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Steps towards fully nonlinear simulations of arrays of OWSC
Publikationstyp
Conference Paper
Date Issued
2016
Sprache
English
Author(s)
Institut
TORE-URI
Citation
19th Numerical Towing Tank Symposium (NuTTS 2016)
Contribution to Conference
OWSCs in waves reflect, refract and radiate waves in different directions depending on geometrical,structural and dynamic properties of the flap. Array interaction describes the changes induced on theexcitation of flaps in an array compared to the excitation of a single flap.Renzi and Dias, 2013, Renzi et al., 2014, investigated array effects of OWSCs using a linearised semi-analytical and a linearised FEM method. However, research suggests that the applicability of linear meth-ods for the simulation of OWSCs is limited to very small flap angles (Crooks et al., 2014, Crooks et al., 2016).Linear inviscid assumptions seem to break down in typical operating conditions (Folley et al., 2004,Asmuth et al., 2014).
It can therefore be assumed that the accuracy of linear methods in predicting the characteristic wave pat-tern around a flap and the interaction between multiple such devices is limited when applied to realisticoperating conditions with typical pitch motion amplitudes.Although RANS CFD tools have been shown to reproduce the motion of single flaps in waves within thelevels of experimental accuracy and can provide detailed data of all field variables like surface elevation,pressure or velocity (Schmitt and Els ¨asser, 2015a), the simulation of arrays of WECs remains an openchallenge. Due to numerical dissipation water waves simulated using volume of fluid methods tend todiminish in height and require careful spatial and temporal discretisation.The simulation of multiple moving bodies requires adaptation of the mesh and constitutes a considerablecomputational effort. As with physical test facilities numerical wave tanks require non-reflecting bound-ary conditions and wave makers.
It can therefore be assumed that the accuracy of linear methods in predicting the characteristic wave pat-tern around a flap and the interaction between multiple such devices is limited when applied to realisticoperating conditions with typical pitch motion amplitudes.Although RANS CFD tools have been shown to reproduce the motion of single flaps in waves within thelevels of experimental accuracy and can provide detailed data of all field variables like surface elevation,pressure or velocity (Schmitt and Els ¨asser, 2015a), the simulation of arrays of WECs remains an openchallenge. Due to numerical dissipation water waves simulated using volume of fluid methods tend todiminish in height and require careful spatial and temporal discretisation.The simulation of multiple moving bodies requires adaptation of the mesh and constitutes a considerablecomputational effort. As with physical test facilities numerical wave tanks require non-reflecting bound-ary conditions and wave makers.