Analysis of Flow in a Curved Channel Using the Curvilinear Orthogonal Numerical Mesh

Along the flow in a curved channel, energy losses occur due to external influences on the considered water body and due to the internal friction caused by the turbulent flow of water. In practice, free surface flow is often calculated by using two-dimensional depth-averaged mathematical models. The mathematical model PCFLOW2D-ORTHOCURVE was built to analyse the flow in steep curved streams. It is based on the orthogonal curvilinear numerical mesh. Before the application of the model on examples of complex geometry natural flows, its accuracy was verified in the case of flow in a semi-circular curved channel. A 20 m wide channel with a curvature radius of 30 m in the axis and the horizontal bottom of the channel was applied. There were straight channel sections of 100 m before and behind the curve, respectively. The roughness coefficient of the channel was negligibly small, thus eliminating the impact of bottom and banks on the flow and energy losses. The flow depth distribution was calculated for different average flow velocities in the curve of approximately 1 m/s to about 9 m/s The critical depth, the depth of water at the upstream and downstream boundaries of the straight section of the channel, and the mean velocity of the flow in the curved section were determined, by means of which the theoretical value of the transverse slope of free surface was calculated. This was compared with the numerically calculated value.