2019 CSCE Annual Conference - Laval (Greater Montreal)

2019 CSCE Annual Conference - Laval (Greater Montreal) Conference


Title
COMPARATIVE STUDY OF THE HEC-RAS, IBER AND FLOW 3D SOFTWARES IN STUDYING FLOW CARACTERISTICS ACROSS A DYNAMIC MEANDER IN COLOMBIA

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Author(s)
Mrs. Juliana Vargas, Universidad Nacional de Colombia (Presenter)
Mr. Leonel de Jesus Rivera Grisales, Universidad Nacional de Colombia Sede Manizales
Mr. Alejandro Salazar, Universidad Nacional de Colombia
Mrs. Valentina Robledo
Dr. Philippe Chang, Universidad Nacional de Colombia Sede Manizales
Abstract

La Dorada Township (Caldas, Colombia) is located mid-way upstream along the west bank of the Magdalena River. In this region the channel banks have been affected by severe erosion as a consequence of the flow dynamics across a series of meanders. This work presents a comparative analysis of the HEC-RAS, IBER and FLOW 3D softwares as they are implemented in the characterization process of the channel flow dynamics, assessing their capabilities and limitations. Two field campaigns were completed in the region in February and May 2018 over the dry and rainy seasons respectively and included topographical and bathymetric surveys and river bed samples collection. Modelling of the river stretch was undertaken using a digital elevation model and field data. The three hydraulic models were prepared considering equivalent 1D, 2D and 3D conditions hence comparing simulated results with field data. The study results highlighted the limitations and applicability of the latter in correctly modeling secondary currents across a curved channel and non-hydrostatic pressure conditions. Specifically the study points to: i) the validity of a 1D model if specific conditions related to channel characteristics and discretization of the domain can be met; ii) the shortcoming of the 2D shallow water equations in such case, and its inability to determine a non-zero, constant vertical velocity component across the channel depth; and iii) the requirement of a 3D model to correctly reproduce the three-dimensional velocity field distribution necessary to explain specific erosion processes occurring in meanders for example.