Establishment And Application Study Of Numerical Wave Tank

There are several kinds of renewable energy resources in ocean, such as wind andwave energy. The numerical wave tank(NWT) is an important tool to evaluate securityperformance of artificial energy-harvesting devices in harsh marine environment. Bysolving Navier-Stokes equations directly, the NWT which combines the finite volumemethod(FVM) and the volume of fluid(VOF) method, can take fluid viscousity in consid-eration, andhastheabilitytosimulatesomecomplexprocessessuchaswavebreakingandwind-wave interaction. Adopting the numerical discretization method mentioned above,thispaperarchievedtwokindsofnumericalwavemakerutilizingsomeresultsofpotentialflow theory, and studied the movement of waves through the established NWT. A basicconnection was built between NWT and professional computional code of offshore windturbines, throuthwhichthefullynonlinearwave fromNWTwasapplied tocalculatewaveforces of offshore wind turbines.Firstly, the NWT was established and regular wave was simulated as a validation.Analytical results obtained by potential flow theory are used as theoretical basis for nu-merical wave maker. Velocity entry method and moving object method were used re-spectively to generate wave numerically. Artificial damping zone was used to eliminatewaveinremoteregion. Regularwavesweresimulatedinthetwo-dimensionalfinitelengthNWT. The velocity distribution of water was analyzed, which validated Wheeler stretch-ing method for the correction of velocity distribution under the wave crest.Secondly, the NWT with moving object wave-maker was further developed to com-plete the simulation and verification of irregular waves. A kind of wave breaking processwas simulated, which was a result of excessive water particle velocity when different fre-quency components of irregular wave was focused at some local region of wave surface.Thirdly, considering the joint wind-wave environment existed in nature, this papercarried on a preliminary discussion of wind-wave interaction between steady wind andregular wave. It was found that steady wind would reduce the amplitude of regular wave.A quantitative analysis was conducted for the phenomenon from the perspective of theuneven distribution of dynamic wind pressure on the wave surface.Finally, as an example of the combination for NWT and engineering applications,thefullynonlinearirregularwavewhichwasgeneratedbyNWT,wasappliedinthecalcu- lation of wave force on fixed single-pile-foundation offshore wind turbines. It was foundthat traditional wave model may underestimate the wave load on turbines structure.