Numerical Analysis of the Ebro River Meander Flow Field, Upstream of the Bridge Pavilion

• Autor(a) principal: Santos, César Augusto Vaz
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.6/13008
• topic: Dinâmica de Fluidos Computacional; Erosão Localizada; Escoamento Secundário; Pilar Complexo; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Civil

The construction of infrastructures inside water channels has always been challenging for engineers. Concerning bridge piers, concerns about local scour and morphology changes induced by the pier are ever-present. With the recent computational advancements, numerical tools have played a fundamental role in understanding flow hydrodynamics. As such, this work resorts to the ANSYS Fluent software to analyse the Ebro River meander flow field and the effects caused by the large and complex pier of the Zaragoza Bridge Pavilion. The shape, size, and skewed position of the pier relative to the flow make the flow-structure interaction unique to this case. Initially, an inviscid model is used to provide qualitative insight into the flow field over the 5000 m long and 200 m wide domain, with a maximum water depth of 8 m. For this case, the natural bed topography is considered. Afterwards, a 1/62.5 scaled model is used for the turbulence modelling, considering a representative geometry of the meander. The RANS equations are solved using the Standard k - e turbulence model. The results are compared with previous experimental work and field surveys after the numerical validation. The results show that the core of high velocities along the bend is directed toward the outer bank. Under the right span of the bridge, a velocity increase of up to 50% is seen. On the left side, the velocity increase is less pronounced. Downstream of the pier, the wake region is detected, and the vortex pair is also present. Turbulence kinetic energy results show peak values close to the bed, under the right span of the pier. Bed shear stress results show a twofold general increase in the vicinity of the pier and a five times increase on the right side. Secondary currents are detected along the bend, with intensities up to 12% of the streamwise velocity at the 115? section. Then, the intensity starts to decrease toward the bend exit. The secondary current rapidly decays along the straight reach until a weak flux toward the inner bank replaces it.