Author(s): Nakayama Akihiko; Hisasue Nobuyuki
Linked Author(s): Akihiko Nakayama
Keywords: Intake flow; Surface vortex; HSMAC method; Large Eddy Simulation
Abstract: Three-dimensional unsteady flow with localized areas with large vortices in the intake channel of a small-scale model hydroelectric power station has been simulated numerically using a Large-Eddy Simulation (LES) technique. The method computes the fluctuating position of the free surface using a modified HSMAC iteration method. The standard Smagorinsky model with wall damping is used for the sub-grid scale model. With the total number of grid points of about one-third of a million (cid: 231) in the rectangular mesh, the near-wall flow is marginally resolved for the laboratory-scale Reynolds number, and complex and unsteady nature of the vortical flow can be reproduced reasonably well. Flow characteristics in the intake channel are known to be strongly influenced by the flow properties in the inflow plane, and the present calculation method is found to be able to reproduce the trends with respect to these inflow conditions. Surface vortex of weak intensity can be captured and the flow conditions associated with appearance of vortices can be examined based on the results of the present simulation.