Applications Of Kelvin Source In Ship Wave Problems And Predictions Of Ship Resistance

With the acceleration of globalization of world economy,Shipping plays an important role in it,and the requirements of the ship performance are also gradually improved.Improving the ship rapidity is the key to improve the ship’s energy efficiency,reduce the transportation costs and enhance the market competitiveness,thus an efficient and accurate way to predict the ship resistance is inevitable.In this thesis,the characteristic of wavelike disturbance of Kelvin source Green’s function and its integrand are explicitly analyzed,especially the Near-field disturbance and wavelike disturbance.It has great difficulties in numerical aspects because of the infinite multipliers and high-frequency oscillating behavior in the integrand of wavelike disturbance.Analytical expressions of integral of wavelike disturbance on the horizontal line segment and its partial derivatives are deduced in advance.As a result,the order of infinite multiplier and the amplitude of oscillation function decrease.The difficulties resulting from the oscillatory behavior of integral are solved,and a new accurate and efficient scheme for the integration of Green’s function on space lines and over panels is proposed.Based on Neumann-Kelvin theory,present approach combining boundary element method is outlined and the corresponding computing codes are developed.It is well applied to evaluate ship waves,wave drag,sinkage and trim for both Wigley Hull,Series 60 model and Wigley catamaran.Using the velocity distribution on the ship hull obtained in the ship wave problems,the local Reynolds numbers are calculated as well as the friction resistance.And the Viscous pressure resistance is evaluated by empirical formula.Finally,the total resistance of ships are obtained.The numerical results of models are validated by comparing them with experimental measurements.Present method is efficient and accurate to predict the total resistance of ship models.