樹木群を有する直線開水路流れにおける大規模水平渦の特性

Abstract

The present paper is concerned with large scale vortices developing along the interface between main flow and vegetated zone in a prismatic open channel. Two types of flume experiment and LES are carried out to clarify the evolution of large vortices and to discuss the vegetation modeling. In one experiment a continuous vegetation belt stands along the centerline of the channel whereas in the other experiment patched vegetation zones are installed along the channel centerline. Flow visualization is followed by measurement of water levels and three velocity components. It is demonstrated that a row of large vortices is produced along the edge of the vegetation belt and that the large vortices survive over the gap region between the vegetation zones with active lateral mixing. LES employing the concept of vegetation density shows that it can reasonably reproduce the flow field in the vegetation zones and that further refinement is necessary for the better prediction of the flow downstream of the patched vegetation zones.