Research On The Real-time Forecasting Method For Long Crest Random Wave And Ship Deterministic Motion

Ocean development need to rely on the ship and ocean engineering structures,they are by the action of waves are generated when motion at sea,excessive motion for operation safety of ship and ocean engineering structures a threat.Therefore decisions,people working in the Marine environment and its wave caused by the motion of the structures is the very important reference basis for operating decision,based on this,advance forecast outside the wave field and ship motion,the offshore operation decision-making,improve the working efficiency,avoid dangerous situation is critical.Based on the deterministic wave forecast,this paper establishes the real-time forecasting method of ship motion with the real-time computing technology of ship motion.The research work mainly includes the following aspects:Firstly,a comprehensive introduction to the current deterministic wave prediction theory and its motion forecast is carried out.According to the different classification basis,the deterministic wave forecast is classified.The key technical points of deterministic wave prediction are summarized,including wave field analysis technique,wave propagation velocity determination,wave field reconstruction technique and prediction range expansion technology.Second,the concept of deterministic wave forecasting and introduces the basic theory,its algorithm process is given,and gives a deterministic wave forecast of space theory forecast range,and sums up the premise condition of certainty wave forecasting,improved the existing can forecast based on spectral energy criteria,put forward a kind of form is more simple criteria based on amplitude,.Thirdly,based on numerical simulation and pool test,the deterministic wave forecast is studied comprehensively.The accuracy and reliability of deterministic wave prediction are proved,and the influence of sampling interval is analyzed.And deterministic prediction features of wave conducted in-depth research,forecast is given distance,measuring the length,forecast the relationship between the length of time,studied the forecast in advance at the same time,the calculation and analysis its characteristics on the wave of five to seven sea condition forecast.This paper introduces and discusses the abnormal point phenomenon which is lower than normal in the long term.Fourthly,the real-time solution method of ship transient motion response under wave excitation is introduced.Using RAO as a quick calculation method,the feasibility of this method is verified by the calculation error and the correlation of the results.On this basis,combining with the certainty of wave forecast,established the ship motion real-time forecast system for a long period of time,through the test of the four to six levels of sea condition forecast effect is analyzed,from the Angle of the prediction error,and forecast the correlation verifies the correctness of this method.It is found that the wave with poor prediction quality also has good adaptability.Fourthly,some prospects are put forward for some technical problems and theoretical defects in wave field analysis and wave acquisition.