Long wave propagation and bore dynamics in coastal and estuarine environments

Transcription

1 IAHR-APD 2014 Keynote Lecture September 21-24, 2014, Hanoi Long wave propagation and bore dynamics in coastal and estuarine environments Philippe Bonneton EPOC, METHYS team, Bordeaux Univ., CNRS Sumatra 2004, tsunami reaching the coast of Thailand, Madsen et al. (2008)

2 Introduction non-hydrostatic processes 7 min 18 min 30 min 40 min a=2m 50 km Tissier, Bonneton et al., JCR2011 Tissier, Bonneton et al. (JCR 2011)

3 Introduction Applications Long waves and non-hydrostatic processes Tsunamis Tidal waves tidal bores 2011 great Tohoku tsunami; Naka river at Hitachinaka city Tidal bore, Bonneton et al. 2011

4 Introduction Applications Long waves and non-hydrostatic processes Nearshore wind waves Understanding of non-hydrostatic phenomena and breaking Development of efficient long-wave modelling approaches

5 Introduction Collaborations long wave modelling Eric Barthélémy LEGI, Grenoble Rodrigo Cienfuegos PUC, Santiago de Chile Marion Tissier TU Delft David Lannes ENS, Paris Fabien Marche I3M, Montpellier Mario Ricchiuto INRIA, Bordeaux Nha Trang project / MOST Vietnam / France Nguyen Trung Viet Water Resources University Dinh Van Uu, Hanoi University of Science Rafael Almar, J-P. Lefebvre IRD, France Natalie Bonneton, Philippe Bonneton EPOC, France

6 Outline Introduction Observation of non-hydrostatic processes tidal wave propagation and tidal bore formation Non-hydrostatic modelling Theoretical background A new approach Validations Conclusion and perspectives

7 Outline Introduction Observation of non-hydrostatic processes tidal wave propagation and tidal bore formation Non-hydrostatic modelling Theoretical background A new approach Validations Conclusion and perspectives

8 Observation of non-hydrostatic processes Tidal waves Large amplitude spring tide 10 th September 2010 La Reole Pk -67 Bonneton et al., 2011

9 Observation of non-hydrostatic processes Tidal waves Tidal bore: a fascinating hydrodynamic phenomenon observed worldwide Qiantang River China Tidal bore occurrence is strongly underestimated Garonne River see Bonneton et al., 2012, 2014 Kampar River Sumatra (Bono)

10 Observation of non-hydrostatic processes Tidal waves no tidal bore tidal bore ε = T R D 1 Garonne River, Bonneton et al., 2014

11 Observation of non-hydrostatic processes Tidal waves F r = c u gd 1 1 D 1 = A1 A h 1 Low intensity tidal bores Garonne River, Bonneton et al., 2014

12 Observation of non-hydrostatic processes Tidal waves F=1.08 F=1.24 low intensity tidal bore high intensity tidal bore most of the time this phenomenon is ignored in estuaries

13 Observation of non-hydrostatic processes Tidal waves Seine estuary Field site 100 km from the estuary mouth Bonneton et al., 2012

14 Observation of non-hydrostatic processes Tidal waves need to reassess tidal bore occurrence in meso and macro-tidal estuaries worldwide (including Asian & Pacific estuaries) high frequency measurements are required tidal bores play a significant role in estuarine ecosystems

15 Outline Introduction Observation of non-hydrostatic processes tidal wave propagation and tidal bore formation Non-hydrostatic modelling Theoretical background A new approach Validations Conclusion and perspectives

16 Non-hydrostatic modelling Theoretical background z z = ζ(x,t) d A λ c H ε = µ = A d d λ 2 µ 0.01 ε = O(1) ε = O(µ)

17 Non-hydrostatic modelling Theoretical background d0 µ = λ 0 2 << 1 ε = A 0 = O( 1) d Inviscid 3D incompressible irrotational Euler equations asymptotic expansion with respect to µ 0 ε=ο(1) Serre or Green Naghdi equations

18 Non-hydrostatic modelling Theoretical background Lannes and Bonneton (2009) b(x,y)

19 Non-hydrostatic modelling A new approach Reformulation of SGN equations kd 0 3 Bonneton, Chazel, Lannes, Marche and Tissier (2011)

20 Non-hydrostatic modelling A new approach Lannes and Marche (2014) have proposed a new formulation where the operator to invert is time independent a considerable decrease of the computational time!

21 Non-hydrostatic modelling A new approach Hybrid method non-breaking waves: SGN broken wave fronts and swash motions: NSWE

22 Non-hydrostatic modelling Validations Shoaling and breaking of regular waves over a sloping beach NSWE S-GN S-GN z (m) X (m) X (m) S-GN

23 Non-hydrostatic modelling Validations Shoaling and breaking of regular waves over a sloping beach z (m) X (m)

24 Non-hydrostatic modelling Validations Shoaling and breaking of regular waves over a sloping beach Validation with Cox (1995) experiments Breaking point L1 L2 L3 L4 L5 L6 Tissier et al., 2012 Experimental data Model prediction

25 Non-hydrostatic modelling Validations Undular bore propagation Laboratory experiments by Soares-Frazao et Zech (2002), Fr = 1.104

26 Non-hydrostatic modelling Validations Undular bore propagation Fr =1.10 Fr =1.37 Fr =1.20 Fr =1.40 Fr =1.25 Fr =1.50 Fr =1.35 Fr =1.90 t=24s

27 Non-hydrostatic modelling Validations Wave overtopping and multiple shorelines BARDEX II - HYDRALAB project Bonneton et al., 2013

28 Non-hydrostatic modelling Validations Wave overtopping and multiple shorelines BARDEX II - HYDRALAB project Bonneton et al., 2013

29 Non-hydrostatic modelling Validations Wave overtopping and multiple shorelines Solitary waves overtopping a seawall (Hsiao and Lin, 2010) Tissier et al., 2012

30 Non-hydrostatic modelling Validations Wave overtopping and multiple shorelines Solitary waves overtopping a seawall (Hsiao and Lin, 2010) Tissier et al., 2012

31 Non-hydrostatic modelling Validations Wave overtopping and multiple shorelines Solitary waves overtopping a seawall (Hsiao and Lin, 2010) Tissier et al., 2012

32 Non-hydrostatic modelling Validations Wave overtopping and multiple shorelines Hsiao et Lin (2010) COBRAS model SURF-GN 2D VOF model RANS equations K-ε

33 Non-hydrostatic modelling Validations Long wave propagation in the swash zone Truc Vert Beach 2001 Offshore wave conditions: θ 0, Hs=3 m, Ts=12 s Maximum surf zone width: 500 m Bottom topography and pressure sensor locations

34 Non-hydrostatic modelling Validations Long wave propagation in the swash zone Nha Trang project (Vietnam/France): high frequency and high resolution swash database see Almar et al. (IAHR-APD 2014)

35 Conclusion and perspectives non-hydrostatic and dispersive effects play a significant role in long wave dynamics in coastal and estuarine environments Sumatra tsunami 2004 Tidal bore Garonne 2010 need to reassess tidal bore occurrence in meso and macro-tidal estuaries worldwide (including Asian & Pacific estuaries) impact on estuarine ecosystems

36 Conclusion and perspectives A new approach for long wave modelling new mathematical formulation easy to implement in existing NSWE models hybrid approach SGN/NSWE wave transformation and wave breaking Development of Finite Element methods on unstructured grid Mario Ricchiuto (INRIA, Bordeaux)

37 Thank you for your attention