Application of a roughness-length representation to parameterize energy loss in 3-D numerical simulations of large rivers

• Autores: Sandbach, Steven D.; Lane, Stuart N.; Hardy, Richard J.; Amsler, Mario Luis; Ashworth, Philip J.; Best, James L.; Nicholas, Andrew P.; Orfeo, Oscar; Parsons, Daniel R.; Reesink, Arjan; Szupiany, Ricardo Nicolas
• Año de publicación: 2012
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: LARGE RIVERS; CFD; ROUGHNESS PARAMETERIZATION; SECONDARY FLOW; ENERGY LOSS; BED RESISTANCE
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Recent technological advances in remote sensing have enabled investigation of the morphodynamics and hydrodynamics of large rivers. However, measuring topography and flow in these very large rivers is time consuming and thus often constrains the spatial resolution and reach-length scales that can be monitored. Similar constraints exist for computational fluid dynamics (CFD) studies of large rivers, requiring maximization of mesh- or grid-cell dimensions and implying a reduction in the representation of bedform-roughness elements that are of the order of a model grid cell or less, even if they are represented in available topographic data. These "subgrid" elements must be parameterized, and this paper applies and considers the impact of roughness-length treatments that include the effect of bed roughness due to "unmeasured" topography. CFD predictions were found to be sensitive to the roughness-length specification. Model optimization was based on acoustic Doppler current profiler measurements and estimates of the water surface slope for a variety of roughness lengths. This proved difficult as the metrics used to assess optimal model performance diverged due to the effects of large bedforms that are not well parameterized in roughness-length treatments. However, the general spatial flow patterns are effectively predicted by the model. Changes in roughness length were shown to have a major impact upon flow routing at the channel scale. The results also indicate an absence of secondary flow circulation cells in the reached studied, and suggest simpler two-dimensional models may have great utility in the investigation of flow within large rivers
Fil: Sandbach, Steven D.. Durham University - Department Of Geography; Reino Unido
Fil: Lane, Stuart N.. Universite´ de Lausanne, Lausanne, Switzerland; Suiza
Fil: Hardy, Richard J.. Durham University - Department Of Geography; Reino Unido
Fil: Amsler, Mario Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; Argentina
Fil: Ashworth, Philip J.. University Of Brighton - School Of The Envirom And Tech; Reino Unido
Fil: Best, James L.. University Of Illinois - Dept. Of Geology And Geography; Estados Unidos
Fil: Nicholas, Andrew P.. University Of Exeter - Department Of Geography; Argentina
Fil: Orfeo, Oscar. Centro de Ecología Aplicada, Conicet; Argentina
Fil: Parsons, Daniel R.. University Of Hull, Hull, Uk; Argentina
Fil: Reesink, Arjan. University Of Brighton - School Of The Envirom And Tech; Argentina
Fil: Szupiany, Ricardo Nicolas. Universidad Nacional del Litoral. Facultad de Ingeniería y Ciencias Hídricas. Departamento de Hidráulica; Argentina