Modeling of Unsteady Flow in Curved Channel

Abstract

TO analyze unsteady flow in a curved channel, three‐dimensional equations describing the conservation of mass and momentum are transformed from a Cartesian coordinate system to a channel‐fitted coordinate system. This transformation allows the use of a simple reflection boundary to simulate the walls of a curved channel. Equations in channel‐fitted coordinates are then integrated over the depth to obtain a set of depth‐averaged two‐dimensional equations that are then solved using the MacCormack explicit finite‐difference scheme. The results of the mathematical model are compared for verification to experimental data obtained on a laboratory test facility. The agreement between the computed and measured water levels is satisfactory. However, the computed wave speed is slower than the measured wave speed when the flow is near critical conditions. Reflection technique works well, except in regions close to the entrance of a bend.