EXPERIMENTAL STUDY ON THE MOVEMENT PROCESS OF PUMICE STONE RAFTS IＮ SHALLOW WATER

Abstract

 When a volcanic eruption occurs, volcanic debris with pumice falls throughout the surrounding area. In coastal areas, including rivers, large amounts of pumice drift on the sea surface for extended periods causing various problems. However, there have been few studies on the migration process of pumice in shallow water due to the difficulty of quantifying its physical properties and reproducing the process because of its long-term suspension. In this paper, (1) the trajectory of pumice in a wave field and (2) the flow around a structure are investigated using a big wind tunnel tank. As a result, it was found that the trajectory of pumice swarms due to waves is suppressed or enhanced depending on the location. Moreover, the velocity of pumice movement and flow rate around structures are greatly affected by wind velocity.