EXPERIMENTAL STUDY ON THE EFFECT OF INITIAL SETUP ANGLE OF TSUNAMI DEBRIS OBJECT ON ITS MOTION

Abstract

 It has been reported that there is uncertainty in motion of a tsunami debris object on horizontal land, and the motion is highly affected by the initial condition of an object. This study aims to experimentally investigate the effect of the initial setup angle θ₀ of a rectangular object on its motion induced by a tsunami. An object which initially had a face inclined in tsunami flow could move laterally in the flow. The lateral movement also depended on an angle of the object in the flow, which was especially varied by object’s rotation in an initial phase after the object started to move. In the case of an object with θ₀ =30 degree, there was especially a case that an object moved in the direction of 16.7 degree from the initial position. The standard deviation of lateral movement was modeled with the flow-down distance multiplied by 0.04, independent of the initial angle. Two objects closely arranged each other showed different patterns of movement from a single object by their interaction.