Study of the effect of Froude number on the free surface by fluid analysis

The two-phase flow simulation module interFoam of OpenFOAM was applied to a flow with a free-surface and the results were discussed. In this study, the flow simulation around a cylinder with a free surface placed perpendicular to the flow and whose upper part protrudes above the water surface was conducted. As a result, we could reproduce the phenomenon peculiar to the supercritical field, where the flow is no longer affected by the downstream flow when the Froude number exceeds 1. In particular, at the Froude number of 0.8, we could reproduce the phenomenon similar to the supercritical field, where the Froude number exceeds 1 at the water depth near the free surface due to the acceleration of the flow passed by the cylinder. At the simulation of a Froude number of 1.0, the flow behind the cylinder was different from the experiment. This is considered due to the low accuracy of capturing changes in the flow such as shock waves in the supercritical field. The behavior of the free surface due to the wettability of the cylinder surface is also considered to have an effect.