ANALYSIS OF FLUID FLOW AROUND A GRAVEL BAG AND FLUID FORCES BY USING HYDRAULIC EXPERIMENTS

Abstract

 An open-channel flow experiments ware conducted on a model of a gravel bag to measure the flow field around the gravel bag and the fluid forces acting on it. The velocity and pressure distributions were measured at the upstream and downstream cross-sections of the gravel bag, revealing the flow characteristics around the gravel bag. Furthermore, using the measured velocity and pressure distributions at the upstream and downstream cross-sections, the fluid forces acting on the gravel bag were determined by considering the momentum balance. By comparing the estimated critical friction force, which considers buoyancy and lift, with the fluid forces obtained from the momentum balance, it was demonstrated the effectiveness of the measuring method of the fluid force by measuring the pressure distribution and considering the momentum balance. Additionally, it was confirmed that when measuring fluid forces based on the momentum balance, it is important to measure pressures that differ from the hydrostatic pressure distribution.