Arboleda, C.E.

Stratigaki, V.

Troch, P.

Arboleda Chavez, Carlos

Stratigaki, Vicky

Troch, Peter

Ghent University Academic Bibliography

Extension of the validation cases of a numerical model of the flow within the scour protection around monopile foundations

Open Marine Archive

88 
Poster presentation Competition poster 
Extension of the validation cases of a numerical model of the flow within 
the scour protection around monopile foundations  
Arboleda Carlos, Stratigaki Vasiliki and Troch Peter 
Department of Civil Engineering, Faculty of Engineering and Architecture, Ghent University, 
Technologiepark 60, 9052 Zwijnaarde, Belgium 
E-mail: carlosemilio.arboledachavez@ugent.be  
 
Currently, monopiles are the most used support structure for offshore based wind energy 
production units. As any structure embedded into the seabed, scour holes appear due the 
hydrodynamic action of waves and currents leading to a loss of stability. In order to counter the 
effect, the hydrodynamic conditions into the soil, scour protections are placed around the 
monopile. Nevertheless, the hydrodynamic conditions can also lead to the failure of the scour 
protection as stated in [1]. [2] concludes that a numerical model of the scour protection and the 
hydrodynamic conditions can predict the shear stresses within the scour protection. In [1], it is 
shown the lack of a model able to simulate the combined action of waves and currents and a 
full depth numerical flume for modeling the behavior of water around monopiles and within 
their respective scour protection made of rip-rap material is proposed. The latter numerical 
flume will be referred in this abstract as “the model”. In [1], the model has been validated and 
compared to the experimental and numerical results presented in [2]. This validation has been 
done for current conditions only. 
 
The model is developed using the OpenFOAM toolbox [3]. Wave generation/absorption as well 
as currents generation is performed using the module IHFOAM [4]. In the latter module, the 
incompressible Volume Averaged Reynolds Averaged Naviers Stokes - VARANS - equations are 
solved in a finite volume discretization. In order to deal with the multiphase (air, water) nature 
of the problem, the Volume of Fluid - VOF - method is employed, which allows using the same 
set of equations to solve the momentum balance in both phases, thus, speeding up the 
calculations. The scour protection is considered as a porous medium as performed in [2]. 
 
The current research provides an extension of the validation cases presented in [1] by further 
comparing the results of the numerical wave flume with the experimental results for different 
scour protection thicknesses (one, two and four protection layer thicknesses) in current 
conditions as presented in [2]. 
 
The comparison shows the robustness of the numerical model which is in good agreement with 
the experimental results for one, two and four layer thicknesses. In conclusion, the developed 
numerical current flume captures the horseshoe vortices penetrating the scour protection. 
 
Further research will focus on the sensibility analysis of the model to different parameters of 
the grid (cell size in the free surface, around the pile and the scour protection) and the porous 
medium approach (A, B, C coefficients in the Forchheimer equation). 
 
Acknowledgement  
The first author would like, to acknowledge his FWO (Research Foundation-Flanders, project 
number 3G052716) PhD. funding. 
 
  
89 
References  
[1] Arboleda C., Wu M., Troch P., Stratigaki V., 2018. Development and validation of a numerical 
model of scour protection around monopiles under currents. Scour and Erosion IX: 
Proceedings of the 9th International Conference on Scour and Erosion (ICSE 2018), November 
5-8, 2018, Taipei, Taiwan, CRC Press, October 10, 2018. 
[2] Nielsen A. W., Liu X, Sumer B. M., Fredsoe J. 2013, Flow and bed shear stresses in scour 
protections around a pile in a current, Coastal Engineering 72:20-38 
[3] Jasak H. 1996, Error Analysis and Estimation for the Finite Volume Method with Applications 
to Fluid Flows, PhD. Thesis, Imperial College, University of London 
[4] Higuera P. 2015, Application of Computational Fluid Dynamics to Wave Action on Structures, 
PhD. thesis, Universidad de Cantabria 
 
Keywords: Numerical modeling; Numerical validation; OpenFoam; IHFOAM; VARANS; Scour 
protection; Monopiles foundations; Wind energy 
  


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Extension of the validation cases of a numerical model of the flow within the scour protection around monopile foundations

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