Study of Transverse Flows and Secondary Currents in Compound Meandering Channel under the Effect of Building Arrangements

In the present study, flow characteristics in compound meandering channels under the changes of building arrangement in the floodplains were investigated using a numerical simulation. A constant sinuosity factor of ۱.۲۱ and relative flow depths (Dr) of ۰.۲۹ to ۰.۴۹ were considered to illustrate the effect of the hydraulic parameters on the variations of the velocity components. Three types of building arrangements, including structural obstacles perpendicular to the flow of the floodplain (MHT, density=۱۸.۵%), structural obstacles parallel to the flow of the floodplain (MGT, density=۲۳.۷%), and checkered structural obstacles (MFT, density=۲۳.۷%), were used. The simulated data were in good agreement with the experimental data indicating the proper ability of the numerical model in simulation. The result reveals that in the concave arc of sections CS۱ and CS۷ (apex sections), changing the building arrangements has a negligible effect on the change of transverse and secondary flows due to the parallelism of the main channel flow and the floodplain flow as well as the insignificant effect of the floodplain flow on the main channel. But near the convex arc, these changes are more significant. Hence in section CS۴, with the increase of the Dr from ۰.۲۹ to ۰.۴۹, for cases MAT, MGT, and MHT, the maximum value of depth-averaged transverse flow strength increases by ۶۱%, ۹۱%, and ۴۱%, respectively.

کلیدواژه ها:

Compound meandering channel ، Building arrangements ، Transverse flow ، Secondary cell