2 (b) Reduced-length NWT, L= 4.4 m Bed: Interface between Water and Solid better not to move grid level set function: Implicit Topology Technique Van Rijn: Bedload and Suspended Load Erosion/Deposition: Exner decoupling of temporal scales flow/sediment L=128 m L=128 m (a) Full-sized NWT, L= 28 m Validation (a) Full-sized NWT, L= 28 m y(m) 1 x(m) y(m) 1 x(m) Experiment: Sumer and Fredsøe (1992) (c) Zoom in view of the scour for L= 28 m regular waves, KC = (d) Zoom in view of the scour for L = 4.4 m Numerical Experiment.3.3 Numerical Experiment S/D S/D T* = g(s-1)d35 t/d x(m) x(m) 1.5.5* y(m) y(m) T =.5 g(s-1)d35 t/d

17 Pipeline Scour: Waves 17

18 Seawall Scour (a) t = 2s (b) t = 12s t = 2 s -.m (c) t = 17s.17m Intial profile Experiment, Fowler (1992) Simulated, REEF3D 5.m (d) -.m m -.2m.4 -.4m.6 -.6m.2m 2.5m m L(m) 3 L (m)

19 Seawall Scour : Close-up 19

20 Complex Geometry: STL File feet km 4 1 2

21 Open Channel Flow: Hydropower Spillways 21

22 Free Floating Box heave surge 22

23 REEF3D : Open-Source Hydrodynamics high low Model Dimensions Turbulence Br. Waves Detail REEF3D : CFD 3D yes yes REEF3D : NSEWAVE 3D yes no Speed low REEF3D : SFLOW 2D yes no high 23

24 Why expand REEF3D? - all scales of the physics can be considered - CFD requires well defined boundary conditions - REEF3D: accurate, stable, fast and parallel algorithms - modular C++ code / reusable algorithms - fully coupled domain decomposition - possible under HPC conditions - consistent user experiences - same geometry input everywhere 24

25 Why expand REEF3D? @x Z d Z d vdz = t[s] Linear Waves - NWT L = 2 - water depth d =.5m - wave height H =.2m - wave length L = 2m dx =.1m -> 5 cells / water depth REEF3D : NSEWAVE, dx =.1m REEF3D : CFD, dx =.1m x [m] 25

26 E39: Ferry-Free Coastal Highway E39: Kristiansund to Trondheim - 11km - 8 ferries - Challenges: - deep and wide fjords - example: Sognefjord - 37 m wide - 13 m deep Wave Modeling Challenges - deep water conditions - irregular coast line - many small islands - irregular bathymetry 26

27 Natural Topography - Mehamn Harbor 27

28 Natural Topography: Mehamn 176mx 144mx 15m 28

29 Natural topography: Andenes Andenes, Vesterålen, Norway 29

30 Natural Topography: Andenes (3D-NSEWave) H=1m, T=18s 325mx 18mx 53m 3

31 Conclusions REEFD and CFD in general have a huge potential for hydraulic, coastal and marine engineering waves current turbulence sediment transport stratification wave-structure-interaction (6DOF) Integrated approach: In-house competence for numerical methods, programming and physics Moore s Law: computer speed doubles each year possibilities for computational modelling exponentially increase over time 31