Unsteady Viscous CFD Simulations of KCS Behaviour and Performance in Head Seas

Abstract

It is critical to be able to estimate a ship’s response to waves, since the added resistance and loss of speed may cause delays or course alterations, with consequent financial repercussions. Traditional methods for the study of ship motions are based on potential flow theory without viscous effects. Results of scaling model are used to predict full-scale of response to waves. Scale effect results in differences between the full-scale prediction and reality. The key objective of this study is to perform a fully nonlinear unsteady RANS simulation to predict the ship motions and added resistance of a full-scale KRISO Container Ship. The analyses are performed at design speeds in head waves, using in house computational fluid dynamics (CFD) to solve RANS equation coupled with two degrees of freedom (2DOF) solid body motion equations including heave and pitch. RANS equations are solved by finite difference method and PISO arithmetic. Computations have used structured grid with overset technology. Simulation results show that the total resistance coefficient in calm water at service speed is predicted by 4 .68% error compared to the related towing tank results. The ship motions demonstrated that the current in house CFD model predicts the heave and pitch transfer functions within a reasonable range of the EFD data, respectively.

Numerical Simulation of the Ship Resistance of KCS in Different Water Depths for Model-Scale and Full-Scale

“…In the process of the towing simulation, the attitude (pitch and heave) of a KCS always changes with the pressure distribution on the hull surface, hence the need for the 6-DOF equations [25]. The equations involve a time item; therefore, the unsteady RANS equation was solved with the 6-DOF system integrated into the solution program.…”

“…in which, S C is the benchmark numerical result from Equation (25). The validation uncertainty U V is given by:…”