極浅水域における横移動船舶に作用する流体力の特性変化に関する研究

摘要

近年の急速な船舶の大型化は，港湾内を航行する船舶の水深/喫水比H/dを著しく低下させ,想定していなかった大きな操縦特性の変化をもたらすことがある.本研究では，浅水域を航行する船体に作用する流体力特性，特に低速横移動船舶の横力特性の極浅水域での挙動について，実験と数値シミュレーションにより，流体力学的なメカニズムを含めた解明を目指した.%The behavior of hydrodynamic forces acting on a ship at lateral motion was investigated. Force measurement in towing tank and numerical simulation on viscous flow field were made, and correlations of hydrodynamic forces with flow field around ships were examined. A large flow pattern change at extreme shallow water case such as H/d＜1.20 was observed in model scale, and it causes serious characteristics change of lateral force. Present characteristics change could be caused by the pressure loss at the gap between sea bottom and ship bottom, which may be referred by 'retaining effect', and that generates the upstream flow pattern and separation pattern change.