Numerical Modeling of 2D Transient Flows with Time and Space Varying Friction Factor and Morphological Change

Ramos N.G.; Astocahuana S.I.Q. · Proceedings of the IAHR World Congress (2022) · DOI: 10.3850/iahr-39wc2521716x2022601

Resumen

Numerical modeling of 2D transient flows in coarse sediment beds is developed. The numerical experimentation was carried out in the Huatocay Sector of the Chillon River with an initial trapezoidal cross section. Topographic surveys were carried out before and at the end of the flood transit, with the extraction and laboratory analysis of 17 samples of the bed material to obtain the global granulometry. The measurement of velocity, water depth and river flow was performed with an ADCP for the medium and high flow range. A computational algorithm is developed and implemented that includes the numerical modeling of permanent flow, the elaboration of the input information, the equations of the space and time-varying friction factor, and the general scour of the channel. The time of the numerical simulation was from 1/12/2018 to 31/5/2019, with daily time interval and 0.5 m x 0.5 m cell size. The results obtained suggest that the numerical modeling allows to study the transient morphological behavior for values of the flow head less than 0.7 m; for higher values of the indicated head, the numerical modeling does not allow to study the transient morphological behavior in the mesoforms. From the analysis of results, it was found that scour intensifies for low values of friction factor, around 0.03. It is concluded that the numerical modeling allowed to capture the morphological changes, such as central and lateral bars for a range of water depth. For the vertical deformation of the channel with coarse sediment bed, acceptable results are obtained for water depths less than 1.13 m. Hydraulic characteristics were determined for the 2018 and 2019 morphological changes in the studied section of the Chillon River.

Instituciones: Universidad Nacional Agraria La Molina