Investigação sobre as Variações do Coeficiente de Manning em Função da Estrutura do Escoamento Uniforme em Canais

Abstract

This study investigated the variations of Manning's coefficient (n) as a function of uniform flow structure in open channels, considering the influence of flow depth and secondary currents. The central hypothesis is that Manning's coefficient should not be treated as a fixed value but rather as a variable parameter dependent on the hydraulic conditions of the flow. To investigate this, experimental data from different channel sections (triangular, circular, and rectangular) and lining materials (sand, asbestos cement, steel, concrete, among others) were analyzed, sourced from relevant literature. The results indicate that Manning's coefficient exhibits greater dispersion in shallower flows, suggesting a significant influence of local roughness and secondary currents. Furthermore, variations in n were more pronounced in channels with high aspect ratios and under turbulent flow regimes. It is concluded that the traditional approach of using fixed tabulated values for Manning's coefficient may not adequately represent the complexity of real-world flows, reinforcing the need for models that account for the variability of this parameter based on hydraulic conditions.