Transverse Velocities and Vortices in Compound Meandering Channel: Effect of Building Arrangement in the Floodplains

Numerical simulations were carried out in a compound meandering channel to investigate the effect of building arrangements in the floodplain on the flow field in the main channel. Three types of structural arrangements were used: structural obstacles parallel and perpendicular to the flow of the floodplain (MGT and MHT), and checkered structural barriers (MFT). Numerical simulation results showed that the building arrangements in the floodplain can significantly change the transverse velocities and flow angle in the main channel. Near the convex arc of the apex sections (CS1 and CS7), the transverse flow velocity increased by changing the building arrangements from parallel to the floodplain flow (MGT1) to perpendicular to the floodplain flow (MHT1) (517% increase), but in the center of the main channel in the middle section (CS4), the transverse flow velocity decreases with the change of the arrangement from the parallel state (MGT1) to the perpendicular state to the floodplain flow (MHT1) (47% decrease). In the CS4, the maximum transverse flow velocity in cases MFT1, MGT1 and MHT1 decreases by 84%, 49% and 80% on average respectively, compared to the smooth floodplain (MAT). In the center of the CS4, the change of arrangement has the greatest effect on the flow angle, so that the lowest flow angle is observed for cases with the arrangement of buildings perpendicular to the floodplain flow and checkered (MHT and MFT). Also, in the middle section, the strength of vortices rotation increases significantly in the case of MGT1 compared to the case of MHT1.