Investigação de efeitos de escoamento 3D e de ondas de vento na aplicação de um modelo de transporte de sedimentos

Abstract

Most of the sediment transport formulas is parameterized in terms of a bottom shear stress defined from vertical velocities (2DH). In the usual calculation, is assumed that the direction of sediment transport follows the vector velocity 2DH, (Meyer-Peter and Müller (1948), Engelund and Hansen (1967), Van Rijn (1984, 2007). Morphodynamic processes occur in three-dimensions, hence 3D models are more realistic to represent them. In fact, in some situations the direction of currents near to the bottom may be significantly different from the direction of the vertical currents. As the largest portion of sediment occurs by bead-load transport (near the bottom), it is important to assume a more realistic transport direction than that defined by 2DH currents. The wind waves also interfere in the solid transport, as the combined wacecurrents interaction promotes an increase of the transport capacity. This work aims to evaluate the effects of adjusting the direction of currents near the bottom via 3D models versus 2DH currents, as well as effects due to wave action in of non-cohesive sediments models. In the comparative analyzes 2DH and 3D hydrodynamic models of the SisBaHiA® (Base System of Environmental Hydrodynamics - www.sisbahia.coppe.ufrj.br) was adopted, with the coupling of wave generation and transport models sediments with morphological evolution. The analyzes indicate significant changes in sediment transport, when the effects of waves and direction of currents near the bottom are considered, compared to the usual 2DH approach.