ESTIMATION OF ROTATION ANGLE AND CRITICAL VELOCITY OF MARIMOS DUE TO WAVES AND CURRENTS

Abstract

 Marimos, natural monuments of the country, are in danger of extinction, but the mechanisms of the formation of Marimos has not been understood. To clarify the mechanisms of the formation of Marimos, it is needed to estimate the rotation angle of Marimos due to wind waves and the critical velocity at which Marimos start moving. Therefore, we developed the Marimo model that consists of two different phase models, liquid and solid phases, by coupling a three-dimensional hydrodynamic model (Fantom) and a Distinct Element Method (DEM). The Marimo model has improved the reproducibility from the comparisons with laboratory experiments. The critical velocity is found to be the function of the Marimo radius, density and the bed conditions. In addition, it is revealed that random wave is one of the most significant factors for the rotation of Marimos.