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Impacts from focused wave groups on monopiles
Monopile foundations for offshore wind turbines are subject to the harsh environment at sea. In this project extreme wave impacts are modelled in terms of focused wave groups. Wave components from a JONSWAP spectrum are linearly superimposed and matched in phase to hit the structure just at the time of breaking. The modelling is done with the OpenFOAM CFD solver.
Nonlinear waves with vorticity

Inclusion of vorticity in Boussinesq models.

Many water wave problems can be solved with good accuracy using potential flow theory. This simplifies the computational work considerably. For water waves, the socalled Boussinesq type models have shown great success in accurately modelling highly nonlinear and dispersive wave motion, yet reducing the original 3D problem to a 2D one.

Most Boussinesq models, however, are derived under the assumption of potential flow. Hereby, the effect of a shear current cannot be modelled. Also, the production of vorticity in breaking waves is not modelled.

In this project with Per Madsen and Hemming Schäffer, vorticity effects are included into the class of highly accurate Boussinesq models, developed at DTU over the last decade. 

Overtopping of Violent Individual Wave Impacts
The OVI project is a collaboration between me at Bristol University and Alison Hunt, Geoff Bullock and Ravi Jayaratne at Plymouth University. We are studying violent wave impacts and their overtopping over vertical and sloping walls. We make use of focused wave groups on the experimental side and compressible Euler equations plus Navier Stokes modelling on the numerical side.
Publications

Journal papers

H. Bredmose, A. Hunt-Raby, R. Jayaratne and G.N. Bullock (2010). `The ideal  flip-through
impact. Experimental and numerical investigation.' To appear in Journal of
Engineering Mathematics. Special commemorative volume for Howell Peregrine.

H. Bredmose, D.H. Peregrine and G.N. Bullock (2009). `Violent breaking
wave impacts. Part 2: Modelling the e ect of air'. To appear in Journal of Fluid
Mechanics.

G. N. Bulluck, C. Obhrai, D.H. Peregrine and H. Bredmose (2007). ‘Violent breaking
wave impacts. Part 1: Results from large-scale regular wave tests on vertical and sloping
walls’. Coastal Engineering. 54 (2007) pp 602–617.

H. Bredmose, Y. Agnon, P.A. Madsen and H.A. Schäffer (2004) ‘Wave transformation
models with exact second-order transfer’. European Jour. Mech./ B Fluids 24(6) pp
659–682.

H. Bredmose, H.A. Schäffer and P.A. Madsen (2004) ‘Boussinesq evolution equations:
Numerical efficiency, breaking and amplitude dispersion’. Coastal Engineering 51(11–
12) pp 1117–1142.

H. Bredmose, M. Brocchini, D.H. Peregrine and L. Thais (2003) ‘Experimental investigation
and numerical modelling of steep forced water waves’. J. Fluid Mech. vol 490,
pp 217–249.

J.H. Pihl, H. Bredmose and J. Larsen (2001) ‘Shoaling of sixth-order Stokes waves on a
current’. Ocean Engng. 28(6), pp 667–687.

 

Conference proceedings papers

M.O.L Hansen, H. Bredmose and S. Schløer (2011) ’Examples of important ongoing re-
search topics for o?shore wind energy’. 4th International Conference on Computational
Methods in Marine Engineering. Lisbon, Portugal, September 2011.

G. K. V. Ramachandran, H. Bredmose, J. N. Sørensen and J. J. Jensen (2011) ’Response
of a TLP ?oating wind turbine subjected to combined wind and wave loading’. 26th
Int. Workshop Water Waves Floating Bodies, Athens, Greece, April 2011.

S. Schløer, H. Bredmose and H.B. Bingham (2011) ’Irregular wave forces on monopile
foundations. E?ect of full nonlinearity and bed slope.’ Proc. 30th Int.. Conf. O?shore
Mech. Arctic Engng. Rotterdam, The Netherlands 2011. ASME.

H. Bredmose and N. G. Jacobsen (2011) Vertical wave impacts on o?shore wind turbine
inspection platforms. Proc. 30th Int. Conf. O?shore Mech. Arctic Engng. Rotterdam,
The Netherlands 2011. ASME.

H. Bredmose and N. G. Jacobsen (2010) ’Breaking wave impacts on o?shore wind turbine
foundations: Focused wave groups and CFD’. Proc. 29th Int. Conf. O?shore Mech.
Arctic Engng. Shanghai, China 2010. ASME.

G. Bullock and H. Bredmose (2010) ’Breaking wave impacts on coastal structures’. Proc.
5th Ann. Conf. Adv. Computing and Technology, University of East London.

A. Hunt-Raby, I.K. Othman, R. Jayaratne, G. Bullock and H. Bredmose (2009) 'Eff ect
of protruding roughness elements on wave overtopping'. Proc. Coasts, Marine Struct.
and Breakwaters, Edinburgh September 2009. Inst. Civ. Engng, UK.

E.D. Christensen, H. Bredmose and E.A. Hansen (2009) 'Transfer of Boussinesq waves
to a Navier-Stokes solver. Application to wave loads on an o ffshore wind turbine foundation'.
Proc. 28th Int. Conf. O shore Mech. Arctic Engng. Honululu, Hawaii 2009. ASME.

R. Jayaratne, A. Hunt-Raby, G.N. Bullock and H. Bredmose (2008) 'Individual violent
overtopping events: New insights'. 31st Int. Conf. Coast. Engng. Hamburg. ASCE.

H. Bredmose and G.N. Bullock (2008) ‘Scaling of wave-impact pressures in trapped air
pockets’. Proc. 23rd Int. Workshop on Water Waves and Floating Bodies, Korea, April
2008. 4pp.

H. Bredmose, D.H. Peregrine and A. Hunt (2007) ’Wave height? A study of the impact
of wave groups on a coastal structure’. Proc. 22nd Int. Workshop on WaterWaves and
Floating Bodies, Plitvice Lakes, Croatia, April 2007. 4pp.

 D.H. Peregrine, H. Bredmose, G.N. Bullock, A.C. Hunt and C. Obrhai (2006) ‘Water wave impact on walls and the role of air’. Proc. 30th Int. Conf. Coastal Engng., San
Diego 2006. ASCE.

H. Bredmose, J. Skourup, E.A. Hansen, E.D. Christensen, L.M. Pedersen and A. Mitzlaff
(2006) ’Numerical reproduction of extreme wave loads on a gravity wind turbine
foundation’. Proc. 25th Int. Conf. Offshore Mech. Arctic Engng. Hamburg 2006.
ASME.

G.N. Bullock, C. Obhrai, G.Müller, G.Wolters, D.H. Peregrine and H. Bredmose (2005)
‘Advances in the understanding of wave-impact forces’. Proc. of Int. Conf. Coastlines,
Structures and Breakwaters, 2005.

E.D. Christensen, H. Bredmose and E.A. Hansen (2005) ‘Extreme wave forces and wave
run-up on offshore wind turbine foundations’. Copenhagen OffshoreWind 2005.

D.H. Peregrine, H. Bredmose, G. Bullock, C. Obhrai, G. Müller and G. Wolters (2004).
‘Violent water wave impacts on walls and the role of air’. 29th Int. Conf. Coast. Engng.
Lisbon. ASCE.

G. Bullock, C. Obhrai, G. Müller, G. Wolters, D.H. Peregrine and H. Bredmose (2004).
‘Characteristics and design implications of breaking wave impacts’. 29th Int. Conf.
Coast. Engng. Lisbon. ASCE.

C. Obhrai, G. Bullock, G.Müller, G.Wolters, D.H. Peregrine, H. Bredmose and J. Grüne
(2004). ‘Violent wave impacts on vertical and inclined walls: large scale model tests’.
29th Int. Conf. Coast. Engng. Lisbon. ASCE.

H. Bredmose, D.H. Peregrine, G. N. Bullock, C. Obrhai, G.Müller and G.Wolters (2004)
‘Extreme wave impact pressures and the effect of aeration’, Proc. 19th Internat. Workshop
on Water waves and Floating Bodies, Cortona, Italy, 4pp.

G. Bullock, C. Obhrai, G. Müller, G. Wolters, D.H. Peregrine and H. Bredmose (2003)
‘Field and laboratory measurements of wave impacts’. Proc of the 3rd Coastal Structures
Conference, Portland, Oregon. ASCE.

H. Bredmose, D.H. Peregrine, A. Porter and G. Bullock (2003) ‘Wave impact and aerated
water’. Proc. 18th Int. Workshop onWater waves and Floating Bodies, Le Croisic,
France, 4pp.

H. Bredmose, P.A. Madsen, H.A. Schäffer and Y. Agnon (2002) ‘Fully dispersive evolution
equations: wave breaking and efficiency’. Proc. of 28’th Int. Conf. on Coastal
Engng., Cardiff, Wales. ASCE.

H. Bredmose, P.A. Madsen and H.A. Schäffer (2001) ‘Modelling of wave breaking in
Boussinesq evolution equations’. In ‘OceanWave Measurement and Analysis. Proc. of
theWaves 2001 Symposium, San Francisco, US’. ASCE.

H. Bredmose, P.A. Madsen and H.A. Schäffer (2000) ‘On the accuracy of Boussinesq
evolution equations’. Proc. of 27’th Int. Conf. on Coastal Engng., Sydney, Australia.
ASCE.

CV
full cv (pdf)

 

Education

2002 Ph.D. in Wave Hydrodynamics. Informatics and Mathematical Modelling
and Department of Mechanical Engineering, Technical University
of Denmark.

1999 M.Sc. in Engineering. Technical University of Denmark. Specialized
into Applied Mathematics and Hydrodynamics.

 

Employments

Jan 2011Present: Associate professor in Offshore Wind Energy. DTU Wind Energy (2012-present) and DTU Mechanical Engineering (2011).  Appointed within The Ocean Energy Research Program, a collaboration between Statkraft and the three universities of DTU, NTNU and Uppsala. Research within offshore wind energy. Project manager for the 'Wave loads' project with participation of DTU Wind Energy, DTU Mech. Engng and DHI.  Supervisor of 2 PhD projects on bottom fixed wind turbines and co-supervisor of a PhD project on floating offshore wind turbines. Coordinator of DTU activities within The Ocean Energy Research Program.  

Mar 2009Dec 2010: Assistant professor in Ocean Energy. DTU Mechanical Engineering.  Appointed within The Ocean Energy Research Program, a collaboration between Statkraft and the three universities of DTU, NTNU and Uppsala. Research within offshore wind energy. Co-supervisor of a Ph.D. project on floating offshore wind turbines. Coordinator of DTU activities within The Ocean Energy Research Program. 

Nov 2006 – Nov 2008: Post doctoral Research Assistant. School of Mathematics,
University of Bristol, UK and DTU. Research into overtopping at breakwaters and coastal
structures. Numerical modelling of individual overtopping events in close collaboration
with experimental work at University of Plymouth. Additional research on inclusion of vorticity
in Boussinesq-type wave models for improved wave breaking and wave induced circulations. 

Jan 2005 – Oct 2006: Research Engineer. DHI Water & Environment, Denmark. Modelling
of wave impacts on offshore wind turbine foundations using a 3D Navier-Stokes
solver. I developed a coupling allowing waves from a Boussinesq solver to be transferred
to this Navier-Stokes code. I was also involved in laboratory experiments, wave modelling studies and modelling of the stratified flow at a cooling water outlet.

Dec 2002 – Jan 2005: Post doctoral Research Assistant. School of Mathematics, University
of Bristol, UK. Numerical modelling of wave impacts on break waters, as part of
the BWIMCOST project. The work focused on the effect of entrained air on the impact
of waves. The work included offshore wave detection, nonlinear wave transformation
and compressible flow close to the break water.