Factors influencing the calculation of periodic secondary circulation in a tidal river: numerical modelling of the lower Sacramento River, USA

摘要: Secondary circulation is the component of three-dimensional (3D) flow in river channels perpendicular to primary direction. calculated from acoustic Doppler current profiler (ADCP) transects sensitive calculation method and affected by transect angle relative mean direction variations along a transect. To quantify bounds on alignment for field data collection examine tidal time-scale variability secondary circulation, 3D hydrodynamic model UnTRIM was applied simulate hydrodynamics lower reach Sacramento River (CA, USA). using Rozovskii zero net discharge methods repeated extracted results regions both relatively uniform complex flows. When depth-averaged varied more than about 5 °, occurring when as little 10 20 ° out normal direction, produced realistic method. Analysis indicated that ADCP should be within calculating circulation. strength around two tidally influenced bends generally increased with increasing broke down near slack water. However, not only function magnitude, but also depended water location curvature, which Copyright © 2015 John Wiley & Sons, Ltd.